gnuplot-qt 4.6.4-2 / usr / share / gnuplot / gnuplot.gih

?gnuplot
?copyright
?license
     Copyright (C) 1986 - 1993, 1998, 2004, 2007  Thomas Williams, Colin Kelley

 Permission to use, copy, and distribute this software and its
 documentation for any purpose with or without fee is hereby granted,
 provided that the above copyright notice appear in all copies and
 that both that copyright notice and this permission notice appear
 in supporting documentation.

 Permission to modify the software is granted, but not the right to
 distribute the complete modified source code.  Modifications are to
 be distributed as patches to the released version.  Permission to
 distribute binaries produced by compiling modified sources is granted,
 provided you
   1. distribute the corresponding source modifications from the
    released version in the form of a patch file along with the binaries,
   2. add special version identification to distinguish your version
    in addition to the base release version number,
   3. provide your name and address as the primary contact for the
    support of your modified version, and
   4. retain our contact information in regard to use of the base
    software.
 Permission to distribute the released version of the source code along
 with corresponding source modifications in the form of a patch file is
 granted with same provisions 2 through 4 for binary distributions.

 This software is provided "as is" without express or implied warranty
 to the extent permitted by applicable law.


       AUTHORS

       Original Software:
          Thomas Williams,  Colin Kelley.

       Gnuplot 2.0 additions:
          Russell Lang, Dave Kotz, John Campbell.

       Gnuplot 3.0 additions:
          Gershon Elber and many others.

       Gnuplot 4.0 additions:
          See list of contributors at head of this document.
?introduction
?
 `Gnuplot` is a portable command-line driven graphing utility for Linux, OS/2,
 MS Windows, OSX, VMS, and many other platforms. The source code is copyrighted
 but freely distributed (i.e., you don't have to pay for it). It was originally
 created to allow scientists and students to visualize mathematical functions
 and data interactively, but has grown to support many non-interactive uses
 such as web scripting. It is also used as a plotting engine by third-party
 applications like Octave. Gnuplot has been supported and under active
 development since 1986. 

 Gnuplot supports many types of plots in either 2D and 3D. It can draw using
 lines, points, boxes, contours, vector fields, surfaces, and various
 associated text. It also supports various specialized plot types.

 Gnuplot supports many different types of output: interactive screen terminals
 (with mouse and hotkey input), direct output to pen plotters or modern
 printers, and output to many file formats (eps, emf, fig, jpeg, LaTeX, pdf, png,
 postscript, ...). Gnuplot is easily extensible to include new output modes.
 Recent additions include interactive terminals based on wxWidgets (usable
 on multiple platforms), and Qt.  Mouseable plots embedded in web pages
 can be generated using the svg or HTML5 canvas terminal drivers.

 The command language of `gnuplot` is case sensitive, i.e. commands and
 function names written in lowercase are not the same as those written in
 capitals. All command names may be abbreviated as long as the abbreviation is
 not ambiguous. Any number of commands may appear on a line, separated by
 semicolons (;). Strings may be set off by either single or double quotes,
 although there are some subtle differences.  See `syntax` and `quotes` for
 more details. Examples:

       load "filename"
       cd 'dir'

 Commands may extend over several input lines by ending each line but the last
 with a backslash (\).  The backslash must be the _last_ character on each
 line.  The effect is as if the backslash and newline were not there.  That
 is, no white space is implied, nor is a comment terminated.  Therefore,
 commenting out a continued line comments out the entire command
 (see `comments`).  But note that if an error occurs somewhere on a multi-line
 command, the parser may not be able to locate precisely where the error is
 and in that case will not necessarily point to the correct line.

 In this document, curly braces ({}) denote optional arguments and a vertical
 bar (|) separates mutually exclusive choices.  `Gnuplot` keywords or `help`
 topics are indicated by backquotes or `boldface` (where available).  Angle
 brackets (<>) are used to mark replaceable tokens.  In many cases, a default
 value of the token will be taken for optional arguments if the token is
 omitted, but these cases are not always denoted with braces around the angle
 brackets.

 For built-in help on any topic, type `help` followed by the name of the topic
 or `help ?` to get a menu of available topics.

 The new `gnuplot` user should begin by reading about `plotting` (if in an
 interactive session, type `help plotting`).

 See the simple.dem demo, also available together with other demos on the web page
           http://www.gnuplot.info/demo/
 `Gnuplot` can be started from a command line or from an icon according to the
 desktop environment. Running it from command line can take the syntax
       gnuplot {OPTIONS} file1 file2 ...
 where file1, file2, etc. are input file as in the `load` command.
 On X11-based systems, you can use
       gnuplot {X11OPTIONS} {OPTIONS} file1 file2 ...
 see your X11 documentation and `x11` in this document.

 Options interpreted by gnuplot may come anywhere on the line.  Files are
 executed in the order specified, as are commands supplied by the -e option,
 for example
       gnuplot   file1.in   -e "reset"   file2.in

 The special filename "-" is used to force reading from stdin.  `Gnuplot` exits
 after the last file is processed.  If no load files are named, `Gnuplot` takes
 interactive input from stdin.  See help `batch/interactive` for more details.
 The options specific to gnuplot can be listed by typing
       gnuplot --help
 See `command line options` for more details.

 In sessions with an interactive plot window you can hit 'h' anywhere on the
 plot for help about `hotkeys` and `mousing` features.
 Section `seeking-assistance` will help you to find further information, help
 and FAQ.
?help-desk
?seeking-assistance
?faq
?FAQ
 The canonical gnuplot web page can be found at
           http://www.gnuplot.info

 Before seeking help, please check file FAQ.pdf or the above website for
           FAQ (Frequently Asked Questions) list.

 If you need help as a gnuplot user, please use the newsgroup
           comp.graphics.apps.gnuplot
 We prefer that you read the messages through the newsgroup rather than
 subscribing to the mailing list which is also available and carries the same
 set of messages. Instructions for subscribing to gnuplot mailing lists may be
 found via the gnuplot development website on SourceForge
           http://sourceforge.net/projects/gnuplot

 The address for mailing to list members is:
           gnuplot-info@lists.sourceforge.net

 Bug reports and code contributions should be uploaded to the trackers at
           http://sourceforge.net/projects/gnuplot/support
 Please check previous bug reports if the bug you want to report has not been
 already fixed in a newer version of gnuplot.

 A mailing list for those interested in development version of gnuplot is:
           gnuplot-beta@lists.sourceforge.net

 When posting a question, please include full details of the gnuplot version,
 the terminal type, and the operating system you are using.  A _small_ script
 demonstrating the problem may be useful.  Function plots are preferable to
 datafile plots.

?new-features
 This section lists major additions since version 4.4.
 For a more exhaustive list, see the NEWS file.

 This version of gnuplot introduces command iteration and block-structured
 if/else/while/do constructs.  See `if`, `while`, and `do`.
 Simple iteration is possible inside `plot` or `set` commands.
 See `iteration`.  General iteration spanning multiple
 commands is possible using a block construct as shown below.
 For a related new feature, see the `summation` expression type.
 Here is an example using several of these new syntax features:
       set multiplot layout 2,2
       fourier(k, x) = sin(3./2*k)/k * 2./3*cos(k*x)
       do for [power = 0:3] {
           TERMS = 10**power
           set title sprintf("%g term Fourier series",TERMS)
           plot 0.5 + sum [k=1:TERMS] fourier(k,x) notitle 
       }
       unset multiplot
 
 It is now possible to select a column of data from a data file by
 matching a label in the first row of the file. See `columnhead`.
 For example
       plot for [crop in "Oats Peas Beans"] 'data' using "Year":crop

 You can now customize properties (color, linewidth, point type) of the
 default sequence of linetypes used in plotting. See `set linetype`.
 This is normally done in an initialization file, either the system-wide
 file `gnuplotrc` or a private file `~/.gnuplot`. See `initialization`.

 Most terminals now allow you to set an explicit background color for the plot.
 The special linetype `bgnd` can be used to draw in this color. See `bgnd`.

 See documentation for plot styles `boxplot`, `circles`, `ellipses`, and
 `fillsteps`.

 Polar plot mode has been reworked to support additional plot styles.
 The polar axes can now be drawn and labeled independent of the x and y
 axes. See `set polar` and `set rrange`.

 New smoothing algorithms have been added for both 2- and 3-dimensional plots.
 `smooth kdensity` and `smooth cumulative` can be used with `plot` to draw 
 smooth histograms and cumulative distribution functions.  Several new smoothing
 kernels have been added to `dgrid3d` for use with `splot`.
 See `smooth` `dgrid3d`.

 Gnuplot now tracks time to millisecond precision. Time formats have been
 modified to match this. The new built-in function time() returns the current
 time of day according to the system clock.
 Example: print the current time to msec precision
      print strftime("%H:%M:%.3S %d-%b-%Y",time(0.0))
      18:15:04.253 16-Apr-2011
 The new `stats` command reads data from a file using the same syntax as
 the `plot` or `splot` commands. Rather than drawing a graph, it prints
 out a statistical summary of the data contained in the column[s] requested.
 The resulting statistics  min, max, mean, standard deviation, correlation,
 etc. are also stored in named variables that can be used to compose or modify
 subsequent plotting commands.  See `stats`.

 The `qt` driver implements an interactive terminal on top of the Qt
 graphics layer.  It can function either as a window in a full-featured
 desktop enviroment or as a full-screen application on a Qt-based 
 embedded device.  The `qt` terminal is new and may still have some
 rough edges.

 Two terminal types support web-based interactive display. The HTML5 `canvas`
 terminal was introduced in version 4.4. The `svg` terminal has been extensively
 revised to include support for mousing and better incorporation of svg plots
 from gnuplot into larger svg/xml documents.

 The `canvas` terminal driver produces javascript output that draws onto the
 HTML canvas element of a web page.  It can produce either a complete web page
 containing a single plot, or a script that can be embedded as part of an
 externally generated HTML document that perhaps contains multiple plots.
 The embedded plots support browser-side mousing, including zoom/unzoom.

 The `lua` terminal driver creates data intended to be further processed
 by a script in the lua programming language.  At this point only one such
 lua script, gnuplot-tikz.lua, is available.  It produces a TeX document
 suitable for use with the latex TikZ package.  Other lua scripts could be
 written to process the gnuplot output for use with other TeX packages,
 or with other non-TeX tools.

 `set term tikz` is shorthand for `set term lua tikz`.  As decribed above, it
 uses the generic lua terminal and an external lua script to produce a latex
 document.

 The `context` terminal driver creates output to be further processed by
 the ConTeXt TeX macro package. To process its output, you additionally require
 the gnuplot module for ConTeXt available at
           http://ctan.org/pkg/context-gnuplot

 The `epscairo` terminal uses the cairo and pango libraries to create
 encapsulated postscript (eps) ouput. It is an alternative to the `postscript`
 terminal driver for those who would like to have their eps files look equal
 to e.g. screen output by the `wxt` terminal.

 The `cairolatex` terminal uses the cairo backend of the `pdfcairo` or 
 `epscairo` terminal to produce graphs for inclusion in LaTeX documents. It
 creates pdf or eps graphics but transfers texts to LaTeX in the same way as
 the `epslatex` terminal.
 
 The `windows` terminal driver has been revised to suport transparency,
 antialiasing, buffered output, multiple graph windows and copying to clipboard
 and saving of graphs as emf files. It has many new options and a revised user
 interface. Additionaly, the code of the text console has been largely rewritten
 to support wrapping of long lines. Help is now provided via HTML.

?backwards compatibility
?compatibility
 Gnuplot version 4.0 deprecated certain syntax used in earlier versions, but
 continued to recognize it.  This is now under the control of a configuration
 option, and can be enabled as follows:

       ./configure --enable-backwards-compatibility

 Notice: Deprecated syntax items may be removed entirely in some future
 version of gnuplot.

 One major difference is the introduction of keywords to disambiguate complex
 commands, particularly commands containing string variables. A notable issue
 was the use of bare numbers to specify offsets, line and point types.
 Illustrative examples:

 Deprecated:
       set title "Old" 0,-1
       set data linespoints
       plot 1 2 4               # horizontal line at y=1
 New:
       TITLE = "New"
       set title TITLE offset char 0, char -1
       set style data linespoints
       plot 1 linetype 2 pointtype 4

?batch/interactive
?command line options
 `Gnuplot` may be executed in either batch or interactive modes, and the two
 may even be mixed together on many systems.

 Any command-line arguments are assumed to be either program options (first
 character is -) or names of files containing `gnuplot` commands. The option
 -e "command" may be used to force execution of a gnuplot command. Each file
 or command string will be executed in the order specified.  The special
 filename "-" is indicates that commands are to be read from stdin.
 `Gnuplot` exits after the last file is processed.  If no load files and no 
 command strings are specified, `gnuplot` accepts interactive input from
 stdin.

 Both the `exit` and `quit` commands terminate the current command file and
 `load` the next one, until all have been processed.

 Examples:

 To launch an interactive session:
       gnuplot

 To launch a batch session using two command files "input1" and "input2":
       gnuplot input1 input2

 To launch an interactive session after an initialization file "header" and
 followed by another command file "trailer":
       gnuplot header - trailer

 To give `gnuplot` commands directly in the command line, using the "-persist"
 option so that the plot remains on the screen afterwards:
       gnuplot -persist -e "set title 'Sine curve'; plot sin(x)"

 To set user-defined variables a and s prior to executing commands from a file:
       gnuplot -e "a=2; s='file.png'" input.gpl

?canvas size
?canvas
?set term size

 In earlier versions of gnuplot, some terminal types used the values from
 `set size` to control also the size of the output canvas; others did not.
 The use of 'set size' for this purpose was deprecated in version 4.2.
 Since version 4.4 almost all terminals now behave as follows:

 `set term <terminal_type> size <XX>, <YY>` controls the size of the output
 file, or "canvas". Please see individual terminal documentation for allowed
 values of the size parameters.  By default, the plot will fill this canvas.

 `set size <XX>, <YY>` scales the plot itself relative to the size of the
 canvas.  Scale values less than 1 will cause the plot to not fill the entire
 canvas.  Scale values larger than 1 will cause only a portion of the plot to
 fit on the canvas.  Please be aware that setting scale values larger than 1
 may cause problems on some terminal types.

 The major exception to this convention is the PostScript driver, which
 by default continues to act as it has in earlier versions. Be warned that
 the next version of gnuplot may change the default behaviour of the
 PostScript driver as well.

 Example:

       set size 0.5, 0.5
       set term png size 600, 400
       set output "figure.png"
       plot "data" with lines

 These commands will produce an output file "figure.png" that is 600 pixels
 wide and 400 pixels tall. The plot will fill the lower left quarter of this
 canvas.  This is consistent with the way multiplot mode has always worked.

?line-editing
?editing
?command-line-editing
 Command-line editing and command history are supported using either an
 external gnu readline library, an external BSD libedit library,  or a
 built-in equivalent.  This choice is a configuration option at the time
 gnuplot is built.

 The editing commands of the built-in version are given below. Please note that
 the action of the DEL key is system-dependent. The gnu readline and BSD libedit
 libraries have their own documentation.

       `Line-editing`:

       ^B    moves back a single character.
       ^F    moves forward a single character.
       ^A    moves to the beginning of the line.
       ^E    moves to the end of the line.
       ^H    deletes the previous character.
       DEL   deletes the current character.
       ^D    deletes current character, sends EOF if the line is empty.
       ^K    deletes from current position to the end of line.
       ^L,^R redraws line in case it gets trashed.
       ^U    deletes the entire line.
       ^W    deletes previous word.

       `History`:

       ^P    moves back through history.
       ^N    moves forward through history.

?comments
 Comments are supported as follows: a `#` may appear in most places in a line
 and `gnuplot` will ignore the rest of the line.  It will not have this effect
 inside quotes, inside numbers (including complex numbers), inside command
 substitutions, etc.  In short, it works anywhere it makes sense to work.

 See also `set datafile commentschars` for specifying comment characters in
 data files.  Note that if a comment line ends in '\' then the subsequent
 line is also treated as a comment.
?coordinates
 The commands `set arrow`, `set key`, `set label` and `set object` allow you
 to draw something at an arbitrary position on the graph.  This position is
 specified by the syntax:

       {<system>} <x>, {<system>} <y> {,{<system>} <z>}

 Each <system> can either be `first`, `second`, `graph`, `screen`, or
 `character`.

 `first` places the x, y, or z coordinate in the system defined by the left
 and bottom axes; `second` places it in the system defined by the second axes
 (top and right); `graph` specifies the area within the axes---0,0 is bottom
 left and 1,1 is top right (for splot, 0,0,0 is bottom left of plotting area;
 use negative z to get to the base---see `set xyplane`); `screen`
 specifies the screen area (the entire area---not just the portion selected by
 `set size`), with 0,0 at bottom left and 1,1 at top right; and `character`
 gives the position in character widths and heights from the bottom left of
 the screen area (screen 0,0), `character` coordinates depend on the chosen
 font size.

 If the coordinate system for x is not specified, `first` is used.  If the
 system for y is not specified, the one used for x is adopted.

 In some cases, the given coordinate is not an absolute position but a
 relative value (e.g., the second position in `set arrow` ... `rto`).  In
 most cases, the given value serves as difference to the first position.
 If the given coordinate resides in a logarithmic axis the value is
 interpreted as factor. For example,

       set logscale x
       set arrow 100,5 rto 10,2

 plots an arrow from position 100,5 to position 1000,7 since the x axis is
 logarithmic while the y axis is linear.

 If one (or more) axis is timeseries, the appropriate coordinate should
 be given as a quoted time string according to the `timefmt` format string.
 See `set xdata` and `set timefmt`.  `Gnuplot` will also accept an integer
 expression, which will be interpreted as seconds from 1 January 2000.
?datastrings
 Data files may contain string data consisting of either an arbitrary string
 of printable characters containing no whitespace or an arbitrary string of
 characters, possibly including whitespace, delimited by double quotes.
 The following sample line from a datafile is interpreted to contain four
 columns, with a text field in column 3:

   1.000 2.000 "Third column is all of this text" 4.00

 Text fields can be positioned within a 2-D or 3-D plot using the commands:

   plot 'datafile' using 1:2:4 with labels
   splot 'datafile' using 1:2:3:4 with labels

 A column of text data can also be used to label the ticmarks along one or more
 of the plot axes. The example below plots a line through a series of points
 with (X,Y) coordinates taken from columns 3 and 4 of the input datafile.
 However, rather than generating regularly spaced tics along the x axis
 labeled numerically, gnuplot will position a tic mark along the x axis at the
 X coordinate of each point and label the tic mark with text taken from column
 1 of the input datafile.

   set xtics
   plot 'datafile' using 3:4:xticlabels(1) with linespoints

 There is also an option that will interpret the first entry in a column of
 input data (i.e. the column heading) as a text field, and use it as the key
 title for data plotted from that column. The example given below will use the
 first entry in column 2 to generate a title in the key box, while processing
 the remainder of columns 2 and 4 to draw the required line:

   plot 'datafile' using 1:(f($2)/$4) with lines title columnhead(2)

 Another example:

   plot for [i=2:6] 'datafile' using i title "Results for ".columnhead(i)

 See `set style labels`, `using xticlabels`, `plot title`, `using`.
?enhanced text
?enhanced
 Many terminal types support an enhanced text mode in which additional
 formatting information is embedded in the text string.  For example, "x^2"
 will write x-squared as we are used to seeing it, with a superscript 2.
 This mode is normally selected when you set the terminal, e.g.
 "set term png enhanced", but may also be toggled afterward using
 "set termoption enhanced", or by marking individual strings as in
 "set label 'x_2' noenhanced".

  Control      Examples        Explanation
   ^           a^x             superscript
   _           a_x             subscript
   @           @x or a@^b_{cd} phantom box (occupies no width)
   &           &{space}        inserts space of specified length
   ~           ~a{.8-}         overprints '-' on 'a', raised by .8
                               times the current fontsize


 Braces can be used to place multiple-character text where a single character
 is expected (e.g., 2^{10}).  To change the font and/or size, use the full form:
 {/[fontname][=fontsize | *fontscale] text}.  Thus {/Symbol=20 G} is a 20 pt
 GAMMA and {/*0.75 K} is a K at three-quarters of whatever fontsize is currently
 in effect.  (The '/' character MUST be the first character after the '{'.)

 The phantom box is useful for a@^b_c to align superscripts and subscripts
 but does not work well for overwriting an accent on a letter.  For the latter,
 it is much better to use an encoding  (e.g. iso_8859_1 or utf8) that contains
 a large variety of letters with accents or other diacritical marks.  See
 `set encoding`. Since the box is non-spacing, it is sensible to put the shorter
 of the subscript or superscript in the box (that is, after the @).

 Space equal in length to a string can be inserted using the '&' character.
 Thus
         'abc&{def}ghi'
 would produce
         'abc   ghi'.

 The '~' character causes the next character or bracketed text to be
 overprinted by the following character or bracketed text.  The second text
 will be horizontally centered on the first.  Thus '~a/' will result in an 'a'
 with a slash through it.  You can also shift the second text vertically by
 preceding the second text with a number, which will define the fraction of the
 current fontsize by which the text will be raised or lowered.  In this case
 the number and text must be enclosed in brackets because more than one
 character is necessary.  If the overprinted text begins with a number, put a
 space between the vertical offset and the text ('~{abc}{.5 000}'); otherwise
 no space is needed ('~{abc}{.5---}').  You can change the font for one or
 both strings ('~a{.5 /*.2 o}'---an 'a' with a one-fifth-size 'o' on top---and
 the space between the number and the slash is necessary), but you can't
 change it after the beginning of the string.  Neither can you use any other
 special syntax within either string.  You can, of course, use control
 characters by escaping them (see below), such as '~a{\^}'

 You can access special symbols numerically by specifying \character-code (in
 octal), e.g., {/Symbol \245} is the symbol for infinity. This does not work
 for multibyte encodings like UTF-8, however.  In a UTF-8 environment, you
 should be able to enter multibyte sequences implicitly by typing or otherwise
 selecting the character you want.

 You can escape control characters using \, e.g.,  \\, \{, and so on.

 But be aware that strings in double-quotes are parsed differently than those
 enclosed in single-quotes.  The major difference is that backslashes may need
 to be doubled when in double-quoted strings.

 Examples (these are hard to describe in words---try them!):
       set xlabel 'Time (10^6 {/Symbol m}s)'
       set title '{/Symbol=18 \\362@_{/=9.6 0}^{/=12 x}} \\
                  {/Helvetica e^{-{/Symbol m}^2/2} d}{/Symbol m}'

 The file "ps_guide.ps" in the /docs/psdoc subdirectory of the gnuplot source
 distribution contains more examples of the enhanced syntax.
?environment
 A number of shell environment variables are understood by `gnuplot`.  None of
 these are required, but may be useful.

 If GNUTERM is defined, it is used as the name of the terminal type to be
 used.  This overrides any terminal type sensed by `gnuplot` on start-up, but
 is itself overridden by the .gnuplot (or equivalent) start-up file
 (see `startup`) and, of course, by later explicit changes.

 GNUHELP may be defined to be the pathname of the HELP file (gnuplot.gih).

 On VMS, the logical name GNUPLOT$HELP should be defined as the name of the
 help library for `gnuplot`.  The `gnuplot` help can be put inside any system
 help library, allowing access to help from both within and outside `gnuplot`
 if desired.

 On Unix, HOME is used as the name of a directory to search for a .gnuplot
 file if none is found in the current directory.  On MS-DOS, Windows and OS/2,
 GNUPLOT is used.  On Windows, the NT-specific variable USERPROFILE is also
 tried. VMS, SYS$LOGIN: is used. Type `help startup`.

 On Unix, PAGER is used as an output filter for help messages.

 On Unix, SHELL is used for the `shell` command.  On MS-DOS and OS/2, COMSPEC
 is used for the `shell` command.

 FIT_SCRIPT may be used to specify a `gnuplot` command to be executed when a
 fit is interrupted---see `fit`.  FIT_LOG specifies the default filename of the
 logfile maintained by fit.

 GNUPLOT_LIB may be used to define additional search directories for data
 and command files. The variable may contain a single directory name, or
 a list of directories separated by a platform-specific path separator,
 eg. ':' on Unix, or ';' on DOS/Windows/OS/2 platforms. The contents
 of GNUPLOT_LIB are appended to the `loadpath` variable, but not saved
 with the `save` and `save set` commands.

 Several gnuplot terminal drivers access TrueType fonts via the gd library.
 For these drivers the font search path is controlled by the environmental
 variable GDFONTPATH.  Furthermore, a default font for these drivers may be
 set via the environmental variable GNUPLOT_DEFAULT_GDFONT.

 The postscript terminal uses its own font search path. It is controlled by
 the environmental variable GNUPLOT_FONTPATH. The format is the same as for
 GNUPLOT_LIB. The contents of GNUPLOT_FONTPATH are appended to the `fontpath`
 variable, but not saved with the `save` and `save set` commands.

 GNUPLOT_PS_DIR is used by the postscript driver to search for external
 prologue files. Depending on the build process, gnuplot contains either a
 built-in copy of those files or a default hardcoded path. You can use this
 variable have the postscript terminal use custom prologue files rather than
 the default files. See `postscript prologue`.
?expressions
 In general, any mathematical expression accepted by C, FORTRAN, Pascal, or
 BASIC is valid.  The precedence of these operators is determined by the
 specifications of the C programming language.  White space (spaces and tabs)
 is ignored inside expressions.

 Complex constants are expressed as {<real>,<imag>}, where <real> and <imag>
 must be numerical constants.  For example, {3,2} represents 3 + 2i; {0,1}
 represents 'i' itself.  The curly braces are explicitly required here.

 Note that gnuplot uses both "real" and "integer" arithmetic, like FORTRAN and
 C.  Integers are entered as "1", "-10", etc; reals as "1.0", "-10.0", "1e1",
 3.5e-1, etc.  The most important difference between the two forms is in
 division: division of integers truncates: 5/2 = 2; division of reals does
 not: 5.0/2.0 = 2.5.  In mixed expressions, integers are "promoted" to reals
 before evaluation: 5/2e0 = 2.5.  The result of division of a negative integer
 by a positive one may vary among compilers.  Try a test like "print -5/2" to
 determine if your system chooses -2 or -3 as the answer.

 The integer expression "1/0" may be used to generate an "undefined" flag,
 which causes a point to ignored.  Or you can use the pre-defined variable NaN
 to achieve the same result.  See `using` for an example.

 The real and imaginary parts of complex expressions are always real, whatever
 the form in which they are entered: in {3,2} the "3" and "2" are reals, not
 integers.

 Gnuplot can also perform simple operations on strings and string variables.
 For example, the expression ("A" . "B" eq "AB") evaluates as true, illustrating
 the string concatenation operator and the string equality operator.

 A string which contains a numerical value is promoted to the corresponding
 integer or real value if used in a numerical expression. Thus ("3" + "4" == 7)
 and (6.78 == "6.78") both evaluate to true.  An integer, but not a real or
 complex value, is promoted to a string if used in string concatenation.
 A typical case is the use of integers to construct file names or other strings;
 e.g. ("file" . 4 eq "file4") is true.

 Substrings can be specified using a postfixed range descriptor [beg:end].
 For example, "ABCDEF"[3:4] == "CD"   and   "ABCDEF"[4:*] == "DEF"
 The syntax "string"[beg:end] is exactly equivalent to calling the built-in
 string-valued function substr("string",beg,end), except that you cannot
 omit either beg or end from the function call.
?expressions functions
 The math functions in `gnuplot` are the same as the corresponding functions in
 the Unix math library, except that all functions accept integer, real, and
 complex arguments unless otherwise noted.
 Functions that accept or return angles (e.g. sin(x), cos(x), arg(z))
 treat angle values as radians, but this may be changed to degrees using the
 command `set angles`.






?expressions functions abs
?abs
 The `abs(x)` function returns the absolute value of its argument.  The
 returned value is of the same type as the argument.

 For complex arguments, abs(x) is defined as the length of x in the complex
 plane [i.e.,  sqrt(real(x)**2 + imag(x)**2) ].
?expressions functions acos
?acos
 The `acos(x)` function returns the arc cosine (inverse cosine) of its
 argument.  `acos` returns its argument in radians or degrees, as selected by
 `set angles`.
?expressions functions acosh
?acosh
 The `acosh(x)` function returns the inverse hyperbolic cosine of its argument
 in radians.
?expressions functions airy
?airy
 The `airy(x)` function returns the value of the Airy function Ai(x) of its 
 argument. The function Ai(x) is that solution of the equation y'' - x y = 0
 which is everywhere finite. If the argument is complex, its imaginary part
 is ignored.
?expressions functions arg
?arg
 The `arg(x)` function returns the phase of a complex number in radians or
 degrees, as selected by `set angles`.
?expressions functions asin
?asin
 The `asin(x)` function returns the arc sin (inverse sin) of its argument.
 `asin` returns its argument in radians or degrees, as selected by `set
 angles`.
?expressions functions asinh
?asinh
 The `asinh(x)` function returns the inverse hyperbolic sin of its argument in
 radians.
?expressions functions atan
?atan
 The `atan(x)` function returns the arc tangent (inverse tangent) of its
 argument.  `atan` returns its argument in radians or degrees, as selected by
 `set angles`.
?expressions functions atan2
?atan2
 The `atan2(y,x)` function returns the arc tangent (inverse tangent) of the
 ratio of the real parts of its arguments.  `atan2` returns its argument in
 radians or degrees, as selected by `set angles`, in the correct quadrant.
?expressions functions atanh
?atanh
 The `atanh(x)` function returns the inverse hyperbolic tangent of its
 argument in radians.
 See `elliptic integrals`.
 See `elliptic integrals`.
 See `elliptic integrals`.
?expressions functions besj0
?besj0
 The `besj0(x)` function returns the j0th Bessel function of its argument.
 `besj0` expects its argument to be in radians.
?expressions functions besj1
?besj1
 The `besj1(x)` function returns the j1st Bessel function of its argument.
 `besj1` expects its argument to be in radians.
?expressions functions besy0
?besy0
 The `besy0(x)` function returns the y0th Bessel function of its argument.
 `besy0` expects its argument to be in radians.
?expressions functions besy1
?besy1
 The `besy1(x)` function returns the y1st Bessel function of its argument.
 `besy1` expects its argument to be in radians.
?expressions functions ceil
?ceil
 The `ceil(x)` function returns the smallest integer that is not less than its
 argument.  For complex numbers, `ceil` returns the smallest integer not less
 than the real part of its argument.
?expressions functions cos
?cos
 The `cos(x)` function returns the cosine of its argument.  `cos` accepts its
 argument in radians or degrees, as selected by `set angles`.
?expressions functions cosh
?cosh
 The `cosh(x)` function returns the hyperbolic cosine of its argument.  `cosh`
 expects its argument to be in radians.
?expressions functions erf
?erf
 The `erf(x)` function returns the error function of the real part of its
 argument.  If the argument is a complex value, the imaginary component is
 ignored.  See `erfc`, `inverf`, and `norm`.
?expressions functions erfc
?erfc
 The `erfc(x)` function returns 1.0 - the error function of the real part of
 its argument.  If the argument is a complex value, the imaginary component is
 ignored.  See `erf`, `inverf`, and `norm`.
?expressions functions exp
?exp
 The `exp(x)` function returns the exponential function of its argument (`e`
 raised to the power of its argument).  On some implementations (notably
 suns), exp(-x) returns undefined for very large x.  A user-defined function
 like safe(x) = x<-100 ? 0 : exp(x) might prove useful in these cases.
?expressions functions expint
?expint
 The `expint(n,x)` function returns the exponential integral of the real
 part of its argument: integral from 1 to infinity of t^(-n) e^(-tx) dt.
 n must be a nonnegative integer, x>=0, and either x>0 or n>1.
?expressions functions floor
?floor
 The `floor(x)` function returns the largest integer not greater than its
 argument.  For complex numbers, `floor` returns the largest integer not
 greater than the real part of its argument.
?expressions functions gamma
?gamma
 The `gamma(x)` function returns the gamma function of the real part of its
 argument.  For integer n, gamma(n+1) = n!.  If the argument is a complex
 value, the imaginary component is ignored.
?expressions functions ibeta
?ibeta
 The `ibeta(p,q,x)` function returns the incomplete beta function of the real
 parts of its arguments. p, q > 0 and x in [0:1].  If the arguments are
 complex, the imaginary components are ignored.  The function is approximated by
 the method of continued fractions (Abramowitz and Stegun, 1964).
 The approximation is only accurate in the region x < (p-1)/(p+q-2). 
?expressions functions inverf
?inverf
 The `inverf(x)` function returns the inverse error function of the real part
 of its argument.   See `erf` and `invnorm`.
?expressions functions igamma
?igamma
 The `igamma(a,x)` function returns the normalized incomplete gamma
 function of the real parts of its arguments, where a > 0 and x >= 0.
 The standard notation is P(a,x), e.g. Abramowitz and Stegun (6.5.1),
 with limiting value of 1 as x approaches infinity.  If the arguments
 are complex, the imaginary components are ignored.
?expressions functions imag
?imag
 The `imag(x)` function returns the imaginary part of its argument as a real
 number.
?expressions functions invnorm
?invnorm
 The `invnorm(x)` function returns the inverse cumulative normal (Gaussian)
 distribution function of the real part of its argument.  See `norm`.
?expressions functions int
?int
 The `int(x)` function returns the integer part of its argument, truncated
 toward zero.
?expressions functions lambertw
?lambertw
 The lambertw function returns the value of the principal branch of
 Lambert's W function, which is defined by the equation (W(z)*exp(W(z))=z.
 z must be a real number with z >= -exp(-1).
?expressions functions lgamma
?lgamma
 The `lgamma(x)` function returns the natural logarithm of the gamma function
 of the real part of its argument.  If the argument is a complex value, the
 imaginary component is ignored.
?expressions functions log
?log
 The `log(x)` function returns the natural logarithm (base `e`) of its
 argument.  See `log10`.
?expressions functions log10
?log10
 The `log10(x)` function returns the logarithm (base 10) of its argument.
?expressions functions norm
?norm
 The `norm(x)` function returns the cumulative normal (Gaussian) distribution
 function of the real part of its argument.   See `invnorm`, `erf` and `erfc`.
?expressions functions rand
?rand
 `rand(0)` returns a pseudo random number in the interval [0:1].
 See `random` for more details.
?expressions functions real
?real
 The `real(x)` function returns the real part of its argument.
?expressions functions sgn
?sgn
 The `sgn(x)` function returns 1 if its argument is positive, -1 if its
 argument is negative, and 0 if its argument is 0.  If the argument is a
 complex value, the imaginary component is ignored.
?expressions functions sin
?sin
 The `sin(x)` function returns the sine of its argument.  `sin` expects its
 argument to be in radians or degrees, as selected by `set angles`.
?expressions functions sinh
?sinh
 The `sinh(x)` function returns the hyperbolic sine of its argument.  `sinh`
 expects its argument to be in radians.
?expressions functions sqrt
?sqrt
 The `sqrt(x)` function returns the square root of its argument.
?expressions functions tan
?tan
 The `tan(x)` function returns the tangent of its argument.  `tan` expects
 its argument to be in radians or degrees, as selected by `set angles`.
?expressions functions tanh
?tanh
 The `tanh(x)` function returns the hyperbolic tangent of its argument.  `tanh`
 expects its argument to be in radians.
?expressions functions voigt
?voigt
 The function `voigt(x,y)` returns an approximation to the Voigt/Faddeeva
 function used in spectral analysis. The approximation is accurate to 
 one part in 10^4.

?expressions functions gprintf
 `gprintf("format",x)` applies gnuplot's own format specifiers to the single
 variable x and returns the resulting string. If you want standard C-language
 format specifiers, you must instead use `sprintf("format",x)`.
 See `format specifiers`.
?expressions functions sprintf
?sprintf
 `sprintf("format",var1,var2,...)` applies standard C-language format specifiers
 to multiple arguments and returns the resulting string. If you want to
 use gnuplot's own format specifiers, you must instead call `gprintf()`.
 For information on sprintf format specifiers, please see standard C-language
 documentation or the unix sprintf man page.
?expressions functions strlen
?strlen
 `strlen("string")` returns the length of the string in bytes.  If the current 
 encoding supports multibyte characters, this may be larger than the number of
 characters in the string.
?expressions functions strstrt
?strstrt
 `strstrt("string","key")` searches for the character string "key" in "string"
 and returns the index to the first character of "key". If "key" is not found,
 returns 0. Similar to C library function strstr except that it returns an
 index rather than a string pointer. strstrt("hayneedlestack","needle") = 4.
?expressions functions substr
?substr
 `substr("string",beg,end)` returns the substring consisting of characters
 beg through end of the original string. This is exactly equivalent to the
 expression "string"[beg:end] except that you do not have the option of
 omitting beg or end.
?expressions functions strftime
?strftime
 `strftime("timeformat",t)` applies the timeformat specifiers to the time t
 given in seconds since the year 2000.
 See `time_specifiers` and `strptime`.
?expressions functions strptime
?strptime
 `strptime("timeformat",s)` reads the time from the string s using the
 timeformat specifiers and converts it into seconds since the year 2000.
 See `time_specifiers` and `strftime`.
?expressions functions system
 `system("command")` executes "command" using the standard shell and returns
 the resulting character stream from stdout as string variable.
 One optional trailing newline is ignored.

 This can be used to import external functions into gnuplot scripts using
 'f(x) = real(system(sprintf("somecommand %f", x)))'.
?expressions functions word
?word
 `word("string",n)` returns the nth word in string. For example,
 `word("one two three",2)` returns the string "two".
?expressions functions words
?words
 `words("string")` returns the number of words in string. For example,
 `words(" a b c d")` returns 4.

?expressions functions column
?column
 `column(x)` may be used only in expressions as part of `using` manipulations
 to fits or datafile plots.  It evaluates to the numerical value of the contents
 of column x. See `plot datafile using`.
?expressions functions columnhead
?columnhead
 `columnhead(x)` may only be used in expressions as part of `using` manipulations
 to fits or datafile plots.  It evaluates to a string containing the contents of
 column x in the first line of data. See `plot datafile using`.
?expressions functions defined
?defined
 `defined(X)` [DEPRECATED] returns 1 if a variable named X has been defined, otherwise
 it returns 0.  Please use `exists("X")` instead.
?expressions functions exists
?exists
 The argument to exists() is a string constant or a string variable;
 if the string contains the name of a defined variable, the function returns 1.
 Otherwise the function returns 0.
?expressions functions stringcolumn
?stringcolumn
?expressions functions strcol
?strcol
 `stringcolumn(x)` may be used only in expressions as part of `using` manipulations
 to fits or datafile plots.  It returns the content of column x as a string variable.
 See `plot datafile using`.
?expressions functions timecolumn
?timecolumn
 `timecolumn(x)` may be used only in expressions as part of `using`
 manipulations to fits or datafile plots.   See `plot datafile using`.

 It reads the data starting at that column as a time/date value and
 returns its value in gnuplot's internal time representation of
 "seconds since the millennium".

 To find the right `timefmt` string to use, `timecolumn` searches for a
 `using` specification with the same column number as its argument.
 If one is found, `timefmt` pattern of the target axis for this specifier
 is used.  Otherwise, `timecolumn` chooses the x axis `timefmt` per default.
?expressions tm_hour
?tm_hour
 The `tm_hour` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the hour (an integer in the range 0--23) as a real.
?expressions tm_mday
?tm_mday
 The `tm_mday` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the day of the month (an integer in the range 1--31)
 as a real.
?expressions tm_min
?tm_min
 The `tm_min` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the minute (an integer in the range 0--59) as a real.
?expressions tm_mon
?tm_mon
 The `tm_mon` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the month (an integer in the range 0--11) as a real.
?expressions tm_sec
?tm_sec
 The `tm_sec` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the second (an integer in the range 0--59) as a real.
?expressions tm_wday
?tm_wday
 The `tm_wday` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the day of the week (an integer in the range 0--6) as
 a real.
?expressions tm_yday
?tm_yday
 The `tm_yday` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the day of the year (an integer in the range 1--366)
 as a real.
?expressions tm_year
?tm_year
 The `tm_year` function interprets its argument as a time, in seconds from
 1 Jan 2000.  It returns the year (an integer) as a real.
?expressions time
?time
 The `time` function returns the current system time. This value can be 
 converted to a date string with the `strftime` function, or it can be used
 in conjunction with `timecolumn` to generate relative time/date plots. 
 The type of the argument determines what is returned. If the argument is an
 integer, time() returns the current time as an integer, in seconds from 
 1 Jan 2000. If the argument is real (or complex), the result is real as well.
 If the argument is a string, it is assumed to be a format string, 
 and it is passed to `strftime` to provide a formatted time string.
?expressions functions valid
?valid
 `valid(x)` may be used only in expressions as part of `using` manipulations
 to fits or datafile plots.  See `plot datafile using`.


?expressions functions elliptic integrals
?elliptic integrals
 The `EllipticK(k)` function returns the complete elliptic integral of the first
 kind, i.e. the definite integral between 0 and pi/2 of the function
 `(1-(k*sin(p))**2)**(-0.5)`.  The domain of `k` is -1 to 1 (exclusive).

 The `EllipticE(k)` function returns the complete elliptic integral of the
 second kind, i.e. the definite integral between 0 and pi/2 of the function
 `(1-(k*sin(p))**2)**0.5`.  The domain of `k` is -1 to 1 (inclusive).

 The `EllipticPi(n,k)` function returns the complete elliptic integral of the
 third kind, i.e. the definite integral between 0 and pi/2 of the function 
 `(1-(k*sin(p))**2)**(-0.5)/(1-n*sin(p)**2)`.  The parameter `n` must be less
 than 1, while `k` must lie between -1 and 1 (exclusive).  Note that by
 definition EllipticPi(0,k) == EllipticK(k) for all possible values of `k`.
?expressions random
?random
 The function `rand()` produces a sequence of pseudo-random numbers between
 0 and 1 using an algorithm from P. L'Ecuyer and S. Cote, "Implementing a
 random number package with splitting facilities", ACM Transactions on
 Mathematical Software, 17:98-111 (1991).

       rand(0)     returns a pseudo random number in the interval [0:1]
                   generated from the current value of two internal
                   32-bit seeds.
       rand(-1)    resets both seeds to a standard value.
       rand(x)     for integer 0 < x < 2^31-1 sets both internal seeds
                   to x.
       rand({x,y}) for integer 0 < x,y < 2^31-1 sets seed1 to x and 
                   seed2 to y.
?expressions functions value
?value
 B = value("A") is effectively the same as B = A, where A is the name of a 
 user-defined variable.  This is useful when the name of the variable is itself
 held in a string variable. See `user-defined variables`.  It also allows you to
 read the name of a variable from a data file.  If the argument is a numerical
 expression, value() returns the value of that expression.  If the argument is a
 string that does not correspond to a currently defined variable,
 value() returns NaN.

?expressions operators
?operators
 The operators in `gnuplot` are the same as the corresponding operators in the
 C programming language, except that all operators accept integer, real, and
 complex arguments, unless otherwise noted.  The ** operator (exponentiation)
 is supported, as in FORTRAN.

 Parentheses may be used to change order of evaluation.
?expressions operators unary
?operators unary
?unary
 The following is a list of all the unary operators and their usages:

     Symbol      Example    Explanation
       -           -a          unary minus
       +           +a          unary plus (no-operation)
       ~           ~a        * one's complement
       !           !a        * logical negation
       !           a!        * factorial
       $           $3        * call arg/column during `using` manipulation


 (*) Starred explanations indicate that the operator requires an integer
 argument.

 Operator precedence is the same as in Fortran and C.  As in those languages,
 parentheses may be used to change the order of operation.  Thus -2**2 = -4,
 but (-2)**2 = 4.

 The factorial operator returns a real number to allow a greater range.
?expressions operators binary
?operators binary
 The following is a list of all the binary operators and their usages:

     Symbol       Example      Explanation
       **          a**b          exponentiation
       *           a*b           multiplication
       /           a/b           division
       %           a%b         * modulo
       +           a+b           addition
       -           a-b           subtraction
       ==          a==b          equality
       !=          a!=b          inequality
       <           a<b           less than
       <=          a<=b          less than or equal to
       >           a>b           greater than
       >=          a>=b          greater than or equal to
       &           a&b         * bitwise AND
       ^           a^b         * bitwise exclusive OR
       |           a|b         * bitwise inclusive OR
       &&          a&&b        * logical AND
       ||          a||b        * logical OR
       =           a = b         assignment
       ,           (a,b)         serial evaluation
       .           A.B           string concatenation
       eq          A eq B        string equality
       ne          A ne B        string inequality



 (*) Starred explanations indicate that the operator requires integer
 arguments.
 Capital letters A and B indicate that the operator requires string arguments.

 Logical AND (&&) and OR (||) short-circuit the way they do in C.  That is,
 the second `&&` operand is not evaluated if the first is false; the second
 `||` operand is not evaluated if the first is true.

 Serial evaluation occurs only in parentheses and is guaranteed to proceed
 in left to right order.  The value of the rightmost subexpression is returned.
?expressions operators ternary
?operators ternary
?ternary
 There is a single ternary operator:

     Symbol       Example      Explanation
       ?:          a?b:c     ternary operation



 The ternary operator behaves as it does in C.  The first argument (a), which
 must be an integer, is evaluated.  If it is true (non-zero), the second
 argument (b) is evaluated and returned; otherwise the third argument (c) is
 evaluated and returned.

 The ternary operator is very useful both in constructing piecewise functions
 and in plotting points only when certain conditions are met.

 Examples:

 Plot a function that is to equal sin(x) for 0 <= x < 1, 1/x for 1 <= x < 2,
 and undefined elsewhere:
       f(x) = 0<=x && x<1 ? sin(x) : 1<=x && x<2 ? 1/x : 1/0
       plot f(x)
 Note that `gnuplot` quietly ignores undefined values, so the final branch of
 the function (1/0) will produce no plottable points.  Note also that f(x)
 will be plotted as a continuous function across the discontinuity if a line
 style is used.  To plot it discontinuously, create separate functions for the
 two pieces.  (Parametric functions are also useful for this purpose.)

 For data in a file, plot the average of the data in columns 2 and 3 against
 the datum in column 1, but only if the datum in column 4 is non-negative:

       plot 'file' using 1:( $4<0 ? 1/0 : ($2+$3)/2 )

 For an explanation of the `using` syntax, please see `plot datafile using`.
?expressions operators summation
?operators summation
?summation
 A summation expression has the form
       sum [<var> = <start> : <end>] <expression>
 <var> is treated as an integer variable that takes on successive integral
 values from <start> to <end>.  For each of these, the current value of
 <expression> is added to a running total whose final value becomes the value
 of the summation expression.
 Examples:
       print sum [i=1:10] i
           55.
       # Equivalent to plot 'data' using 1:($2+$3+$4+$5+$6+...)
       plot 'data' using 1 : (sum [col=2:MAXCOL] column(col))
 It is not necessary that <expression> contain the variable <var>.
 Although <start> and <end> can be specified as variables or expressions,
 their value cannot be changed dynamically as a side-effect of carrying
 out the summation. If <end> is less than <start> then the value of the
 summation is zero.
?expressions gnuplot-defined
?gnuplot-defined
?gnuplot-defined variables
?GPVAL
?gpval
 Gnuplot maintains a number of read-only variables that reflect the current
 internal state of the program and the most recent plot. These variables begin
 with the prefix "GPVAL_".
 Examples include GPVAL_TERM, GPVAL_X_MIN, GPVAL_X_MAX, GPVAL_Y_MIN.
 Type `show variables all` to display the complete list and current values.
 Values related to axes parameters (ranges, log base) are values used during the
 last plot, not those currently `set`.

 Example:  To calculate the fractional screen coordinates of the point [X,Y]
      GRAPH_X = (X - GPVAL_X_MIN) / (GPVAL_X_MAX - GPVAL_X_MIN)
      GRAPH_Y = (Y - GPVAL_Y_MIN) / (GPVAL_Y_MAX - GPVAL_Y_MIN)
      SCREEN_X = GPVAL_TERM_XMIN + GRAPH_X * (GPVAL_TERM_XMAX - GPVAL_TERM_XMIN)
      SCREEN_Y = GPVAL_TERM_YMIN + GRAPH_Y * (GPVAL_TERM_YMAX - GPVAL_TERM_YMIN)
      FRAC_X = SCREEN_X / GPVAL_TERM_XSIZE
      FRAC_Y = SCREEN_Y / GPVAL_TERM_YSIZE

 The read-only variable GPVAL_ERRNO is set to a non-zero value if any gnuplot
 command terminates early due to an error.  The most recent error message is
 stored in the string variable GPVAL_ERRMSG.  Both GPVAL_ERRNO and GPVAL_ERRMSG
 can be cleared using the command `reset errors`.

 Interactive terminals with `mouse` functionality maintain read-only variables
 with the prefix "MOUSE_".  See `mouse variables` for details.

 The `fit` mechanism uses several variables with names that begin "FIT_".  It
 is safest to avoid using such names.  "FIT_LIMIT", however, is one that you
 may wish to redefine. Under `set fit errorvariables`, the error for each
 fitted parameter will be stored in a variable named like the parameter, but
 with "_err" appended. See the documentation on `fit` for details.

 See `user-defined variables`, `reset errors`, `mouse variables`, and `fit`.

?expressions user-defined
?user-defined variables
?user-defined
?variables
 New user-defined variables and functions of one through twelve variables may
 be declared and used anywhere, including on the `plot` command itself.

 User-defined function syntax:
       <func-name>( <dummy1> {,<dummy2>} ... {,<dummy12>} ) = <expression>

 where <expression> is defined in terms of <dummy1> through <dummy12>.

 User-defined variable syntax:
       <variable-name> = <constant-expression>

 Examples:
       w = 2
       q = floor(tan(pi/2 - 0.1))
       f(x) = sin(w*x)
       sinc(x) = sin(pi*x)/(pi*x)
       delta(t) = (t == 0)
       ramp(t) = (t > 0) ? t : 0
       min(a,b) = (a < b) ? a : b
       comb(n,k) = n!/(k!*(n-k)!)
       len3d(x,y,z) = sqrt(x*x+y*y+z*z)
       plot f(x) = sin(x*a), a = 0.2, f(x), a = 0.4, f(x)

       file = "mydata.inp"
       file(n) = sprintf("run_%d.dat",n)

 The final two examples illustrate a user-defined string variable and a
 user-defined string function.

 Note that the variables `pi` (3.14159...) and `NaN` (IEEE "Not a Number") are
 already defined.  You can redefine these to something else if you really need
 to. The original values can be recovered by setting:

       NaN = GPVAL_NaN
       pi  = GPVAL_pi

 Other variables may be defined under various gnuplot operations like mousing in
 interactive terminals or fitting; see `gnuplot-defined variables` for details.

 You can check for existence of a given variable V by the exists("V")
 expression. For example
       a = 10
       if (exists("a")) print "a is defined"
       if (!exists("b")) print "b is not defined"

 Valid names are the same as in most programming languages: they must begin
 with a letter, but subsequent characters may be letters, digits, or "_".

 Each function definition is made available as a special string-valued
 variable with the prefix 'GPFUN_'.

 Example:
       set label GPFUN_sinc at graph .05,.95

 See `show functions`, `functions`, `gnuplot-defined variables`, `macros`,
 `value`.
?fonts
 Gnuplot does not provide any fonts of its own. It relies on external font
 handling, the details of which unfortunately vary from one terminal type to
 another. Brief documentation of font mechanisms that apply to more than one
 terminal type is given here. For information on font use by other individual
 terminals, see the documentation for that terminal.
?fonts cairo
 Sorry, this section is under construction.
 These terminals find and access fonts using the external fontconfig tool set.
 Please see the
 fontconfig user manual.
 It is usually sufficient in gnuplot to request a font by a generic name and
 size, letting fontconfig substitute a similar font if necessary. The following
 will probably all work:
      set term pdfcairo font "sans,12"
      set term pdfcairo font "Times,12"
      set term pdfcairo font "Times-New-Roman,12"

?gd
?fonts gd
 Font handling for the png, gif, and jpeg terminals is done by the external
 library libgd.  Five basic fonts are provided directly by libgd. These are
 `tiny` (5x8 pixels), `small` (6x12 pixels), `medium`, (7x13 Bold), `large`
 (8x16) or `giant` (9x15 pixels). These fonts cannot be scaled or rotated.
 Use one of these keywords instead of the `font` keyword. E.g.
      set term png tiny

 On most systems libgd also provides access to Adobe Type 1 fonts (*.pfa) and
 TrueType fonts (*.ttf). You must give the name of the font file, not the name
 of the font inside it, in the form "<face> {,<pointsize>}".
 <face> is either the full pathname to the font file, or the first part of a
 filename in one of the directories listed in the GDFONTPATH environmental
 variable. That is, 'set term png font "Face"' will look for a font file named
 either <somedirectory>/Face.ttf or <somedirectory>/Face.pfa.
 For example, if GDFONTPATH contains `/usr/local/fonts/ttf:/usr/local/fonts/pfa`
 then the following pairs of commands are equivalent
      set term png font "arial"
      set term png font "/usr/local/fonts/ttf/arial.ttf"
      set term png font "Helvetica"
      set term png font "/usr/local/fonts/pfa/Helvetica.pfa"
 To request a default font size at the same time:
      set term png font "arial,11"

 Both TrueType and Adobe Type 1 fonts are fully scalable and rotatable.
 If no specific font is requested in the "set term" command, gnuplot checks
 the environmental variable GNUPLOT_DEFAULT_GDFONT to see if there is a
 preferred default font.
?fonts postscript
 PostScript font handling is done by the printer or viewing program.
 Gnuplot can create valid PostScript or encapsulated PostScript (*.eps) even if
 no fonts at all are installed on your computer.  Gnuplot simply refers to the
 font by name in the output file, and assumes that the printer or viewing
 program will know how to find or approximate a font by that name.

 All PostScript printers or viewers should know about the standard set of Adobe
 fonts `Times-Roman`, `Helvetica`, `Courier`, and `Symbol`.  It is likely that
 many additional fonts are also available, but the specific set depends on your
 system or printer configuration. Gnuplot does not know or care about this;
 the output *.ps or *.eps files that it creates will simply refer to whatever
 font names you request.

 Thus
      set term postscript eps font "Times-Roman,12"
 will produce output that is suitable for all printers and viewers.

 On the other hand
      set term postscript eps font "Garamond-Premier-Pro-Italic"
 will produce an output file that contains valid PostScript, but since it
 refers to a specialized font, only some printers or viewers will be able to
 display the specific font that was requested.  Most will substitute a
 different font.

 However, it is possible to embed a specific font in the output file so that
 all printers will be able to use it. This requires that the a suitable font
 description file is available on your system. Note that some font files require
 specific licensing if they are to be embedded in this way.
 See `postscript fontfile` for more detailed description and examples.
?glossary
 Throughout this document an attempt has been made to maintain consistency of
 nomenclature.  This cannot be wholly successful because as `gnuplot` has
 evolved over time, certain command and keyword names have been adopted that
 preclude such perfection.  This section contains explanations of the way
 some of these terms are used.

 A "page" or "screen" or "canvas" is the entire area addressable by `gnuplot`.
 On a desktop it is a full window; on a plotter, it is a single sheet of paper;
 in svga mode it is the full monitor screen.

 A screen may contain one or more "plots".  A plot is defined by an abscissa
 and an ordinate, although these need not actually appear on it, as well as
 the margins and any text written therein.

 A plot contains one "graph".  A graph is defined by an abscissa and an
 ordinate, although these need not actually appear on it.

 A graph may contain one or more "lines".  A line is a single function or
 data set.  "Line" is also a plotting style.  The word will also be used in
 sense "a line of text".  Presumably the context will remove any ambiguity.

 The lines on a graph may have individual names.  These may be listed
 together with a sample of the plotting style used to represent them in
 the "key", sometimes also called the "legend".

 The word "title" occurs with multiple meanings in `gnuplot`.  In this
 document, it will always be preceded by the adjective "plot", "line", or
 "key" to differentiate among them.
 A 2D graph may have up to four labelled `axes`.  The names of the four axes
 are "x" for the axis along the bottom border of the plot, "y" for the axis
 along the left border, "x2" for the top border, and "y2" for the right border.
 See `axes`.

 A 3D graph may have up to three labelled `axes` -- "x", "y" and "z".  It is
 not possible to say where on the graph any particular axis will fall because
 you can change the direction from which the graph is seen with `set view`.

 When discussing data files, the term "record" will be resurrected and used
 to denote a single line of text in the file, that is, the characters between
 newline or end-of-record characters.  A "point" is the datum extracted from
 a single record.  A "datablock" is a set of points from consecutive records,
 delimited by blank records.  A line, when referred to in the context of a
 data file, is a subset of a datablock.
?linetypes
?colors
 Each gnuplot terminal type provides a set of distinct "linetypes". These may
 differ in color, in thickness, in dot/dash pattern, or in some combination of
 color and dot/dash. The default linetypes for a particular terminal can be
 previewed by issuing the `test` command after setting the terminal type.
 The pre-defined colors and dot/dash patterns are not guaranteed to be
 consistent for all terminal types, but all terminals use the special linetype
 -1 to mean a solid line in the primary foreground color (normally black).
 Most terminals also recognize the special linetype "bgnd" to mean a solid line
 in the background color.

 You can redefine the default linetype properties either interactively or via an
 initialization file.  This allows you to customize the colors and other
 properties of the lines used by all gnuplot plotting commands.
 See `set linetype`.  

 By default, successive functions or datafiles plotted by a single command will
 be assigned successive linetypes.  You can override this default sequence by
 specifying a particular linetype for any function, datafile, or plot element.

 Examples:

      plot "foo", "bar"                 # plot two files using linetypes 1, 2
      plot sin(x) linetype 4            # terminal-specific linetype color 4
      plot sin(x) lt -1                 # black

 For many terminal types it is also possible to assign user-defined colors
 using explicit rgb (red, green, blue) values, named colors, or color values
 that refer to the current pm3d palette.

 Examples:

      plot sin(x) lt rgb "violet"       # one of gnuplot's named colors
      plot sin(x) lt rgb "#FF00FF"      # explicit RGB triple in hexadecimal
      plot sin(x) lt palette cb -45     # whatever color corresponds to -45
                                        # in the current cbrange of the palette
      plot sin(x) lt palette frac 0.3   # fractional value along the palette

 See `show colornames`, `set palette`, `cbrange`.

 For terminals that support dot/dash patterns, each default linetype has both
 a dot-dash pattern and a default color. Gnuplot does not currently provide a
 mechanism for changing the dot-dash pattern, so if you want both a particular
 dash pattern and a particular color you must first choose a linetype that has
 the required dash pattern, then override the default color using the keyword 
 `linecolor`, abbreviated `lc`.  For example, the postscript terminal provides
 a dashed blue line as linetype 3.  The plot commands below use this same dash
 pattern for three plots, one in blue (the default), another in red
 (the default for linetype 1), and a third in gold.

 Example:

      set term postscript dashed color
      plot 'foo' lt 3, 'baz' lt 3 linecolor 1, 'bar' lt 3 lc rgb 'gold'

?colorspec
?rgbcolor
?lc
?linecolor
?tc
?textcolor
 Many commands allow you to specify a linetype with an explicit color.
 Terminal-independent color choice is only possible for terminals that support
 RGB color or pm3d palettes.

 Syntax:

       ... {linecolor | lc} {<colorspec> | <n>}
       ... {textcolor | tc} {<colorspec> | {linetype | lt} <n>}

 where <colorspec> has one of the following forms:

       rgbcolor "colorname"
       rgbcolor "#RRGGBB"
       rgbcolor variable       # color is read from input file
       palette frac <val>      # <val> runs from 0 to 1
       palette cb <value>      # <val> lies within cbrange
       palette z
       variable                # color index is read from input file

 The "<n>" is the linetype number the color of which is used, see `test`.

 "colorname" refers to one of the color names built in to gnuplot. For a list
 of the available names, see `show colornames`.

 "#RRGGBB" is a hexadecimal constant preceded by the "#" symbol. The RRGGBB
 represents the red, green, and blue components of the color, each on a scale
 from 0 - 255.  For example, magenta = full-scale red + full-scale blue would
 be represented by #FF00FF, which is the hexadecimal representation of
 (255 << 16) + (0 << 8) + (255).

 The color palette is a linear gradient of colors that smoothly maps a
 single numerical value onto a particular color.  Two such mappings are always
 in effect. `palette frac`  maps a fractional value between 0 and 1 onto the
 full range of the color palette.  `palette cb` maps the range of the color
 axis onto the same palette.  See `set cbrange`.  See also `set colorbox`.
 You can use either of these to select a constant color from the current
 palette.

 "palette z" maps the z value of each plot segment or plot element into the
 cbrange mapping of the palette. This allows smoothly-varying color along a
 3d line or surface. It also allows coloring 2D plots by palette values read
 from an extra column of data (not all 2D plot styles allow an extra column).
?background
?bgnd
 Most terminals now allow you to set an explicit background color for the plot.
 The special linetype `bgnd` will draw in this color, and `bgnd` is also 
 recognized as a color.
 Examples:
      # This will erase a section of the canvas by writing over it in the
      # background color
      set term wxt background rgb "gray75"
      set object 1 rectangle from x0,y0 to x1,y1 fillstyle solid fillcolor bgnd
      # This will draw an "invisible" line along the x axis
      plot 0 lt bgnd
?linecolor variable
?lc variable
?textcolor variable
?tc variable
 `lc variable` tells the program to use the value read from one column of the
 input data as a linetype index, and use the color belonging to that linetype.
 This requires a corresponding additional column in the `using` specifier.
 Text colors can be set similarly using `tc variable`.

 Examples:
       # Use the third column of data to assign colors to individual points
       plot 'data' using 1:2:3 with points lc variable

       # A single data file may contain multiple sets of data, separated by two
       # blank lines.  Each data set is assigned as index value (see `index`)
       # that can be retrieved via the `using` specifier `column(-2)`.
       # See `pseudocolumns`.  This example uses to value in column -2 to 
       # draw each data set in a different line color.
       plot 'data' using 1:2:(column(-2)) with lines lc variable

?rgbcolor variable
?lc rgbcolor variable
?tc rgbcolor variable
 You can assign a separate color for each data point, line segment, or label in
 your plot.  `lc rgbcolor variable` tells the program to read RGB color
 information for each line in the data file. This requires a corresponding
 additional column in the `using` specifier.  The extra column is interpreted as
 a 24-bit packed RGB triple. If the value is provided directly in the data file
 it is easiest to give it as a hexidecimal value (see `rgbcolor`). 
 Alternatively, the `using` specifier can contain an expression that evaluates
 to a 24-bit RGB color as in the example below.
 Text colors are similarly set using `tc rgbcolor variable`.

 Example:
       # Place colored points in 3D at the x,y,z coordinates corresponding to
       # their red, green, and blue components
       rgb(r,g,b) = 65536 * int(r) + 256 * int(g) + int(b)
       splot "data" using 1:2:3:(rgb($1,$2,$3)) with points lc rgb variable

? linestyles vs linetypes
 Lines can have additional properties such as linewidth.  You can associate
 these various properties, as well as equivalent properties for point symbols,
 into user-defined "linestyles" using the command `set style line`.  Once
 you have defined a linestyle, you can use it in a plot command to control
 the appearance of one or more plot elements.

 Whereas `linetypes` are permanent (they last until you explicitly redefine
 them), `linestyles` are temporary.  They only last until the next reset 
 of the graphics state. 

 Examples:

      # define a new line style with terminal-independent color cyan,
      # linewidth 3, and associated point type 6 (a circle with a dot in it).
      set style line 5 lt rgb "cyan" lw 3 pt 6
      plot sin(x) with linespoints ls 5          # user-defined line style 5

?mouse input
 Many terminals allow interaction with the current plot using the mouse. Some
 also support the definition of hotkeys to activate pre-defined functions by
 hitting a single key while the mouse focus is in the active plot window.
 It is even possible to combine mouse input with `batch` command scripts, by
 invoking the command `pause mouse` and then using the mouse variables returned
 by mouse clicking as parameters for subsequent scripted actions.
 See `bind` and `mouse variables`.  See also the command `set mouse`.
?commands bind
?hotkey
?hotkeys
?bind
 Syntax:
       bind {allwindows} [<key-sequence>] ["<gnuplot commands>"]
       bind <key-sequence> ""
       reset bind

 The `bind` allows defining or redefining a hotkey, i.e. a sequence of gnuplot
 commands which will be executed when a certain key or key sequence is pressed
 while the driver's window has the input focus. Note that `bind` is only
 available if gnuplot was compiled with `mouse` support and it is used by all
 mouse-capable terminals. A user-specified binding supersedes any builtin
 bindings, except that <space> and 'q' cannot normally be rebound. For an
 exception, see `bind space`.

 Only mouse button 1 can be bound, and only for 2D plots.

 You get the list of all hotkeys by typing `show bind` or `bind` or by typing
 the hotkey 'h' in the graph window.

 Key bindings are restored to their default state by `reset bind`.

 Note that multikey-bindings with modifiers must be given in quotes.

 Normally hotkeys are only recognized when the currently active plot window
 has focus. `bind allwindows <key> ...` (short form: `bind all <key> ...`)
 causes the binding for <key> to apply to all gnuplot plot windows, active
 or not.  In this case gnuplot variable MOUSE_KEY_WINDOW is set to the ID
 of the originating window, and may be used by the bound command.

 Examples:

 - set bindings:

     bind a "replot"
     bind "ctrl-a" "plot x*x"
     bind "ctrl-alt-a" 'print "great"'
     bind Home "set view 60,30; replot"
     bind all Home 'print "This is window ",MOUSE_KEY_WINDOW'

 - show bindings:
     bind "ctrl-a"          # shows the binding for ctrl-a
     bind                   # shows all bindings
     show bind              # show all bindings

 - remove bindings:
     bind "ctrl-alt-a" ""   # removes binding for ctrl-alt-a
                              (note that builtins cannot be removed)
     reset bind             # installs default (builtin) bindings
     bind!                  # deprecated form of "reset bind"

 - bind a key to toggle something:
   v=0
   bind "ctrl-r" "v=v+1;if(v%2)set term x11 noraise; else set term x11 raise"

 Modifiers (ctrl / alt) are case insensitive, keys not:
     ctrl-alt-a == CtRl-alT-a
     ctrl-alt-a != ctrl-alt-A

 List of modifiers (alt == meta):
     ctrl, alt

 List of supported special keys:

    "BackSpace", "Tab", "Linefeed", "Clear", "Return", "Pause", "Scroll_Lock",
    "Sys_Req", "Escape", "Delete", "Home", "Left", "Up", "Right", "Down",
    "PageUp", "PageDown", "End", "Begin",

    "KP_Space", "KP_Tab", "KP_Enter", "KP_F1", "KP_F2", "KP_F3", "KP_F4",
    "KP_Home", "KP_Left", "KP_Up", "KP_Right", "KP_Down", "KP_PageUp",
    "KP_PageDown", "KP_End", "KP_Begin", "KP_Insert", "KP_Delete", "KP_Equal",
    "KP_Multiply", "KP_Add", "KP_Separator", "KP_Subtract", "KP_Decimal",
    "KP_Divide",

    "KP_1" - "KP_9", "F1" - "F12"

 The following are window events rather than actual keys

    "Button1" "Close"

 See also help for `mouse`.
?commands bind space
?bind space
 If gnuplot was built with configuration option --enable-raise-console, then
 typing <space> in the plot window raises gnuplot's command window. This hotkey
 can be changed to ctrl-space by starting gnuplot as 'gnuplot -ctrlq', or by
 setting the XResource 'gnuplot*ctrlq'.  See `x11 command-line-options`.
?mouse variables
 When `mousing` is active, clicking in the active window will set several user
 variables that can be accessed from the gnuplot command line. The coordinates
 of the mouse at the time of the click are stored in MOUSE_X MOUSE_Y MOUSE_X2
 and MOUSE_Y2. The mouse button clicked, and any meta-keys active at that time,
 are stored in MOUSE_BUTTON MOUSE_SHIFT MOUSE_ALT and MOUSE_CTRL.  These
 variables are set to undefined at the start of every plot, and only become
 defined in the event of a mouse click in the active plot window. To determine
 from a script if the mouse has been clicked in the active plot window, it is
 sufficient to test for any one of these variables being defined.

       plot 'something'
       pause mouse
       if (defined(MOUSE_BUTTON)) call 'something_else'; \
       else print "No mouse click."

 It is also possible to track keystrokes in the plot window using the mousing
 code.

       plot 'something'
       pause mouse keypress
       print "Keystroke ", MOUSE_KEY, " at ", MOUSE_X, " ", MOUSE_Y

 When `pause mouse keypress` is terminated by a keypress, then MOUSE_KEY will
 contain the ascii character value of the key that was pressed. MOUSE_CHAR will
 contain the character itself as a string variable.  If the pause command is
 terminated abnormally (e.g. by ctrl-C or by externally closing the plot window)
 then MOUSE_KEY will equal -1.

 Note that after a zoom by mouse, you can read the new ranges as GPVAL_X_MIN,
 GPVAL_X_MAX, GPVAL_Y_MIN, and GPVAL_Y_MAX, see `gnuplot-defined variables`.


?plotting
 There are three `gnuplot` commands which actually create a plot: `plot`,
 `splot` and `replot`.  `plot` generates 2D plots, `splot` generates 3D
 plots (actually 2D projections, of course), and `replot` appends its
 arguments to the previous `plot` or `splot` and executes the modified
 command.

 Much of the general information about plotting can be found in the discussion
 of `plot`; information specific to 3D can be found in the `splot` section.

 `plot` operates in either rectangular or polar coordinates -- see `set polar`
 for details of the latter.  `splot` operates only in rectangular coordinates,
 but the `set mapping` command allows for a few other coordinate systems to be
 treated.  In addition, the `using` option allows both `plot` and `splot` to
 treat almost any coordinate system you'd care to define.

 `plot` also lets you use each of the four borders -- x (bottom), x2 (top), y
 (left) and y2 (right) -- as an independent axis.  The `axes` option lets you
 choose which pair of axes a given function or data set is plotted against.  A
 full complement of `set` commands exists to give you complete control over
 the scales and labelling of each axis.  Some commands have the name of an
 axis built into their names, such as `set xlabel`.  Other commands have one
 or more axis names as options, such as `set logscale xy`.  Commands and
 options controlling the z axis have no effect on 2D graphs.

 `splot` can plot surfaces and contours in addition to points and/or lines.
 See `set isosamples` for information about defining the grid for a 3D function.
 See `splot datafile` for information about the requisite file structure for 3D
 data values, `set contour` and `set cntrparam` for information about contours.

 In `splot`, control over the scales and labels of the axes are the same as
 with `plot`, except that commands and options controlling the x2 and y2 axes
 have no effect whereas of course those controlling the z axis do take effect.
?startup
?start
?start-up
?initialization
?.gnuplot
 When gnuplot is run, it first looks for a system-wide initialization file named
 `gnuplotrc`.  The location of this file is determined when the program is built
 and is reported by `show loadpath`.  The program then looks in the user's HOME
 directory for a file called `.gnuplot` on Unix-like systems or `GNUPLOT.INI` on
 other systems.  (Windows and OS/2 will look for it in the directory named in
 the environment variable `GNUPLOT`; Windows will use `USERPROFILE` if GNUPLOT
 is not defined).
 Note: The program can be configured to look first in the current directory,
 but this is not recommended because it is bad security practice.
?strings
?string variables
 In addition to string constants, most gnuplot commands also accept a string
 variable, a string expression, or a function that returns a string.
 For example, the following four methods of creating a plot all result in the
 same plot title:

       four = "4"
       graph4 = "Title for plot #4"
       graph(n) = sprintf("Title for plot #%d",n)

       plot 'data.4' title "Title for plot #4"
       plot 'data.4' title graph4
       plot 'data.4' title "Title for plot #".four
       plot 'data.4' title graph(4)

 Since integers are promoted to strings when operated on by the string
 concatenation operator, the following method also works:

       N = 4
       plot 'data.'.N title "Title for plot #".N

 In general, elements on the command line will only be evaluated as possible
 string variables if they are not otherwise recognizable as part of the normal
 gnuplot syntax. So the following sequence of commands is legal, although
 probably should be avoided so as not to cause confusion:

       plot = "my_datafile.dat"
       title = "My Title"
       plot plot title title

 There are three binary operators that require string operands: the string
 concatenation operator ".", the string equality operator "eq" and the string
 inequality operator "ne".  The following example will print TRUE.

      if ("A"."B" eq "AB") print "TRUE"

 See also the two string formatting functions `gprintf` and `sprintf`.

 Substrings can be specified by appending a range specifier to any string,
 string variable, or string-valued function.  The range specifier has the
 form [begin:end], where begin is the index of the first character of the
 substring and end is the index of the last character of the substring.
 The first character has index 1.  The begin or end fields may be empty, or
 contain '*', to indicate the true start or end of the original string.
 E.g.  str[:] and str[*:*] both describe the full string str.
?substitution
 When a command line to gnuplot is first read, i.e. before it is interpreted
 or executed, two forms of lexical substitution are performed. These are
 triggered by the presence of text in backquotes (ascii character 96) or
 preceded by @ (ascii character 64).
?substitution backquotes
?backquotes
?shell commands
 Command-line substitution is specified by a system command enclosed in
 backquotes.  This command is spawned and the output it produces replaces
 the backquoted text on the command line.  Some implementations also support
 pipes;  see `plot datafile special-filenames`.

 Command-line substitution can be used anywhere on the `gnuplot` command
 line, except inside strings delimited by single quotes.

 Example:

 This will run the program `leastsq` and replace `leastsq` (including
 backquotes) on the command line with its output:
       f(x) = `leastsq`

 or, in VMS
       f(x) = `run leastsq`

 These will generate labels with the current time and userid:
       set label "generated on `date +%Y-%m-%d` by `whoami`" at 1,1
       set timestamp "generated on %Y-%m-%d by `whoami`"
?substitution macros
?macros
 Substitution of command line macros is disabled by default, but may be
 enabled using the `set macros` command.  If macro substitution is enabled,
 the character @ is used to trigger substitution of the current value of a
 string variable into the command line. The text in the string variable may
 contain any number of lexical elements.  This allows string variables to be
 used as command line macros.  Only string constants may be expanded using this
 mechanism, not string-valued expressions.
 For example:

       set macros
       style1 = "lines lt 4 lw 2"
       style2 = "points lt 3 pt 5 ps 2"
       range1 = "using 1:3"
       range2 = "using 1:5"
       plot "foo" @range1 with @style1, "bar" @range2 with @style2

 The line containing @ symbols is expanded on input, so that by the time it is
 executed the effect is identical to having typed in full

       plot "foo" using 1:3 with lines lt 4 lw 2, \
            "bar" using 1:5 with points lt 3 pt 5 ps 2

 The function exists() may be useful in connection with macro evaluation.
 The following example checks that C can safely be expanded as the name of
 a user-defined variable:

       C = "pi"
       if (exists(C)) print C," = ", @C

 Macro expansion does not occur inside either single or double quotes.
 However macro expansion does occur inside backquotes.

 Macro expansion is handled as the very first thing the interpreter does when
 looking at a new line of commands and is only done once. Therefore, code like
 the following will execute correctly:

      A = "c=1"
      @A

 but this line will not, since the macro is defined on the same line
 and will not be expanded in time

      A = "c=1"; @A   # will not expand to c=1

 For execution of complete commands the `evaluate` command may also be handy.
?mixing_macros_backquotes
?substitution mixing_macros_backquotes
 The interaction of string variables, backquotes and macro substitution is
 somewhat complicated.  Backquotes do not block macro substitution, so

       filename = "mydata.inp"
       lines = ` wc --lines @filename | sed "s/ .*//" `

 results in the number of lines in mydata.inp being stored in the integer
 variable lines. And double quotes do not block backquote substitution, so

       mycomputer = "`uname -n`"

 results in the string returned by the system command `uname -n` being stored
 in the string variable mycomputer.

 However, macro substitution is not performed inside double quotes, so you
 cannot define a system command as a macro and then use both macro and backquote
 substitution at the same time.

        machine_id = "uname -n"
        mycomputer = "`@machine_id`"  # doesn't work!!

 This fails because the double quotes prevent @machine_id from being interpreted
 as a macro. To store a system command as a macro and execute it later you must
 instead include the backquotes as part of the macro itself.  This is
 accomplished by defining the macro as shown below.  Notice that the sprintf
 format nests all three types of quotes.

       machine_id = sprintf('"`uname -n`"')
       mycomputer = @machine_id
?syntax
?specify
?punctuation
 Options and any accompanying parameters are separated by spaces whereas lists
 and coordinates are separated by commas.  Ranges are separated by colons and
 enclosed in brackets [], text and file names are enclosed in quotes, and a
 few miscellaneous things are enclosed in parentheses.

 Commas are used to separate coordinates on the `set` commands `arrow`,
 `key`, and `label`; the list of variables being fitted (the list after the
 `via` keyword on the `fit` command); lists of discrete contours or the loop
 parameters which specify them on the `set cntrparam` command; the arguments
 of the `set` commands `dgrid3d`, `dummy`, `isosamples`, `offsets`, `origin`,
 `samples`, `size`, `time`, and `view`; lists of tics or the loop parameters
 which specify them; the offsets for titles and axis labels; parametric
 functions to be used to calculate the x, y, and z coordinates on the `plot`,
 `replot` and `splot` commands; and the complete sets of keywords specifying
 individual plots (data sets or functions) on the `plot`, `replot` and `splot`
 commands.

 Parentheses are used to delimit sets of explicit tics (as opposed to loop
 parameters) and to indicate computations in the `using` filter of the `fit`,
 `plot`, `replot` and `splot` commands.

 (Parentheses and commas are also used as usual in function notation.)

 Square brackets are used to delimit ranges given in `set`, `plot`
 or `splot` commands.

 Colons are used to separate extrema in `range` specifications (whether they
 are given on `set`, `plot` or `splot` commands) and to separate entries in
 the `using` filter of the `plot`, `replot`, `splot` and `fit` commands.

 Semicolons are used to separate commands given on a single command line.

 Curly braces are used in the syntax for enhanced text mode and to delimit
 blocks in if/then/else statements.  They are also used to denote complex
 numbers: {3,2} = 3 + 2i.

 The EEPIC, Imagen, Uniplex, LaTeX, and TPIC drivers allow a newline to be
 specified by \\ in a single-quoted string or \\\\ in a double-quoted string.
?quotes
?syntax quotes
 Gnuplot uses three forms of quote marks for delimiting text strings,
 double-quote (ascii 34), single-quote (ascii 39), and backquote (ascii 96).

 Filenames may be entered with either single- or double-quotes.  In this
 manual the command examples generally single-quote filenames and double-quote
 other string tokens for clarity.

 String constants and text strings used for labels, titles, or other plot
 elements may be enclosed in either single quotes or double quotes. Further
 processing of the quoted text depends on the choice of quote marks.

 Backslash processing of special characters like \n (newline) and
 \345 (octal character code) is performed for double-quoted strings.  In
 single-quoted strings, backslashes are just ordinary characters.  To get
 a single-quote (ascii 39) in a single-quoted string, it has to be doubled.
 Thus the strings "d\" s' b\\" and 'd" s'' b\' are completely equivalent.

 Text justification is the same for each line of a multi-line string.
 Thus the center-justified string
       "This is the first line of text.\nThis is the second line."
 will produce
                        This is the first line of text.
                           This is the second line.
 but
       'This is the first line of text.\nThis is the second line.'
 will produce
           This is the first line of text.\nThis is the second line.

 Enhanced text processing is performed for both double-quoted text and
 single-quoted text, but only by terminals supporting this mode.
 See `enhanced text`.

 Back-quotes are used to enclose system commands for substitution into the
 command line.  See `substitution`.
?time/date
 `gnuplot` supports the use of time and/or date information as input data.
 This feature is activated by the commands `set xdata time`, `set ydata time`,
 etc.

 Internally all times and dates are converted to the number of seconds from
 the year 2000.  The command `set timefmt` defines the format for all inputs:
 data files, ranges, tics, label positions---in short, anything that accepts a
 data value must receive it in this format.  Since only one input format can
 be in force at a given time, all time/date quantities being input at the same
 time must be presented in the same format.  Thus if both x and y data in a
 file are time/date, they must be in the same format.

 The conversion to and from seconds assumes Universal Time (which is the same
 as Greenwich Standard Time).  There is no provision for changing the time
 zone or for daylight savings.  If all your data refer to the same time zone
 (and are all either daylight or standard) you don't need to worry about these
 things.  But if the absolute time is crucial for your application, you'll
 need to convert to UT yourself.

 Commands like `show xrange` will re-interpret the integer according to
 `timefmt`.  If you change `timefmt`, and then `show` the quantity again, it
 will be displayed in the new `timefmt`.  For that matter, if you give the
 deactivation command (like `set xdata`), the quantity will be shown in its
 numerical form.

 The commands `set format` or `set tics format` define the format that will be
 used for tic labels, whether or not the specified axis is time/date.

 If time/date information is to be plotted from a file, the `using` option
 _must_ be used on the `plot` or `splot` command.  These commands simply use
 white space to separate columns, but white space may be embedded within the
 time/date string.  If you use tabs as a separator, some trial-and-error may
 be necessary to discover how your system treats them.

 The `time` function can be used to get the current system time. This value
 can be converted to a date string with the `strftime` function, or it can be
 used in conjunction with `timecolumn` to generate relative time/date plots.
 The type of the argument determines what is returned. If the argument is an
 integer, `time` returns the current time as an integer, in seconds from 
 1 Jan 2000. If the argument is real (or complex), the result is real as well.
 The precision of the fractional (sub-second) part depends on your operating
 system. If the argument is a string, it is assumed to be a format string, 
 and it is passed to `strftime` to provide a formatted time/date string.

 The following example demonstrates time/date plotting.

 Suppose the file "data" contains records like

       03/21/95 10:00  6.02e23

 This file can be plotted by

       set xdata time
       set timefmt "%m/%d/%y"
       set xrange ["03/21/95":"03/22/95"]
       set format x "%m/%d"
       set timefmt "%m/%d/%y %H:%M"
       plot "data" using 1:3

 which will produce xtic labels that look like "03/21".

 See `time_specifiers`.
?plotting styles

 There are many plotting styles available in gnuplot.
 They are listed alphabetically below.
 The commands `set style data` and `set style function` change the
 default plotting style for subsequent `plot` and `splot` commands.

 You also have the option to specify the plot style explicitly as part of
 the `plot` or `splot` command.  If you want to mix plot styles within a
 single plot, you must specify the plot style for each component.

 Example:

      plot 'data' with boxes, sin(x) with lines

 Each plot style has its own expected set of data entries in a data file.
 For example by default the `lines` style expects either a single column of
 y values (with implicit x ordering) or a pair of columns with x in the first
 and y in the second.  For more information on how to fine-tune how columns in a
 file are interpreted as plot data, see `using`.

?commands set style boxerrorbars
?set style boxerrorbars
?plotting styles boxerrorbars
?style boxerrorbars
?boxerrorbars
 The `boxerrorbars` style is only relevant to 2D data plotting.  It is a
 combination of the `boxes` and `yerrorbars` styles.  It uses 3, 4, or 5
 columns of data:

      3 columns:  x  y  ydelta
      4 columns:  x  y  ydelta xdelta        # boxwidth != -2
      4 columns:  x  y  ylow  yhigh          # boxwidth == -2
      5 columns:  x  y  ylow  yhigh  xdelta

 The boxwidth will come from the fourth column if the y errors are given as
 "ydelta" and the boxwidth was not previously set to -2.0 (`set boxwidth -2.0`)
 or from the fifth column if the y errors are in the form of "ylow yhigh".  The
 special case  `boxwidth = -2.0` is for four-column data with y errors in the
 form "ylow yhigh".  In this case the boxwidth will be calculated so that each
 box touches the adjacent boxes.  The width will also be calculated in cases
 where three-column data are used.

 An additional (4th, 5th or 6th) input column may be used to provide variable 
 (per-datapoint) color information (see `linecolor` and `rgbcolor variable`).
 The error bar will be drawn in the same color as the border of the box.

 The box height is determined from the y error in the same way as it is for
 the `yerrorbars` style---either from y-ydelta to y+ydelta or from ylow to
 yhigh, depending on how many data columns are provided.
 See also
 errorbar demo.
?commands set style boxes
?set style boxes
?plotting styles boxes
?style boxes
?boxes
 The `boxes` style is only relevant to 2D plotting.  It draws a box centered
 about the given x coordinate that extends from the x axis (not from the graph
 border) to the given y coordinate.  It uses 2 or 3 columns of basic data.
 Additional input columns may be used to provide information such as
 variable line or fill color (see `rgbcolor variable`).

      2 columns:  x  y
      3 columns:  x  y  x_width

 The width of the box is obtained in one of three ways.  If the input data has a
 third column, this will be used to set the width of the box.  If not, if a
 width has been set using the `set boxwidth` command, this will be used.
 If neither of these is available, the width of each box will be calculated
 automatically so that it touches the adjacent boxes.

 The interior of the boxes is drawn according to the current fillstyle.
 See `set style fill` for details.  Alternatively a new fillstyle
 may be specified in the plot command.

 For fillstyle `empty` the box is not filled.

 For fillstyle `solid` the box is filled with a solid rectangle of the
 current drawing color. There is an optional parameter <density> that
 controls the fill density; it runs from 0 (background color) to 1
 (current drawing color).

 For fillstyle `pattern` the box is filled in the current drawing color with
 a pattern, if supported by the terminal driver.

 Examples:

 To plot a data file with solid filled boxes with a small vertical space
 separating them (bargraph):

       set boxwidth 0.9 relative
       set style fill solid 1.0
       plot 'file.dat' with boxes

 To plot a sine and a cosine curve in pattern-filled boxes style:

       set style fill pattern
       plot sin(x) with boxes, cos(x) with boxes

 The sin plot will use pattern 0; the cos plot will use pattern 1.
 Any additional plots would cycle through the patterns supported by the
 terminal driver.

 To specify explicit fillstyles for each dataset:

      plot 'file1' with boxes fs solid 0.25, \
           'file2' with boxes fs solid 0.50, \
           'file3' with boxes fs solid 0.75, \
           'file4' with boxes fill pattern 1, \
           'file5' with boxes fill empty

?plotting styles boxplot
?style boxplot
?boxplot
 Boxplots are a common way to represent a statistical distribution of values.
 Quartile boundaries are determined such that 1/4 of the points have a value
 equal or less than the first quartile boundary, 1/2 of the points have a value
 equal or less than the second quartile (median) value, etc.  A box is drawn
 around the region between the first and third quartiles, with a horizontal line
 at the median value.  Whiskers extend from the box to user-specified limits.
 Points that lie outside these limits are drawn individually.

 Examples

     # Place a boxplot at x coordinate 1.0 representing the y values in column 5
     plot 'data' using (1.0):5

     # Same plot but suppress outliers and force the width of the boxplot to 0.3
     set style boxplot nooutliers
     plot 'data' using (1.0):5:(0.3)

 By default only one boxplot is produced that represents all y values from the
 second column of the using specification. However, an additional (fourth) 
 colunm can be added to the specification. If present, the values of that
 column will be interpreted as the discrete levels of a factor variable.
 As many boxplots will be drawn as there are levels in the factor variable.
 The separation between these boxplots is 1.0 by default, but it can be changed
 by `set style boxplot separation`. By default, the value of the factor variable
 is shown as a tic label below (or above) each boxplot.

 Example

     # Suppose that column 2 of 'data' contains either "control" or "treatment"
     # The following example produces two boxplots, one for each level of the
     # factor
     plot 'data' using (1.0):5:(0):2

 The default width of the box can be set via `set boxwidth <width>` or may be
 specified as an optional 3rd column in the `using` clause of the plot command.
 The first and third columns (x coordinate and width) are normally provided as
 constants rather than as data columns.

 By default the whiskers extend from the ends of the box to the most distant
 point whose y value lies within 1.5 times the interquartile range. By default
 outliers are drawn as circles (point type 7).  The width of the bars at the
 end of the whiskers may be controlled using `set bars`.

 These default properties may be changed using the `set style boxplot` command.
 See `set style boxplot`, `bars`, `boxwidth`, `fillstyle`, `candlesticks`.

?commands set style boxxyerrorbars
?set style boxxyerrorbars
?plotting styles boxxyerrorbars
?style boxxyerrorbars
?boxxyerrorbars
 The `boxxyerrorbars` style is only relevant to 2D data plotting.  It is similar
 to the `xyerrorbars` style except that it draws rectangular areas rather than
 simple crosses.  It uses either 4 or 6 basic columns of input data.
 Additional input columns may be used to provide information such as
 variable line or fill color (see `rgbcolor variable`).

      4 columns:  x  y  xdelta  ydelta
      6 columns:  x  y  xlow  xhigh  ylow  yhigh

 The box width and height are determined from the x and y errors in the same
 way as they are for the `xyerrorbars` style---either from xlow to xhigh and
 from ylow to yhigh, or from x-xdelta to x+xdelta and from y-ydelta to
 y+ydelta, depending on how many data columns are provided.

 An additional (5th or 7th) input column may be used to provide variable 
 (per-datapoint) color information (see `linecolor` and `rgbcolor variable`).

 The interior of the boxes is drawn according to the current fillstyle.
 See `set style fill` and `boxes` for details.  Alternatively a new fillstyle
 may be specified in the plot command.
?commands set style candlesticks
?set style candlesticks
?plotting styles candlesticks
?style candlesticks
?candlesticks
 The `candlesticks` style can be used for 2D data plotting of financial
 data or for generating box-and-whisker plots of statistical data.
 The symbol is a rectangular box, centered horizontally at the x
 coordinate and limited vertically by the opening and closing prices.  A
 vertical line segment at the x coordinate extends up from the top of the
 rectangle to the high price and another down to the low.  The vertical line
 will be unchanged if the low and high prices are interchanged.

 Five columns of basic data are required:

       financial data:   date  open  low  high  close
       whisker plot:     x  box_min  whisker_min  whisker_high  box_high

 The width of the rectangle can be controlled by the `set boxwidth` command.
 For backwards compatibility with earlier gnuplot versions, when the
 boxwidth parameter has not been set then the width of the candlestick
 rectangle is controlled by `set bars <width>`.

 Alternatively, an explicit width for each box-and-whiskers grouping may be
 specified in an optional 6th column of data.  The width must be given in the
 same units as the x coordinate.

 An additional (6th, or 7th if the 6th column is used for width data)
 input column may be used to provide variable (per-datapoint) color
 information (see `linecolor` and `rgbcolor variable`).

 By default the vertical line segments have no crossbars at the top and
 bottom. If you want crossbars, which are typically used for box-and-whisker
 plots, then add the keyword `whiskerbars` to the plot command.  By default
 these whiskerbars extend the full horizontal width of the candlestick, but
 you can modify this by specifying a fraction of the full width.

 The usual convention for financial data is that the rectangle is empty
 if (open < close) and solid fill if (close < open). This is the behavior you
 will get if the current fillstyle is set to "empty". See `fillstyle`.
 If you set the fillstyle to solid or pattern, then this will be used for
 all boxes independent of open and close values.
 See also `set bars` and `financebars`.  See also the
 candlestick
 and
 finance 
 demos.

 Note: To place additional symbols, such as the median value, on a
 box-and-whisker plot requires additional plot commands as in this example:

   # Data columns:X Min 1stQuartile Median 3rdQuartile Max
   set bars 4.0
   set style fill empty
   plot 'stat.dat' using 1:3:2:6:5 with candlesticks title 'Quartiles', \
        ''         using 1:4:4:4:4 with candlesticks lt -1 notitle

   # Plot with crossbars on the whiskers, crossbars are 50% of full width
   plot 'stat.dat' using 1:3:2:6:5 with candlesticks whiskerbars 0.5

 See `set boxwidth`, `set bars`, `set style fill`, and `boxplot`.
?commands set style circles
?set style circles
?plotting styles circles
?style circles
?circles
 The `circles` style plots a circle with an explicit radius at each data point.
 If three columns of data are present, they are interpreted as x, y, radius.
 The radius is always interpreted in the units of the plot's horizontal axis
 (x or x2).  The scale on y and the aspect ratio of the plot are both ignored.
 If only two columns are present, the radius is taken from `set style circle`.
 In this case the radius may be given in graph or screen coordinates.
 By default a full circle will be drawn.  It is possible to plot arc segments
 instead of full circles by specifying a start and end angle in the 4th and 5th
 columns.  An optional 4th or 6th column can specify per-circle color.
 The start and end angles of the circle segments must be specified in degrees.


 Examples:

     # draws circles whose area is proportional to the value in column 3
     set style fill transparent solid 0.2 noborder
     plot 'data' using 1:2:(sqrt($3)) with circles, \
          'data' using 1:2 with linespoints

     # draws Pac-men instead of circles
     plot 'data' using 1:2:(10):(40):(320) with circles

     # draw a pie chart with inline data
     set xrange [-15:15]
     set style fill transparent solid 0.9 noborder
     plot '-' using 1:2:3:4:5:6 with circles lc var
     0    0    5    0    30    1
     0    0    5   30    70    2
     0    0    5   70   120    3
     0    0    5  120   230    4
     0    0    5  230   360    5
     e

 The result is similar to using a `points` plot with variable size points and
 pointstyle 7, except that the circles will scale with the x axis range.
 See also `set object circle` and `fillstyle`.
?plotting styles ellipses
?style ellipses
?ellipses
 The `ellipses` style plots an ellipse at each data point.  This style is
 only relevant for 2D plotting.  Each ellipse is described in terms of its
 center, major and minor diameters, and the angle between its major diameter
 and the x axis.

      2 columns: x y
      3 columns: x y major_diam
      4 columns: x y major_diam minor_diam
      5 columns: x y major_diam minor_diam angle

 If only two input columns are present, they are taken as the coordinates of
 the centers, and the ellipses will be drawn with the default extent
 (see `set style ellipse`).  The orientation of the ellipse, which is
 defined as the angle between the major diameter and the plot's x axis,
 is taken from the default ellipse style (see `set style ellipse`).
 If three input columns are provided, the third column is used for both
 diameters.  The orientation angle defaults to zero.
 If four columns are present, they are interpreted as x, y, major diameter,
 minor diameter.  Note that these are diameters, not radii.
 An optional 5th column may be used to specify the orientation angle 
 in degrees. 
 The ellipses will also be drawn with their default extent if either of the 
 supplied diameters in the 3-4-5 column form is negative.

 In all of the above cases, optional variable color data may be given in an
 additional last (3th, 4th, 5th or 6th) column. See `colorspec` for further
 information.

 By default, the major diameter is interpreted in the units of the plot's
 horizontal axis (x or x2) while the minor diameter in that of the vertical
 (y or y2).  This implies that if the x and y axis scales are not equal,
 then the major/minor diameter ratio will no longer be correct after rotation.
 This behavior can be changed with the `units` keyword, however. 

 There are three alternatives: 
 if `units xy` is included in the plot specification, the axes will be scaled
 as described above. `units xx` ensures that both diameters are interpreted
 in units of the x axis, while `units yy` means that both diameters are
 interpreted in units of the y axis. In the latter two cases the ellipses
 will have the correct aspect ratio, even if the plot is resized.

 If `units` is omitted, the default setting will be used, which is equivalent
 to `units xy`. This can be redefined by `set style ellipse`.

 Example (draws ellipses, cycling through the available line types):

     plot 'data' using 1:2:3:4:(0):0 with ellipses

 See also `set object ellipse`, `set style ellipse` and `fillstyle`.
?commands set style dots
?set style dots
?plotting styles dots
?style dots
?dots
 The `dots` style plots a tiny dot at each point; this is useful for scatter
 plots with many points.  Either 1 or 2 columns of input data are required in
 2D.  Three columns are required in 3D.

 For some terminals (post, pdf) the size of the dot can be controlled by
 changing the linewidth.

      1 column    y         # x is row number
      2 columns:  x  y
      3 columns:  x  y  z   # 3D only (splot)

?commands set style filledcurves
?set style filledcurves
?plotting styles filledcurves
?style filledcurves
?filledcurves
 The `filledcurves` style is only relevant to 2D plotting. Three variants
 are possible. The first two variants require either a function or two columns
 of input data, and may be further modified by the options listed below.

 Syntax:

     plot ... with filledcurves [option]

 where the option can be one of the following

     [closed | {above | below}
     {x1 | x2 | y1 | y2 | r}[=<a>] | xy=<x>,<y>]

 The first variant, `closed`, treats the curve itself as a closed polygon.
 This is the default if there are two columns of input data.

 The second variant is to fill the area between the curve and a given axis,
 a horizontal or vertical line, or a point.

     filledcurves closed   ... just filled closed curve,
     filledcurves x1       ... x1 axis,
     filledcurves x2       ... x2 axis, etc for y1 and y2 axes,
     filledcurves y1=0     ... line y=0 (at y1 axis) ie parallel to x1 axis,
     filledcurves y2=42    ... line y=42 (at y2 axis) ie parallel to x2, etc,
     filledcurves xy=10,20 ... point 10,20 of x1,y1 axes (arc-like shape).
     filledcurves above r=1.5  the area of a polar plot outside radius 1.5

 The third variant requires three columns of input data: the x coordinate and
 two y coordinates corresponding to two curves sampled at the same set of
 x coordinates; the area between the two curves is filled.
 This is the default if there are three or more columns of input data.

      3 columns:  x  y1  y2

 Example of filling the area between two input curves.
 fill between curves demo.

     plot 'data' using 1:2:3 with filledcurves

 The `above` and `below` options apply both to commands of the form
     ... filledcurves above {x1|x2|y1|y2|r}=<val>
 and to commands of the form
     ... using 1:2:3 with filledcurves below
 In either case the option limits the filled area to one side of the bounding
 line or curve.

 Note: Not all terminal types support this plotting mode.

 Zooming a filled curve drawn from a datafile may produce empty or incorrect
 areas because gnuplot is clipping points and lines, and not areas.

 If the values of <a>, <x>, <y> are out of the drawing boundary, then they
 are moved to the graph boundary. Then the actually filled area in the case
 of option xy=<x>,<y> will depend on xrange and yrange.
?commands set style financebars
?set style financebars
?plotting styles financebars
?style financebars
?financebars
 The `financebars` style is only relevant for 2D data plotting of financial
 data.  It requires 1 x coordinate (usually a date) and 4 y values (prices).

      5 columns:   date  open  low  high  close

 An additional (6th) input column may be used to provide variable 
 (per-record) color information (see `linecolor` and `rgbcolor variable`).

 The symbol is a vertical line segment, located horizontally at the x
 coordinate and limited vertically by the high and low prices.  A horizontal
 tic on the left marks the opening price and one on the right marks the
 closing price.  The length of these tics may be changed by `set bars`.  The
 symbol will be unchanged if the high and low prices are interchanged.
 See `set bars` and `candlesticks`, and also the
 finance demo.
?commands set style fsteps
?set style fsteps
?plotting styles fsteps
?style fsteps
?fsteps
 The `fsteps` style is only relevant to 2D plotting.  It connects consecutive
 points with two line segments: the first from (x1,y1) to (x1,y2) and the
 second from (x1,y2) to (x2,y2).  The input column requires are the same as for
 plot styles `lines` and `points`.  The difference between `fsteps` and `steps`
 is that `fsteps` traces first the change in y and then the change in x.
 `steps` traces first the change in x and then the change in y.

 See also
 steps demo.
?commands set style fillsteps
?set style fillsteps
?style fillsteps
?fillsteps
 The `fillsteps` style is exactly like `steps` except that the area between
 the curve and y=0 is filled in the current fill style.  See `steps`.
?commands set style histeps
?set style histeps
?plotting styles histeps
?style histeps
?histeps
 The `histeps` style is only relevant to 2D plotting.  It is intended for
 plotting histograms.  Y-values are assumed to be centered at the x-values;
 the point at x1 is represented as a horizontal line from ((x0+x1)/2,y1) to
 ((x1+x2)/2,y1).  The lines representing the end points are extended so that
 the step is centered on at x.  Adjacent points are connected by a vertical
 line at their average x, that is, from ((x1+x2)/2,y1) to ((x1+x2)/2,y2).
 The input column requires are the same as for plot styles `lines` and `points`.

 If `autoscale` is in effect, it selects the xrange from the data rather than
 the steps, so the end points will appear only half as wide as the others.
 See also
 steps demo.

 `histeps` is only a plotting style; `gnuplot` does not have the ability to
 create bins and determine their population from some data set.
?commands set style histogram
?set style histogram
?style histograms
?plotting styles histograms
?histograms
 The `histograms` style is only relevant to 2D plotting.  It produces a bar
 chart from a sequence of parallel data columns. Each element of the `plot`
 command must specify a single input data source (e.g. one column of the input
 file), possibly with associated tic values or key titles.
 Four styles of histogram layout are currently supported.

       set style histogram clustered {gap <gapsize>}
       set style histogram errorbars {gap <gapsize>} {<linewidth>}
       set style histogram rowstacked
       set style histogram columnstacked

 The default style corresponds to `set style histogram clustered gap 2`.
 In this style, each set of parallel data values is collected into a group of
 boxes clustered at the x-axis coordinate corresponding to their sequential
 position (row #) in the selected datafile columns.  Thus if <n> datacolumns are
 selected, the first cluster is centered about x=1, and contains <n> boxes whose
 heights are taken from the first entry in the corresponding <n> data columns.
 This is followed by a gap and then a second cluster of boxes centered about x=2
 corresponding to the second entry in the respective data columns, and so on.
 The default gap width of 2 indicates that the empty space between clusters is
 equivalent to the width of 2 boxes.  All boxes derived from any one column
 are given the same fill color and/or pattern (see `set style fill`).

 Each cluster of boxes is derived from a single row of the input data file.
 It is common in such input files that the first element of each row is a
 label. Labels from this column may be placed along the x-axis underneath
 the appropriate cluster of boxes with the `xticlabels` option to `using`.

 The `errorbars` style is very similar to the `clustered` style, except that it
 requires additional columns of input for each entry. The first column holds
 the height (y value) of that box, exactly as for the `clustered` style.
      2 columns:        y yerr          bar extends from y-yerr to y+err
      3 columns:        y ymin yman     bar extends from ymin to ymax
 The appearance of the error bars is controlled by the current value of
 `set bars` and by the optional <linewidth> specification.

 Two styles of stacked histogram are supported, chosen by the command
 `set style histogram {rowstacked|columnstacked}`.  In these styles the data
 values from the selected columns are collected into stacks of boxes.
 Positive values stack upwards from y=0; negative values stack downwards.
 Mixed positive and negative values will produce both an upward stack and a
 downward stack.  The default stacking mode is `rowstacked`.

 The `rowstacked` style places a box resting on the x-axis for each
 data value in the first selected column; the first data value results in
 a box a x=1, the second at x=2, and so on.  Boxes corresponding to the
 second and subsequent data columns are layered on top of these, resulting
 in a stack of boxes at x=1 representing the first data value from each
 column, a stack of boxes at x=2 representing the second data value from
 each column, and so on.  All boxes derived from any one column are given the
 same fill color and/or pattern (see `set style fill`).

 The `columnstacked` style is similar, except that each stack of boxes is
 built up from a single data column. Each data value from the first specified
 column yields a box in the stack at x=1, each data value from the second
 specified column yields a box in the stack at x=2, and so on.  In this style
 the color of each box is taken from the row number, rather than the column
 number, of the corresponding data field.

 Box widths may be modified using the `set boxwidth` command.
 Box fill styles may be set using the `set style fill` command.

 Histograms always use the x1 axis, but may use either y1 or y2.
 If a plot contains both histograms and other plot styles, the non-histogram
 plot elements may use either the x1 or the x2 axis.

 Examples:
 Suppose that the input file contains data values in columns 2, 4, 6, ...
 and error estimates in columns 3, 5, 7, ...  This example plots the values
 in columns 2 and 4 as a histogram of clustered boxes (the default style).
 Because we use iteration in the plot command, any number of data columns can
 be handled in a single command. See `iteration`.

       set boxwidth 0.9 relative
       set style data histograms
       set style histogram cluster
       set style fill solid 1.0 border lt -1
       plot for [COL=2:4:2] 'file.dat' using COL

 This will produce a plot with clusters of two boxes (vertical bars) centered
 at each integral value on the x axis.  If the first column of the input file
 contains labels, they may be placed along the x-axis using the variant command

       plot for [COL=2:4:2] 'file.dat' using COL:xticlabels(1)

 If the file contains both magnitude and range information for each value,
 then error bars can be added to the plot.  The following commands will add
 error bars extending from (y-<error>) to (y+<error>), capped by horizontal bar
 ends drawn the same width as the box itself. The error bars and bar ends are
 drawn with linewidth 2, using the border linetype from the current fill style.

       set bars fullwidth
       set style fill solid 1 border lt -1
       set style histogram errorbars gap 2 lw 2
       plot for [COL=2:4:2] 'file.dat' using COL:COL+1

 To plot the same data as a rowstacked histogram.  Just to be different, this
 example lists the separate columns explicitly rather than using iteration.

       set style histogram rowstacked
       plot 'file.dat' using 2, '' using 4:xtic(1)

 This will produce a plot in which each vertical bar corresponds to one row of
 data.  Each vertical bar contains a stack of two segments, corresponding in
 height to the values found in columns 2 and 4 of the datafile.
       

 Finally, the commands

       set style histogram columnstacked
       plot 'file.dat' using 2, '' using 4

 will produce two vertical stacks, one for each column of data.  The stack at
 x=1 will contain a box for each entry in column 2 of the datafile.  The stack
 at x=2 will contain a box for each parallel entry in column 4 of the datafile.
 Because this interchanges gnuplot's usual interpretation of input rows and
 columns, the specification of key titles and x-axis tic labels must also be
 modified accordingly. See the comments given below.

       set style histogram columnstacked
       plot '' u 5:key(1)            # uses first column to generate key titles
       plot '' u 5 title columnhead  # uses first row to generate xtic labels

 Note that the two examples just given present exactly the same data values,
 but in different formats.
?newhistogram
?histograms newhistogram
?plotting style histograms newhistogram
 Syntax:

      newhistogram {"<title>"} {lt <linetype>} {fs <fillstyle>} {at <x-coord>}

 More than one set of histograms can appear in a single plot. In this case you
 can force a gap between them, and a separate label for each set, by using the
 `newhistogram` command.
 For example

       set style histogram  cluster
       plot newhistogram "Set A", 'a' using 1, '' using 2, '' using 3, \
            newhistogram "Set B", 'b' using 1, '' using 2, '' using 3

 The labels "Set A" and "Set B" will appear beneath the respective sets of
 histograms, under the overall x axis label.

 The newhistogram command can also be used to force histogram coloring to
 begin with a specific color (linetype). By default colors will continue to
 increment successively even across histogram boundaries. Here is an example
 using the same coloring for multiple histograms
       plot newhistogram "Set A" lt 4, 'a' using 1, '' using 2, '' using 3, \
            newhistogram "Set B" lt 4, 'b' using 1, '' using 2, '' using 3

 Similarly you can force the next histogram to begin with a specified fillstyle.
 If the fillstyle is set to `pattern`, then the pattern used for filling will
 be incremented automatically.

 The `at <x-coord>` option sets the x coordinate position of the following 
 histogram to <x-coord>. For example

        set style histogram cluster
        set style data histogram
        set style fill solid 1.0 border -1
        set xtic 1 offset character 0,0.3
        plot newhistogram "Set A", \
             'file.dat' u 1 t 1, '' u 2 t 2, \
             newhistogram "Set B" at 8, \
             'file.dat' u 2 t 2, '' u 2 t 2

 will position the second histogram to start at x=8.
?automated
?histograms automated
?styles histograms automated
?plotting styles histograms automated
 If you want to create a histogram from many columns of data in a single file,
 it is very convenient to use the plot iteration feature.  See `iteration`.
 For example, to create stacked histograms of the data in columns 3 through 8

       set style histogram columnstacked
       plot for [i=3:8] "datafile" using i title columnhead
?commands set style image
?set style image
?plotting styles image
?style image
?image
?rgbimage
?rgbalpha
 The `image`, `rgbimage`, and `rgbalpha` plotting styles all project a
 uniformly sampled grid of data values onto a plane  in either 2D or 3D.
 The input data may be an actual bitmapped image, perhaps converted from a
 standard format such as PNG, or a simple array of numerical values.

 This figure illustrates generation of a heat map from an array of scalar values.
 The current palette is used to map each value onto the color assigned to the
 corresponding pixel.
       plot '-' matrix with image
       5 4 3 1 0
       2 2 0 0 1
       0 0 0 1 0
       0 1 2 4 3
       e
       e

 Each pixel (data point) of the input 2D image will become a rectangle or
 parallelipiped in the plot. The coordinates of each data point will determine
 the center of the parallelipiped.  That is, an M x N set of data will form an
 image with M x N pixels.  This is different from the pm3d plotting style, where
 an M x N set of data will form a surface of (M-1) x (N-1) elements.  The scan
 directions for a binary image data grid can be further controlled by additional
 keywords. See `binary keywords flipx`, `keywords center`, and `keywords rotate`.

 Image data can be scaled to fill a particular rectangle within a 2D plot 
 coordinate system by specifying the x and y extent of each pixel.
 See `binary keywords dx` and `dy`. To generate the figure at the right,
 the same input image was placed multiple times, each with a specified dx, dy,
 and origin. The input PNG image of a building is 50x128 pixels.  The tall
 building was drawn by mapping this using `dx=0.5 dy=1.5`.  The short building
 used a mapping `dx=0.5 dy=0.35`.

 The `image` style handles input pixels containing a grayscale or color palette
 value. Thus 2D plots (`plot` command) require 3 columns of data (x,y,value),
 while 3D plots (`splot` command) require 4 columns of data (x,y,z,value).

 The `rgbimage` style handles input pixels that are described by three separate
 values for the red, green, and blue components.  Thus 5D data (x,y,r,g,b) is
 needed for `plot` and 6D data (x,y,z,r,g,b) for `splot`.  The individual red,
 green, and blue components are assumed to lie in the range [0:255].

 The `rgbalpha` style handles input pixels that contain alpha channel 
 (transparency) information in addition to the red, green, and blue components.
 Thus 6D data (x,y,r,g,b,a) is needed for `plot` and 7D data (x,y,z,r,g,b,a)
 for `splot`.  The r, g, b, and alpha components are assumed to lie in the range
 [0:255].
?image transparency
?transparency
?alpha channel
 The `rgbalpha` plotting style assumes that each pixel of input data contains
 an alpha value in the range [0:255].  A pixel with alpha = 0 is purely
 transparent and does not alter the underlying contents of the plot. A pixel
 with alpha = 255 is purely opaque.  All terminal types can handle these two
 extreme cases.  A pixel with 0 < alpha < 255 is partially transparent.
 Only a few terminal types can handle this correctly; other terminals will
 approximate this by treating alpha as being either 0 or 255.
?commands set style image failsafe
?set style image failsafe
?plotting styles image failsafe
?style image failsafe
?image failsafe
?failsafe
 Some terminal drivers provide code to optimize rendering of image data
 within a rectangular 2D area.  However this code is known to be imperfect.
 This optimized code may be disabled by using the keyword `failsafe`. E.g.

       plot 'data' with image failsafe
?commands set style impulses
?set style impulses
?plotting styles impulses
?style impulses
?impulses
 The `impulses` style displays a vertical line from y=0 to the y value of each
 point (2D) or from z=0 to the z value of each point (3D).  Note that the y or z
 values may be negative.  Data from additional columns can be used to control
 the color of each impulse.  To use this style effectively in 3D plots, it is
 useful to choose thick lines (linewidth > 1). This approximates a 3D bar chart.

      1 column:   y
      2 columns:  x  y     # line from [x,0] to [x,y]  (2D)
      3 columns:  x  y  z  # line from [x,y,0] to [x,y,z] (3D)

?commands set style labels
?set style labels
?plotting styles labels
?style labels
?labels
 The `labels` style reads coordinates and text from a data file and places
 the text string at the corresponding 2D or 3D position.  3 or 4 input columns
 of basic data are required.  Additional input columns may be used to provide
 information such as variable font size or text color (see `rgbcolor variable`).

      3 columns:  x  y  string    # 2D version
      4 columns:  x  y  z  string # 3D version

 The font, color, rotation angle and other properties of the printed text
 may be specified as additional command options (see `set label`). The example
 below generates a 2D plot with text labels constructed from the city whose
 name is taken from column 1 of the input file, and whose geographic coordinates
 are in columns 4 and 5. The font size is calculated from the value in column 3,
 in this case the population.

   CityName(String,Size) = sprintf("{/=%d %s}", Scale(Size), String)
   plot 'cities.dat' using 5:4:(CityName(stringcolumn(1),$3)) with labels

 If we did not want to adjust the font to a different size for each city,
 the command would be much simpler:

   plot 'cities.dat' using 5:4:1 with labels font "Times,8"

 The `labels` style can also be used in 3D plots. In this case four input
 column specifiers are required, corresponding to X Y Z and text.

   splot 'datafile' using 1:2:3:4 with labels

 See also `datastrings`, `set style data`.
?commands set style lines
?set style lines
?plotting styles lines
?style lines
?lines
 The `lines` style connects adjacent points with straight line segments.
 It may be used in either 2D or 3D plots. The basic form requires 1, 2, or 3
 columns of input data.
 Additional input columns may be used to provide information such as
 variable line color (see `rgbcolor variable`).

 2D form
      1 column:   y       # implicit x from row number
      2 columns:  x  y
 3D form
      1 column:   z       # implicit x from row, y from index
      3 columns:  x  y  z

 See also `linetype`, `linewidth`, and `linestyle`.
?commands set style linespoints
?commands set style lp
?set style linespoints
?plotting styles linespoints
?set style lp
?style linespoints
?style lp
?linespoints
?lp
?pointinterval
 The `linespoints` style connects adjacent points with straight line segments
 and then goes back to draw a small symbol at each point.  The command
 `set pointsize` may be used to change the default size of the points.
 1 or 2 columns of basic input data are required in 2D plots; 1 or 3 columns are
 required if 3D plots.  See `style lines`.  Additional input columns may be used
 to provide information such as variable point size or line color.

 The `pointinterval` (short form `pi`) property of the linetype can be used to
 control whether or not every point in the plot is given a symbol.  For example,
 'with lp pi 3' will draw line segments through every data point, but will only
 place a symbol on every 3rd point.  A negative value for `pointinterval` will
 erase the portion of line segment that passes underneath the symbol. The size
 of the erased portion is controlled by `set pointintervalbox`.

 `linespoints` may be abbreviated `lp`.
?commands set style points
?set style points
?plotting styles points
?style points
?points
 The `points` style displays a small symbol at each point.  The command `set
 pointsize` may be used to change the default size of the points.
 1 or 2 columns of basic input data are required in 2D plots; 1 or 3 columns are
 required in 3D plots.  See `style lines`.  Additional input columns may be used
 to provide information such as variable point size or variable point color.

 Polar plots are not really a separate plot style but are listed here for
 completeness.  The option `set polar` tells gnuplot to interpret input
 2D coordinates as <angle>,<radius> rather than <x>,<y>.
 Many, but not all, 2D plotting styles work in polar mode.
 The figure shows a combination of plot styles `lines` and `filledcurves`.
 See `set polar`, `set rrange`, `set size square`.

?commands set style steps
?set style steps
?plotting styles steps
?style steps
?steps
 The `steps` style is only relevant to 2D plotting.  It connects consecutive
 points with two line segments: the first from (x1,y1) to (x2,y1) and the
 second from (x2,y1) to (x2,y2).  The input column requires are the same as for
 plot styles `lines` and `points`.  The difference between `fsteps` and `steps`
 is that `fsteps` traces first the change in y and then the change in x.
 `steps` traces first the change in x and then the change in y.  To fill the
 area between the curve and the baseline at y=0, use `fillsteps`.
 See also
 steps demo.

?commands set style rgbalpha
?set style rgbalpha
?plotting styles rgbalpha
?style rgbalpha
 See `image`.
?commands set style rgbimage
?set style rgbimage
?plotting styles rgbimage
?style rgbimage
 See `image`.
?commands set style vectors
?set style vectors
?plotting styles vectors
?style vectors
?vectors
 The 2D `vectors` style draws a vector from (x,y) to (x+xdelta,y+ydelta).
 The 3D `vectors` style is similar, but requires six columns of basic data.
 A small arrowhead is drawn at the end of each vector.

      4 columns:  x  y  xdelta  ydelta
      6 columns:  x  y  z  xdelta  ydelta  zdelta

 In both cases, an additional input column (5th in 2D, 7th in 3D) may be used
 to provide variable (per-datapoint) color information. 
 (see `linecolor` and `rgbcolor variable`).

 splot with vectors is supported only for `set mapping cartesian`.

 The keywords "with vectors" may be followed by an in-line arrow style
 specifications, a reference to a predefined arrow style, or a request to read
 the index of the desired arrow style for each vector from a separate column.
 Note: If you choose "arrowstyle variable" it will fill in all arrow properties
 at the time the corresponding vector is drawn; you cannot mix this keyword with
 other line or arrow style qualifiers in the plot command.

      plot ... with vectors filled heads
      plot ... with vectors arrowstyle 3
      plot ... using 1:2:3:4:5 with vectors arrowstyle variable

 See `arrowstyle` for more details.

 Example:
       plot 'file.dat' using 1:2:3:4 with vectors head filled lt 2
       splot 'file.dat' using 1:2:3:(1):(1):(1) with vectors filled head lw 2

 `set clip one` and `set clip two` affect vectors drawn in 2D.
 Please see `set clip` and `arrowstyle`.
?commands set style xerrorbars
?set style xerrorbars
?plotting styles xerrorbars
?style xerrorbars
?xerrorbars
 The `xerrorbars` style is only relevant to 2D data plots.  `xerrorbars` is
 like `points`, except that a horizontal error bar is also drawn.  At each point
 (x,y), a line is drawn from (xlow,y) to (xhigh,y) or from (x-xdelta,y) to
 (x+xdelta,y), depending on how many data columns are provided.  A tic mark
 is placed at the ends of the error bar (unless `set bars` is used---see
 `set bars` for details).  The basic style requires either 3 or 4 columns:

      3 columns:  x  y  xdelta
      4 columns:  x  y  xlow  xhigh

 An additional input column (4th or 5th) may be used to provide information 
 such as variable point color.

?commands set style xyerrorbars
?set style xyerrorbars
?plotting styles xyerrorbars
?style xyerrorbars
?xyerrorbars
 The `xyerrorbars` style is only relevant to 2D data plots.  `xyerrorbars` is
 like `points`, except that horizontal and vertical error bars are also drawn.
 At each point (x,y), lines are drawn from (x,y-ydelta) to (x,y+ydelta) and
 from (x-xdelta,y) to (x+xdelta,y) or from (x,ylow) to (x,yhigh) and from
 (xlow,y) to (xhigh,y), depending upon the number of data columns provided.  A
 tic mark is placed at the ends of the error bar (unless `set bars` is
 used---see `set bars` for details).  Either 4 or 6 input columns are required.

      4 columns:  x  y  xdelta  ydelta
      6 columns:  x  y  xlow  xhigh  ylow  yhigh

 If data are provided in an unsupported mixed form, the `using` filter on the
 `plot` command should be used to set up the appropriate form.  For example,
 if the data are of the form (x,y,xdelta,ylow,yhigh), then you can use

       plot 'data' using 1:2:($1-$3):($1+$3):4:5 with xyerrorbars

 An additional input column (5th or 7th) may be used to provide variable 
 (per-datapoint) color information. 

?commands set style yerrorbars
?commands set style errorbars
?plotting styles yerrorbars
?plotting styles errorbars
?set style yerrorbars
?set style errorbars
?style yerrorbars
?style errorbars
?yerrorbars
 The `yerrorbars` (or `errorbars`) style is only relevant to 2D data plots.
 `yerrorbars` is like `points`, except that a vertical error bar is also drawn.
 At each point (x,y), a line is drawn from (x,y-ydelta) to (x,y+ydelta) or
 from (x,ylow) to (x,yhigh), depending on how many data columns are provided.
 A tic mark is placed at the ends of the error bar (unless `set bars` is
 used---see `set bars` for details).  Either 3 or 4 input columns are required.

      3 columns:  x  y  ydelta
      4 columns:  x  y  ylow  yhigh

 An additional input column (4th or 5th) may be used to provide information 
 such as variable point color.

 See also
 errorbar demo.
?commands set style xerrorlines
?set style xerrorlines
?plotting styles xerrorlines
?style xerrorlines
?xerrorlines
 The `xerrorlines` style is only relevant to 2D data plots.
 `xerrorlines` is like `linespoints`, except that a horizontal error
 line is also drawn. At each point (x,y), a line is drawn from (xlow,y)
 to (xhigh,y) or from (x-xdelta,y) to (x+xdelta,y), depending on how
 many data columns are provided. A tic mark is placed at the ends of
 the error bar (unless `set bars` is used---see `set bars` for details).
 The basic style requires either 3 or 4 columns:

      3 columns:  x  y  xdelta
      4 columns:  x  y  xlow  xhigh

 An additional input column (4th or 5th) may be used to provide information 
 such as variable point color.

?commands set style xyerrorlines
?set style xyerrorlines
?plotting styles xyerrorlines
?style xyerrorlines
?xyerrorlines
 The `xyerrorlines` style is only relevant to 2D data plots.
 `xyerrorlines` is like `linespoints`, except that horizontal and
 vertical error bars are also drawn. At each point (x,y), lines are
 drawn from (x,y-ydelta) to (x,y+ydelta) and from (x-xdelta,y) to
 (x+xdelta,y) or from (x,ylow) to (x,yhigh) and from (xlow,y) to
 (xhigh,y), depending upon the number of data columns provided. A tic
 mark is placed at the ends of the error bar (unless `set bars` is
 used---see `set bars` for details).  Either 4 or 6 input columns are required.

      4 columns:  x  y  xdelta  ydelta
      6 columns:  x  y  xlow  xhigh  ylow  yhigh

 If data are provided in an unsupported mixed form, the `using` filter on the
 `plot` command should be used to set up the appropriate form.  For example,
 if the data are of the form (x,y,xdelta,ylow,yhigh), then you can use

       plot 'data' using 1:2:($1-$3):($1+$3):4:5 with xyerrorlines

 An additional input column (5th or 7th) may be used to provide variable 
 (per-datapoint) color information. 

?commands set style yerrorlines
?commands set style errorlines
?plotting styles yerrorlines
?plotting styles errorlines
?set style yerrorlines
?set style errorlines
?style yerrorlines
?style errorlines
?yerrorlines
 The `yerrorlines` (or `errorlines`) style is only relevant to 2D data
 plots. `yerrorlines` is like `linespoints`, except that a vertical
 error line is also drawn. At each point (x,y), a line is drawn from
 (x,y-ydelta) to (x,y+ydelta) or from (x,ylow) to (x,yhigh), depending
 on how many data columns are provided. A tic mark is placed at the
 ends of the error bar (see `set bars` for details).
 Either 3 or 4 input columns are required.

      3 columns:  x  y  ydelta
      4 columns:  x  y  ylow  yhigh

 An additional input column (4th or 5th) may be used to provide information 
 such as variable point color.

 See also
 errorbar demo.
?3D (surface) plots
?plotting styles 3d (surface) plots
 Surface plots are generated using the `splot` command rather than the `plot`
 command. The style `with lines` draws a surface made from a grid of lines.
 Solid surfaces can be drawn using the style `with pm3d`.
 Usually the surface is displayed at some arbitrary viewing angle,
 such that it clearly represents a 3D surface.  In this case the X, Y, and Z
 axes are all visible in the plot. The illusion of 3D is enhanced by choosing
 hidden line removal or depth-sorted surface elements.
 See `hidden3d` and `pm3d depthorder`.
 The `splot` command can also calculate and draw contour lines corresponding
 to constant Z values. These contour lines may be drawn onto the surface
 itself, or projected onto the XY plane. See `set contour`.
  
  
  
  
?2D projection (set view map)
?projection
 An important special case of the `splot` command is to map the Z coordinate
 onto a 2D surface by projecting the plot along the Z axis.  See `set view map`.
 This plot mode can be used to generate contour plots and heat maps.
  
  
?commands
 This section lists the commands acceptable to `gnuplot` in alphabetical
 order.  Printed versions of this document contain all commands; the text
 available interactively may not be complete.  Indeed, on some systems there may
 be no commands at all listed under this heading.

 Note that in most cases unambiguous abbreviations for command names and their
 options are permissible, i.e., "`p f(x) w li`" instead of "`plot f(x) with
 lines`".

 In the syntax descriptions, braces ({}) denote optional arguments and a
 vertical bar (|) separates mutually exclusive choices.
?commands cd
?cd
 The `cd` command changes the working directory.

 Syntax:
       cd '<directory-name>'

 The directory name must be enclosed in quotes.

 Examples:
       cd 'subdir'
       cd ".."

 It is recommended that Windows users use single-quotes, because backslash [\]
 has special significance inside double-quotes and has to be escaped.
 For example,
       cd "c:\newdata"
 fails, but
       cd 'c:\newdata'
       cd "c:\\newdata"
 work as expected.
?commands call
?call
 The `call` command is identical to the load command with one exception: you
 can have up to ten additional parameters to the command (delimited according
 to the standard parser rules) which can be substituted into the lines read
 from the file.  As each line is read from the `call`ed input file, it is
 scanned for the sequence `$` (dollar-sign) followed by a digit (0--9).  If
 found, the sequence is replaced by the corresponding parameter from the
 `call` command line.  If the parameter was specified as a string in the
 `call` line, it is substituted without its enclosing quotes.  Sequence `$#`
 is replaced by the number of passed parameters.  `$` followed by any character
 will be that character; e.g. use `$$` to get a single `$`.  Providing more
 than ten parameters on the `call` command line will cause an error.  A
 parameter that was not provided substitutes as nothing.  Files being `call`ed
 may themselves contain `call` or `load` commands.

 Syntax:
       call "<input-file>" <parameter-0> <parm-1> ... <parm-9>

 The name of the input file must be enclosed in quotes, and it is recommended
 that parameters are similarly enclosed in quotes (future versions of gnuplot
 may treat quoted and unquoted arguments differently).

 Example:

 If the file 'calltest.gp' contains the line:
       print "argc=$# p0=$0 p1=$1 p2=$2 p3=$3 p4=$4 p5=$5 p6=$6 p7=x$7x"

 entering the command:
       call 'calltest.gp' "abcd" 1.2 + "'quoted'" -- "$2"

 will display:
       argc=7 p0=abcd p1=1.2 p2=+ p3='quoted' p4=- p5=- p6=$2 p7=xx

 NOTE: there is a clash in syntax with the datafile `using` callback
 operator.  Use `$$n` or `column(n)` to access column n from a datafile inside
 a `call`ed datafile plot.
?commands clear
?clear
 The `clear` command erases the current screen or output device as specified
 by `set output`.  This usually generates a formfeed on hardcopy devices.  Use
 `set terminal` to set the device type.

 For some terminals `clear` erases only the portion of the plotting surface
 defined by `set size`, so for these it can be used in conjunction with `set
 multiplot` to create an inset.

 Example:
       set multiplot
       plot sin(x)
       set origin 0.5,0.5
       set size 0.4,0.4
       clear
       plot cos(x)
       unset multiplot

 Please see `set multiplot`, `set size`, and `set origin` for details of these
 commands.
?commands do
?do
 Syntax:
       do for <iteration-spec> {
            <commands>
            <commands>
       }
 Execute a sequence of commands multiple times.  The commands must be enclosed
 in curly brackets, and the opening "{" must be on the same line as the `do`
 keyword.  This command cannot be used with old-style (un-bracketed) if/else
 statements.  See `if`.  For examples of iteration specifiers, see `iteration`.
 Example:
       set multiplot layout 2,2
       do for [name in "A B C D"] {
           filename = name . ".dat"
           set title sprintf("Condition %s",name)
           plot filename title name
       }
       unset multiplot
?commands evaluate
?evaluate
 The `evaluate` command executes the commands given as an argument string.
 Newline characters are not allowed within the string.

 Syntax:
       eval <string expression>

 This is especially useful for a repetition of similar commands.

 Example:
       set_label(x, y, text) \
         = sprintf("set label '%s' at %f, %f point pt 5", text, x, y)
       eval set_label(1., 1., 'one/one')
       eval set_label(2., 1., 'two/one')
       eval set_label(1., 2., 'one/two')

 Please see `substitution macros` for another way to execute commands
 from a string.
?commands exit
?exit
 The commands `exit` and `quit`, as well as the END-OF-FILE character (usually
 Ctrl-D) terminate input from the current input stream: terminal session, pipe,
 and file input (pipe).

 If input streams are nested (inherited `load` scripts), then reading will
 continue in the parent stream. When the top level stream is closed, the
 program itself will exit.

 The command `exit gnuplot` will immediately and unconditionally cause gnuplot
 to exit even if the input stream is multiply nested.  In this case any open
 output files may not be completed cleanly. Example of use:

       bind "ctrl-x" "unset output; exit gnuplot"

 See help for `batch/interactive` for more details.
?commands fit
?fit
?least-squares
?Marquardt
 The `fit` command can fit a user-supplied expression to a set of data points
 (x,z) or (x,y,z), using an implementation of the nonlinear least-squares
 (NLLS) Marquardt-Levenberg algorithm.  Any user-defined variable occurring in
 the expression may serve as a fit parameter, but the return type of the
 expression must be real.

 Syntax:
       fit {<ranges>} <expression>
           '<datafile>' {datafile-modifiers}
           via '<parameter file>' | <var1>{,<var2>,...}

 Ranges may be specified to temporarily limit the data which is to be fitted;
 any out-of-range data points are ignored. The syntax is
       [{dummy_variable=}{<min>}{:<max>}],
 analogous to `plot`; see `plot ranges`.

 <expression> is any valid `gnuplot` expression, although it is usual to use a
 previously user-defined function of the form f(x) or f(x,y).

 <datafile> is treated as in the `plot` command.  All the `plot datafile`
 modifiers (`using`, `every`,...) except `smooth` and the deprecated `thru`
 are applicable to `fit`. See `plot datafile`.

 The default data formats for fitting functions with a single
 independent variable, z=f(x), are z or x:z.  That is, if there is
 only a single column then it is the dependent variable and the line
 numbers is the independent variable.  If there are two columns, the
 first is the independent variable and the second is the dependent
 variable.

 Those formats can be changed with the datafile `using` qualifier, for
 example to take the z value from a different column or to calculate
 it from several columns.  A third `using` qualifier (a column number
 or an expression), if present, is interpreted as the standard
 deviation of the corresponding z value and is used to compute a
 weight for the datum, 1/s**2.  Otherwise, all data points are
 weighted equally, with a weight of one. Note that if you don't
 specify a `using` option at all, no z standard deviations are read
 from the datafile even if it does have a third column, so you'll
 always get unit weights.

 To fit a function with two independent variables, z=f(x,y), the required
 format is `using` with four items, x:y:z:s.  The complete format must be
 given---no default columns are assumed for a missing token.  Weights for
 each data point are evaluated from 's' as above.  If error estimates are
 not available, a constant value can be specified as a constant expression
 (see `plot datafile using`), e.g., `using 1:2:3:(1)`.

 The fit function may have up to five independent variables.  There
 must be two more `using` qualifiers than there are independent
 variables, unless there is only one variable.  The allowed formats,
 and the default dummy variable names, are as follows:

       z
       x:z
       x:z:s
       x:y:z:s
       x:y:t:z:s
       x:y:t:u:z:s
       x:y:t:u:v:z:s

 The dummy variable names may be changed with ranges as noted above.
 The first range corresponds to the first `using` spec, etc.  A range
 may also be given for z (the dependent variable), but that name
 cannot be changed.

 Multiple datasets may be simultaneously fit with functions of one
 independent variable by making y a 'pseudo-variable', e.g., the dataline
 number, and fitting as two independent variables.  See `fit multi-branch`.

 The `via` qualifier specifies which parameters are to be adjusted, either
 directly, or by referencing a parameter file.

 Examples:
       f(x) = a*x**2 + b*x + c
       g(x,y) = a*x**2 + b*y**2 + c*x*y
       FIT_LIMIT = 1e-6
       fit f(x) 'measured.dat' via 'start.par'
       fit f(x) 'measured.dat' using 3:($7-5) via 'start.par'
       fit f(x) './data/trash.dat' using 1:2:3 via a, b, c
       fit g(x,y) 'surface.dat' using 1:2:3:(1) via a, b, c
       fit a0 + a1*x/(1 + a2*x/(1 + a3*x)) 'measured.dat' via a0,a1,a2,a3
       fit a*x + b*y 'surface.dat' using 1:2:3:(1) via a,b
       fit [*:*][yaks=*:*] a*x+b*yaks 'surface.dat' u 1:2:3:(1) via a,b
       fit a*x + b*y + c*t 'foo.dat' using 1:2:3:4:(1) via a,b,c
       h(x,y,t,u,v) = a*x + b*y + c*t + d*u + e*v
       fit h(x,y,t,u,v) 'foo.dat' using 1:2:3:4:5:6:(1) via a,b,c,d,e

 After each iteration step, detailed information about the current state
 of the fit is written to the display.  The same information about the
 initial and final states is written to a log file, "fit.log".  This file
 is always appended to, so as to not lose any previous fit history;  it
 should be deleted or renamed as desired. By using the command
 `set fit logfile`, the name of the log file can be changed.

 If gnuplot was built with this option, and you activated it using `set fit
 errorvariables`, the error for each fitted parameter will be stored in
 a variable named like the parameter, but with "_err" appended.  Thus the
 errors can be used as input for further computations.

 The fit may be interrupted by pressing Ctrl-C.
 After the current iteration completes, you have the option to
 (1) stop the fit and accept the current parameter values,
 (2) continue the fit, (3) execute a `gnuplot` command as specified by the
 environment variable FIT_SCRIPT.  The default for FIT_SCRIPT is `replot`,
 so if you had previously plotted both the data and the fitting function in
 one graph, you can display the current state of the fit.

 Once `fit` has finished, the `update` command may be used to store final
 values in a file for subsequent use as a parameter file.   See `update`
 for details.
?commands fit parameters
?fit parameters
?commands fit adjustable_parameters
?fit adjustable_parameters
?fit_parameters
 There are two ways that `via` can specify the parameters to be adjusted,
 either directly on the command line or indirectly, by referencing a
 parameter file.  The two use different means to set initial values.

 Adjustable parameters can be specified by a comma-separated list of variable
 names after the `via` keyword.  Any variable that is not already defined
 is created with an initial value of 1.0.  However, the fit is more likely
 to converge rapidly if the variables have been previously declared with more
 appropriate starting values.

 In a parameter file, each parameter to be varied and a corresponding initial
 value are specified, one per line, in the form
       varname = value

 Comments, marked by '#', and blank lines are permissible.  The
 special form
       varname = value       # FIXED

 means that the variable is treated as a 'fixed parameter', initialized by the
 parameter file, but not adjusted by `fit`.  For clarity, it may be useful to
 designate variables as fixed parameters so that their values are reported by
 `fit`.  The keyword `# FIXED` has to appear in exactly this form.

?commands fit beginners_guide
?fit beginners_guide
?fit guide
?fitting
 `fit` is used to find a set of parameters that 'best' fits your data to your
 user-defined function.  The fit is judged on the basis of the sum of the
 squared differences or 'residuals' (SSR) between the input data points and
 the function values, evaluated at the same places.  This quantity is often
 called 'chisquare' (i.e., the Greek letter chi, to the power of 2).  The
 algorithm attempts to minimize SSR, or more precisely, WSSR, as the residuals
 are 'weighted' by the input data errors (or 1.0) before being squared;
 see `fit error_estimates` for details.

 That's why it is called 'least-squares fitting'.  Let's look at an example
 to see what is meant by 'non-linear', but first we had better go over some
 terms.  Here it is convenient to use z as the dependent variable for
 user-defined functions of either one independent variable, z=f(x), or two
 independent variables, z=f(x,y).  A parameter is a user-defined variable
 that `fit` will adjust, i.e., an unknown quantity in the function
 declaration.  Linearity/non-linearity refers to the relationship of the
 dependent variable, z, to the parameters which `fit` is adjusting, not of
 z to the independent variables, x and/or y.  (To be technical, the
 second {and higher} derivatives of the fitting function with respect to
 the parameters are zero for a linear least-squares problem).

 For linear least-squares (LLS), the user-defined function will be a sum of
 simple functions, not involving any parameters, each multiplied by one
 parameter.  NLLS handles more complicated functions in which parameters can
 be used in a large number of ways.  An example that illustrates the
 difference between linear and nonlinear least-squares is the Fourier series.
 One member may be written as
      z=a*sin(c*x) + b*cos(c*x).
 If a and b are the unknown parameters and c is constant, then estimating
 values of the parameters is a linear least-squares problem.  However, if
 c is an unknown parameter, the problem is nonlinear.

 In the linear case, parameter values can be determined by comparatively
 simple linear algebra, in one direct step.  However LLS is a special case
 which is also solved along with more general NLLS problems by the iterative
 procedure that `gnuplot` uses.  `fit` attempts to find the minimum by doing
 a search.  Each step (iteration) calculates WSSR with a new set of parameter
 values.  The Marquardt-Levenberg algorithm selects the parameter values for
 the next iteration.  The process continues until a preset criterion is met,
 either (1) the fit has "converged" (the relative change in WSSR is less than
 FIT_LIMIT), or (2) it reaches a preset iteration count limit, FIT_MAXITER
 (see `fit control variables`).  The fit may also be interrupted
 and subsequently halted from the keyboard (see `fit`).  The user variable
 FIT_CONVERGED contains 1 if the previous fit command terminated due to
 convergence; it contains 0 if the previous fit terminated for any other
 reason.

 Often the function to be fitted will be based on a model (or theory) that
 attempts to describe or predict the behaviour of the data.  Then `fit` can
 be used to find values for the free parameters of the model, to determine
 how well the data fits the model, and to estimate an error range for each
 parameter.  See `fit error_estimates`.

 Alternatively, in curve-fitting, functions are selected independent of
 a model (on the basis of experience as to which are likely to describe
 the trend of the data with the desired resolution and a minimum number
 of parameters*functions.)  The `fit` solution then provides an analytic
 representation of the curve.

 However, if all you really want is a smooth curve through your data points,
 the `smooth` option to `plot` may be what you've been looking for rather
 than `fit`.
?commands fit error_estimates
?fit error_estimates
?fit errors
 In `fit`, the term "error" is used in two different contexts, data error
 estimates and parameter error estimates.

 Data error estimates are used to calculate the relative weight of each data
 point when determining the weighted sum of squared residuals, WSSR or
 chisquare.  They can affect the parameter estimates, since they determine
 how much influence the deviation of each data point from the fitted function
 has on the final values.  Some of the `fit` output information, including
 the parameter error estimates, is more meaningful if accurate data error
 estimates have been provided.

 The 'statistical overview' describes some of the `fit` output and gives some
 background for the 'practical guidelines'.
?commands fit error statistical_overview
?fit error statistical_overview
?statistical_overview
 The theory of non-linear least-squares (NLLS) is generally described in terms
 of a normal distribution of errors, that is, the input data is assumed to be
 a sample from a population having a given mean and a Gaussian (normal)
 distribution about the mean with a given standard deviation.  For a sample of
 sufficiently large size, and knowing the population standard deviation, one
 can use the statistics of the chisquare distribution to describe a "goodness
 of fit" by looking at the variable often called "chisquare".  Here, it is
 sufficient to say that a reduced chisquare (chisquare/degrees of freedom,
 where degrees of freedom is the number of datapoints less the number of
 parameters being fitted) of 1.0 is an indication that the weighted sum of
 squared deviations between the fitted function and the data points is the
 same as that expected for a random sample from a population characterized by
 the function with the current value of the parameters and the given standard
 deviations.

 If the standard deviation for the population is not constant, as in counting
 statistics where variance = counts, then each point should be individually
 weighted when comparing the observed sum of deviations and the expected sum
 of deviations.

 At the conclusion `fit` reports 'stdfit', the standard deviation of the fit,
 which is the rms of the residuals, and the variance of the residuals, also
 called 'reduced chisquare' when the data points are weighted.  The number of
 degrees of freedom (the number of data points minus the number of fitted
 parameters) is used in these estimates because the parameters used in
 calculating the residuals of the datapoints were obtained from the same data.
 These values are exported to the variables
       FIT_NDF = Number of degrees of freedom
       FIT_WSSR = Weighted sum-of-squares residual
       FIT_STDFIT = sqrt(WSSR/NDF)

 To estimate confidence levels for the parameters, one can use the minimum
 chisquare obtained from the fit and chisquare statistics to determine the
 value of chisquare corresponding to the desired confidence level, but
 considerably more calculation is required to determine the combinations of
 parameters which produce such values.

 Rather than determine confidence intervals, `fit` reports parameter error
 estimates which are readily obtained from the variance-covariance matrix
 after the final iteration.  By convention, these estimates are called
 "standard errors" or "asymptotic standard errors", since they are calculated
 in the same way as the standard errors (standard deviation of each parameter)
 of a linear least-squares problem, even though the statistical conditions for
 designating the quantity calculated to be a standard deviation are not
 generally valid for the NLLS problem.  The asymptotic standard errors are
 generally over-optimistic and should not be used for determining confidence
 levels, but are useful for qualitative purposes.

 The final solution also produces a correlation matrix indicating correlation of
 parameters in the region of the solution; The main diagonal elements,
 autocorrelation, are always 1; if all parameters were independent, the
 off-diagonal elements would be nearly 0.  Two variables which completely
 compensate each other would have an off-diagonal element of unit magnitude,
 with a sign depending on whether the relation is proportional or inversely
 proportional.  The smaller the magnitudes of the off-diagonal elements, the
 closer the estimates of the standard deviation of each parameter would be to
 the asymptotic standard error.
?commands fit error practical_guidelines
?fit error practical_guidelines
?practical_guidelines
?guidelines
 If you have a basis for assigning weights to each data point, doing so lets
 you make use of additional knowledge about your measurements, e.g., take into
 account that some points may be more reliable than others.  That may affect
 the final values of the parameters.

 Weighting the data provides a basis for interpreting the additional `fit`
 output after the last iteration.  Even if you weight each point equally,
 estimating an average standard deviation rather than using a weight of 1
 makes WSSR a dimensionless variable, as chisquare is by definition.

 Each fit iteration will display information which can be used to evaluate
 the progress of the fit.  (An '*' indicates that it did not find a smaller
 WSSR and is trying again.)  The 'sum of squares of residuals', also called
 'chisquare', is the WSSR between the data and your fitted function; `fit`
 has minimized that.  At this stage, with weighted data, chisquare is expected
 to approach the number of degrees of freedom (data points minus parameters).
 The WSSR can be used to calculate the reduced chisquare (WSSR/ndf) or stdfit,
 the standard deviation of the fit, sqrt(WSSR/ndf).  Both of these are
 reported for the final WSSR.

 If the data are unweighted, stdfit is the rms value of the deviation of the
 data from the fitted function, in user units.

 If you supplied valid data errors, the number of data points is large enough,
 and the model is correct, the reduced chisquare should be about unity.  (For
 details, look up the 'chi-squared distribution' in your favourite statistics
 reference.)  If so, there are additional tests, beyond the scope of this
 overview, for determining how well the model fits the data.

 A reduced chisquare much larger than 1.0 may be due to incorrect data error
 estimates, data errors not normally distributed, systematic measurement
 errors, 'outliers', or an incorrect model function.  A plot of the residuals,
 e.g., `plot 'datafile' using 1:($2-f($1))`, may help to show any systematic
 trends.  Plotting both the data points and the function may help to suggest
 another model.

 Similarly, a reduced chisquare less than 1.0 indicates WSSR is less than that
 expected for a random sample from the function with normally distributed
 errors.  The data error estimates may be too large, the statistical
 assumptions may not be justified, or the model function may be too general,
 fitting fluctuations in a particular sample in addition to the underlying
 trends.  In the latter case, a simpler function may be more appropriate.

 You'll have to get used to both `fit` and the kind of problems you apply it
 to before you can relate the standard errors to some more practical estimates
 of parameter uncertainties or evaluate the significance of the correlation
 matrix.

 Note that `fit`, in common with most NLLS implementations, minimizes the
 weighted sum of squared distances (y-f(x))**2.  It does not provide any means
 to account for "errors" in the values of x, only in y.  Also, any "outliers"
 (data points outside the normal distribution of the model) will have an
 exaggerated effect on the solution.
?commands fit control
?fit control
 There are a number of `gnuplot` variables that can be defined to affect
 `fit`.  Those which can be defined once `gnuplot` is running are listed
 under 'control_variables' while those defined before starting `gnuplot`
 are listed under 'environment_variables'.
?commands fit control variables
?fit control variables
 The default epsilon limit (1e-5) may be changed by declaring a value for
       FIT_LIMIT
 When the sum of squared residuals changes between two iteration steps by
 a factor less than this number (epsilon), the fit is considered to have
 'converged'.

 The maximum number of iterations may be limited by declaring a value for
       FIT_MAXITER
 A value of 0 (or not defining it at all)  means that there is no limit.

 If you need even more control about the algorithm, and know the
 Marquardt-Levenberg algorithm well, there are some more variables to
 influence it. The startup value of `lambda` is normally calculated
 automatically from the ML-matrix, but if you want to, you may provide
 your own one with
       FIT_START_LAMBDA
 Specifying FIT_START_LAMBDA as zero or less will re-enable the automatic
 selection. The variable
       FIT_LAMBDA_FACTOR
 gives the factor by which `lambda` is increased or decreased whenever
 the chi-squared target function increased or decreased significantly.
 Setting FIT_LAMBDA_FACTOR to zero re-enables the default factor of
 10.0.

 Other variables with the FIT_ prefix may be added to `fit`, so it is safer
 not to use that prefix for user-defined variables.

 The variables FIT_SKIP and FIT_INDEX were used by earlier releases of
 `gnuplot` with a 'fit' patch called `gnufit` and are no longer available.
 The datafile `every` modifier provides the functionality of FIT_SKIP.
 FIT_INDEX was used for multi-branch fitting, but multi-branch fitting of
 one independent variable is now done as a pseudo-3D fit in which the
 second independent variable and `using` are used to specify the branch.
 See `fit multi-branch`.
?commands fit control environment
?fit control environment
 The environment variables must be defined before `gnuplot` is executed; how
 to do so depends on your operating system.

       FIT_LOG
 changes the name (and/or path) of the file to which the fit log will be
 written from the default of "fit.log" in the working directory. The default
 value can be overwritten using the command `set fit logfile`.

       FIT_SCRIPT
 specifies a command that may be executed after an user interrupt. The default
 is `replot`, but a `plot` or `load` command may be useful to display a plot
 customized to highlight the progress of the fit.
?commands fit multi-branch
?fit multi-branch
?multi-branch
?branch
 In multi-branch fitting, multiple data sets can be simultaneously fit with
 functions of one independent variable having common parameters by minimizing
 the total WSSR.  The function and parameters (branch) for each data set are
 selected by using a 'pseudo-variable', e.g., either the dataline number (a
 'column' index of -1) or the datafile index (-2), as the second independent
 variable.

 Example:  Given two exponential decays of the form, z=f(x), each describing
 a different data set but having a common decay time, estimate the values of
 the parameters.  If the datafile has the format x:z:s, then
      f(x,y) = (y==0) ? a*exp(-x/tau) : b*exp(-x/tau)
      fit f(x,y) 'datafile' using  1:-2:2:3  via a, b, tau

 For a more complicated example, see the file "hexa.fnc" used by the
 "fit.dem" demo.

 Appropriate weighting may be required since unit weights may cause one
 branch to predominate if there is a difference in the scale of the dependent
 variable.  Fitting each branch separately, using the multi-branch solution
 as initial values, may give an indication as to the relative effect of each
 branch on the joint solution.
?commands fit starting_values
?fit starting_values
?starting_values
 Nonlinear fitting is not guaranteed to converge to the global optimum (the
 solution with the smallest sum of squared residuals, SSR), and can get stuck
 at a local minimum.  The routine has no way to determine that;  it is up to
 you to judge whether this has happened.

 `fit` may, and often will get "lost" if started far from a solution, where
 SSR is large and changing slowly as the parameters are varied, or it may
 reach a numerically unstable region (e.g., too large a number causing a
 floating point overflow) which results in an "undefined value" message
 or `gnuplot` halting.

 To improve the chances of finding the global optimum, you should set the
 starting values at least roughly in the vicinity of the solution, e.g.,
 within an order of magnitude, if possible.  The closer your starting values
 are to the solution, the less chance of stopping at another minimum.  One way
 to find starting values is to plot data and the fitting function on the same
 graph and change parameter values and `replot` until reasonable similarity
 is reached.  The same plot is also useful to check whether the fit stopped at
 a minimum with a poor fit.

 Of course, a reasonably good fit is not proof there is not a "better" fit (in
 either a statistical sense, characterized by an improved goodness-of-fit
 criterion, or a physical sense, with a solution more consistent with the
 model.)  Depending on the problem, it may be desirable to `fit` with various
 sets of starting values, covering a reasonable range for each parameter.
?commands fit tips
?fit tips
?tips
 Here are some tips to keep in mind to get the most out of `fit`.  They're not
 very organized, so you'll have to read them several times until their essence
 has sunk in.

 The two forms of the `via` argument to `fit` serve two largely distinct
 purposes.  The `via "file"` form is best used for (possibly unattended) batch
 operation, where you just supply the startup values in a file and can later
 use `update` to copy the results back into another (or the same) parameter
 file.

 The `via var1, var2, ...` form is best used interactively, where the command
 history mechanism may be used to edit the list of parameters to be fitted or
 to supply new startup values for the next try.  This is particularly useful
 for hard problems, where a direct fit to all parameters at once won't work
 without good starting values.  To find such, you can iterate several times,
 fitting only some of the parameters, until the values are close enough to the
 goal that the final fit to all parameters at once will work.

 Make sure that there is no mutual dependency among parameters of the function
 you are fitting.  For example, don't try to fit a*exp(x+b), because
 a*exp(x+b)=a*exp(b)*exp(x).  Instead, fit either a*exp(x) or exp(x+b).

 A technical issue:  the parameters must not be too different in magnitude.
 The larger the ratio of the largest and the smallest absolute parameter
 values, the slower the fit will converge.  If the ratio is close to or above
 the inverse of the machine floating point precision, it may take next to
 forever to converge, or refuse to converge at all.  You will have to adapt
 your function to avoid this, e.g., replace 'parameter' by '1e9*parameter' in
 the function definition, and divide the starting value by 1e9.

 If you can write your function as a linear combination of simple functions
 weighted by the parameters to be fitted, by all means do so.  That helps a
 lot, because the problem is no longer nonlinear and should converge with only
 a small number of iterations, perhaps just one.

 Some prescriptions for analysing data, given in practical experimentation
 courses, may have you first fit some functions to your data, perhaps in a
 multi-step process of accounting for several aspects of the underlying
 theory one by one, and then extract the information you really wanted from
 the fitting parameters of those functions.  With `fit`, this may often be
 done in one step by writing the model function directly in terms of the
 desired parameters.  Transforming data can also quite often be avoided,
 though sometimes at the cost of a more difficult fit problem.  If you think
 this contradicts the previous paragraph about simplifying the fit function,
 you are correct.

 A "singular matrix" message indicates that this implementation of the
 Marquardt-Levenberg algorithm can't calculate parameter values for the next
 iteration.  Try different starting values, writing the function in another
 form, or a simpler function.

 Finally, a nice quote from the manual of another fitting package (fudgit),
 that kind of summarizes all these issues:  "Nonlinear fitting is an art!"
?commands help
?help
 The `help` command displays built-in help. To specify information on a
 particular topic use the syntax:

       help {<topic>}

 If <topic> is not specified, a short message is printed about `gnuplot`.
 After help for the requested topic is given, a menu of subtopics is given;
 help for a subtopic may be requested by typing its name, extending the help
 request.  After that subtopic has been printed, the request may be extended
 again or you may go back one level to the previous topic.  Eventually, the
 `gnuplot` command line will return.

 If a question mark (?) is given as the topic, the list of topics currently
 available is printed on the screen.
?commands history
?history
 `history` command lists or saves previous entries in the history of the
 command line editing, or executes an entry.

 Here you find 'usage by examples':

       history               # show the complete history
       history 5             # show last 5 entries in the history
       history quiet 5       # show last 5 entries without entry numbers
       history "hist.gp"     # write the complete history to file hist.gp
       history "hist.gp" append # append the complete history to file hist.gp
       history 10 "hist.gp"  # write last 10 commands to file hist.gp
       history 10 "|head -5 >>diary.gp" # write 5 history commands using pipe
       history ?load         # show all history entries starting with "load"
       history ?"set c"      # like above, several words enclosed in quotes
       hi !reread            # execute last entry starting with "reread"
       hist !"set xr"        # like above, several words enclosed in quotes
       hi !hi                # guess yourself :-))

 On systems which support a popen function (Unix), the output of history can be
 piped through an external program by starting the file name with a '|', as one
 of the above examples demonstrates.
?commands if
?if
 New syntax:
       if (<condition>) { <command>; <command>
              <commands>
              <commands>
       } else {
              <commands>
       }
 Old syntax:
       if (<condition>) <command-line> [; else if (<condition>) ...; else ...]

 This version of gnuplot supports block-structured if/else statements. If the
 keyword `if` or `else` is immediately followed by an opening "{", then 
 conditional execution applies to all statements, possibly on multiple input
 lines, until a matching "}" terminates the block.  If commands may be nested.

 The old single-line if/else syntax is still supported, but can not be
 mixed with the new block-structured syntax.  See `if-old`.
?if if-old
?if-old
 Through gnuplot version 4.4, the scope of the if/else commands was limited to
 a single input line. This has been replaced by allowing a multi-line clause to
 be enclosed in curly brackets. The old syntax is still honored by itself but
 cannot be used inside a bracketed clause.

 If no opening "{" follows the `if` keyword, the command(s) in <command-line>
 will be executed if <condition> is true (non-zero) or skipped if <condition> is
 false (zero). Either case will consume commands on the input line until the
 end of the line or an occurrence of `else`.  Note that use of `;` to allow
 multiple commands on the same line will _not_ end the conditionalized commands.

 Examples:
       pi=3
       if (pi!=acos(-1)) print "?Fixing pi!"; pi=acos(-1); print pi
 will display:
       ?Fixing pi!
       3.14159265358979
 but
       if (1==2) print "Never see this"; print "Or this either"
 will not display anything.

 else:
       v=0
       v=v+1; if (v%2) print "2" ; else if (v%3) print "3"; else print "fred"
 (repeat the last line repeatedly!)

 See `reread` for an example of using if and reread together to perform a loop.
?iteration
?iterate
 The `plot`, `splot`, `set` and `unset` commands may optionally contain an
 iteration clause.  This has the effect of executing the basic command 
 multiple times, each time re-evaluating any expressions that make use of the
 iteration control variable.  Iteration of arbitrary command sequences can be
 requested using the `do` command.
 Two forms of iteration clause are currently supported:

       for [intvar = start:end{:increment}]
       for [stringvar in "A B C D"]

 Examples:

       plot for [filename in "A.dat B.dat C.dat"] filename using 1:2 with lines
       plot for [basename in "A B C"] basename.".dat" using 1:2 with lines
       set for [i = 1:10] style line i lc rgb "blue"
       unset for [tag = 100:200] label tag

 Nested iteration is supported:

       set for [i=1:9] for [j=1:9] label i*10+j sprintf("%d",i*10+j) at i,j

 See additional documentation for `plot iteration`, `do`.

?commands load
?load
 The `load` command executes each line of the specified input file as if it
 had been typed in interactively.  Files created by the `save` command can
 later be `load`ed.  Any text file containing valid commands can be created
 and then executed by the `load` command.  Files being `load`ed may themselves
 contain `load` or `call` commands.  See `comments` for information about
 comments in commands.  To `load` with arguments, see `call`.

 Syntax:
       load "<input-file>"

 The name of the input file must be enclosed in quotes.

 The special filename "-" may be used to `load` commands from standard input.
 This allows a `gnuplot` command file to accept some commands from standard
 input.  Please see help for `batch/interactive` for more details.

 On some systems which support a popen function (Unix), the load file can be
 read from a pipe by starting the file name with a '<'.

 Examples:
       load 'work.gnu'
       load "func.dat"
       load "< loadfile_generator.sh"

 The `load` command is performed implicitly on any file names given as
 arguments to `gnuplot`.  These are loaded in the order specified, and
 then `gnuplot` exits.
?commands lower
?lower
 Syntax:
       lower {plot_window_nb}

 The `lower` command lowers (opposite to `raise`) plot window(s) associated
 with the interactive terminal of your gnuplot session, i.e. `pm`, `win`, `wxt`
 or `x11`. It puts the plot window to bottom in the z-order windows stack of
 the window manager of your desktop.

 As `x11` and `wxt` support multiple plot windows, then by default they lower
 these windows in descending order of most recently created on top to the least
 recently created on bottom. If a plot number is supplied as an optional
 parameter, only the associated plot window will be lowered if it exists.

 The optional parameter is ignored for single plot-window terminals, i.e. `pm`
 and `win`.
?commands pause
?pause
?pause mouse
 The `pause` command displays any text associated with the command and then
 waits a specified amount of time or until the carriage return is pressed.
 `pause` is especially useful in conjunction with `load` files.

 Syntax:
       pause <time> {"<string>"}
       pause mouse {<endcondition>}{, <endcondition>} {"<string>"}

 <time> may be any constant or expression.  Choosing -1 will wait until a
 carriage return is hit, zero (0) won't pause at all, and a positive number
 will wait the specified number of seconds.  The time is rounded to an integer
 number of seconds if subsecond time resolution is not supported by the given
 platform.  `pause 0` is synonymous with `print`.

 If the current terminal supports `mousing`, then `pause mouse` will terminate
 on either a mouse click or on ctrl-C.  For all other terminals, or if mousing
 is not active, `pause mouse` is equivalent to `pause -1`.

 If one or more end conditions are given after `pause mouse`, then any one of
 the conditions will terminate the pause. The possible end conditions are
 `keypress`, `button1`, `button2`, `button3`, `close`, and `any`.
 If the pause terminates on a keypress, then the ascii value of the key pressed
 is returned in MOUSE_KEY.  The character itself is returned as a one character
 string in MOUSE_CHAR. Hotkeys (bind command) are disabled if keypress is one of
 the end conditions.  Zooming is disabled if button3 is one of the end 
 conditions. 

 In all cases the coordinates of the mouse are returned in variables MOUSE_X,
 MOUSE_Y, MOUSE_X2, MOUSE_Y2.  See `mouse variables`.

 Note: Since `pause` communicates with the operating system rather than the
 graphics, it may behave differently with different device drivers (depending
 upon how text and graphics are mixed).

 Examples:
       pause -1    # Wait until a carriage return is hit
       pause 3     # Wait three seconds
       pause -1  "Hit return to continue"
       pause 10  "Isn't this pretty?  It's a cubic spline."
       pause mouse "Click any mouse button on selected data point"
       pause mouse keypress "Type a letter from A-F in the active window"
       pause mouse button1,keypress
       pause mouse any "Any key or button will terminate"

 The variant "pause mouse key" will resume after any keypress in the active
 plot window. If you want to wait for a particular key to be pressed, you can
 use a reread loop such as:

       print "I will resume after you hit the Tab key in the plot window"
       load "wait_for_tab"

 File "wait_for_tab" contains the lines

       pause mouse key
       if (MOUSE_KEY != 9) reread

?commands plot
?plot
 `plot` is the primary command for drawing plots with `gnuplot`.  It creates
 plots of functions and data in many, many ways.  `plot` is used to draw 2D
 functions and data; `splot` draws 2D projections of 3D surfaces and data.
 `plot` and `splot` offer many features in common; see `splot` for differences.
 Note specifically that although the `binary <binary list>` variation does
 work for both `plot` and `splot`, there are small differences between them.

 Syntax:
       plot {<ranges>}
            {<iteration>}
            {<function> | {"<datafile>" {datafile-modifiers}}}
            {axes <axes>} {<title-spec>} {with <style>}
            {, {definitions{,}} <function> ...}

 where either a <function> or the name of a data file enclosed in quotes is
 supplied.  A function is a mathematical expression or a pair of mathematical
 expressions in parametric mode.  Functions may be builtin, user-defined, or
 provided in the plot command itself.  Multiple datafiles and/or functions may
 be plotted in a single command, separated by commas.  See `data`, `functions`.

 Examples:
       plot sin(x)
       plot sin(x), cos(x)
       plot f(x) = sin(x*a), a = .2, f(x), a = .4, f(x)
       plot "datafile.1" with lines, "datafile.2" with points
       plot [t=1:10] [-pi:pi*2] tan(t), \
            "data.1" using (tan($2)):($3/$4) smooth csplines \
                     axes x1y2 notitle with lines 5
       plot for [datafile in "spinach.dat broccoli.dat"] datafile

 See also `show plot`.
?commands plot axes
?plot axes
?axes
 There are four possible sets of axes available; the keyword <axes> is used to
 select the axes for which a particular line should be scaled.  `x1y1` refers
 to the axes on the bottom and left; `x2y2` to those on the top and right;
 `x1y2` to those on the bottom and right; and `x2y1` to those on the top and
 left.  Ranges specified on the `plot` command apply only to the first set of
 axes (bottom left).
?binary
?data binary
?datafile binary
?plot data binary
 BINARY DATA FILES:

 Some earlier versions of `gnuplot` automatically detected binary data files.
 It is now necessary to provide the keyword `binary` after the filename.
 Adequate details of the file format must be given on the command line or
 extracted from the file itself for a supported binary `filetype`.
 In particular, there are two structures for binary files,  binary matrix
 format and binary general format.

 The `binary matrix` format contains a two dimensional array of 32 bit IEEE
 float values with an additional column and row of coordinate values.  As
 with ASCII matrix, in the `using` list, enumeration of the coordinate row
 constitutes column 1, enumeration of the coordinate column constitutes
 column 2, and the array of values constitutes column 3.

 The `binary general` format contains an arbitrary number of columns for which
 information must be specified at the command line.  For example, `array`,
 `record`, `format` and `using` can indicate the size, format and dimension
 of data.  There are a variety of useful commands for skipping file headers
 and changing endianess.  There are a set of commands for positioning and
 translating data since often coordinates are not part of the file when
 uniform sampling is inherent in the data.  Different from matrix binary or
 ASCII, general binary does not treat the generated columns as 1, 2 or 3 in
 the `using` list.  Rather, column 1 begins with column 1 of the file, or as
 specified in the `format` list.

 There are global default settings for the various binary options which may
 be set using the same syntax as the options when used as part of the `(s)plot
 <filename> binary ...` command.  This syntax is `set datafile binary ...`.
 The general rule is that common command-line specified parameters override
 file-extracted parameters which override default parameters.

 `Binary matrix` is the default binary format when no keywords specific to
 `binary general` are given, i.e., `array`, `record`, `format`, `filetype`.

 General binary data can be entered at the command line via the special file
 name '-'.  However, this is intended for use through a pipe where programs
 can exchange binary data, not for keyboards.  There is no "end of record"
 character for binary data.  Gnuplot continues reading from a pipe until it
 has read the number of points declared in the `array` qualifier.
 See `binary matrix` or `binary general` for more details.

 The `index` keyword is not supported, since the file format allows only one
 surface per file.  The `every` and `using` filters are supported.  `using`
 operates as if the data were read in the above triplet form.
 Binary File Splot Demo.
?commands plot binary general
?commands splot binary general
?plot binary general
?splot binary general
?datafile binary general
?data binary general
?binary general
 General binary data in which format information is not necessarily part of
 the file can be read by giving further details about the file format at the
 command line.  Although the syntax is slightly arcane to the casual user,
 general binary is particularly useful for application programs using gnuplot
 and sending large amounts of data.

 Syntax:
       plot '<file_name>' {binary <binary list>} ...
       splot '<file_name>' {binary <binary list>} ...

 General binary format is activated by keywords in <binary list> pertaining
 to information about file structure, i.e., `array`, `record`, `format` or
 `filetype`.  Otherwise, matrix binary format is assumed.  (See `binary matrix`
 for more details.)

 There are some standard file types that may be read for which details about
 the binary format may be extracted automatically.  (Type `show datafile
 binary` at the command line for a list.)  Otherwise, details must be
 specified at the command line or set in the defaults.  Keywords are described
 below.

 The keyword `filetype` in <binary list> controls the routine used to
 read the file, i.e., the format of the data.  For a list of the supported
 file types, type `show datafile binary filetypes`.  If no file type is
 given, the rule is that traditional gnuplot binary is assumed for `splot`
 if the `binary` keyword stands alone.  In all other circumstances, for
 `plot` or when one of the <binary list> keywords appears, a raw binary
 file is assumed whereby the keywords specify the binary format.

 General binary data files fall into two basic classes, and some files may
 be of both classes depending upon how they are treated.  There is that
 class for which uniform sampling is assumed and point coordinates must be
 generated.  This is the class for which full control via the <binary
 list> keywords applies.  For this class, the settings precedence is that
 command line parameters override in-file parameters, which override
 default settings.  The other class is that set of files for which
 coordinate information is contained within the file or there is possibly
 a non-uniform sampling such as gnuplot binary.

 Other than for the unique data files such as gnuplot binary, one should
 think of binary data as conceptually the same as ASCII data.  Each point
 has columns of information which are selected via the `<using list>`
 associated with `using`.  When no `format` string is specified, gnuplot
 will retrieve a number of binary variables equal to the largest column
 given in the `<using list>`.  For example, `using 1:3` will result in
 three columns being read, of which the second will be ignored.  There are
 default using lists based upon the typical number of parameters associated
 with a certain plot type.  For example, `with image` has a default of
 `using 1`, while `with rgbimage` has a default of `using 1:2:3`.  Note
 that the special characters for `using` representing point/line/index
 generally should not be used for binary data.  There are keywords in
 <binary list> that control this.
?binary array
 Describes the sampling array dimensions associated with the binary file.
 The coordinates will be generated by gnuplot.  A number must be specified
 for each dimension of the array.  For example, `array=(10,20)` means the
 underlying sampling structure is two-dimensional with 10 points along the
 first (x) dimension and 20 points along the second (y) dimension.
 A negative number indicates that data should be read until the end of file.
 If there is only one dimension, the parentheses may be omitted.
 A colon can be used to separate the dimensions for multiple records.
 For example, `array=25:35` indicates there are two one-dimensional records in
 the file.
       Note:  Gnuplot version 4.2 used the syntax array=128x128 rather than
              array=(128,128). The older syntax is now deprecated, but may
              still work if your copy of gnuplot was built to support
              backwards compatibility.
?binary record
 This keyword serves the same function as `array`, having the same syntax.
 However, `record` causes gnuplot to not generate coordinate information.
 This is for the case where such information may be included in one of the
 columns of the binary data file.
?binary skip
 This keyword allows you to skip sections of a binary file. For instance, if the
 file contains a 1024 byte header before the start of the data region you would
 probably want to use
       plot '<file_name>' binary skip=1024 ...
 If there are multiple records in the file, you may specify a leading offset for
 each. For example, to skip 512 bytes before the 1st record and 256 bytes before
 the second and third records
       plot '<file_name> binary record=356:356:356 skip=512:256:256 ...
?binary format
 The default binary format is a float.  For more flexibility, the format can
 include details about variable sizes.  For example, `format="%uchar%int%float"`
 associates an unsigned character with the first using column, an int with the
 second column and a float with the third column.  If the number of size
 specifications is less than the greatest column number, the size is implicitly
 taken to be similar to the last given variable size.

 Furthermore, similar to the `using` specification, the format can include
 discarded columns via the `*` character and have implicit repetition via a
 numerical repeat-field.  For example, `format="%*2int%3float"` causes gnuplot
 to discard two ints before reading three floats.  To list variable sizes, type
 `show datafile binary datasizes`.  There are a group of names that are machine
 dependent along with their sizes in bytes for the particular compilation.
 There is also a group of names which attempt to be machine independent.
?binary endian
 Often the endianess of binary data in the file does not agree with the
 endianess used by the platform on which gnuplot is running.  Several words can
 direct gnuplot how to arrange bytes.  For example `endian=little` means treat
 the binary file as having byte significance from least to greatest. The options
 are

               little:  least significant to greatest significance
                  big:  greatest significance to least significance
              default:  assume file endianess is the same as compiler
          swap (swab):  Interchange the significance.  (If things
                        don't look right, try this.)

 Gnuplot can support "middle" ("pdp") endian if it is compiled with that option.
?binary filetype
?filetype
 For some standard binary file formats gnuplot can extract all the necessary
 information from the file in question.  As an example, "format=edf" will read
 ESRF Header File format files.  For a list of the currently supported file
 formats, type `show datafile binary filetypes`.

 There is a special file type called `auto` for which gnuplot will check if the
 binary file's extension is a quasi-standard extension for a supported format.

 Command line keywords may be used to override settings extracted from the file.
 The settings from the file override any defaults.  (See `set datafile binary`
 for details.)
?binary filetype avs
?filetype avs
?avs
 `avs` is one of the automatically recognized binary file types for images.
 AVS is an extremely simple format, suitable mostly for streaming between
 applications. It consists of 2 longs (xwidth, ywidth) followed by a stream
 of pixels, each with four bytes of information alpha/red/green/blue.
?binary filetype edf
?filetype edf
?edf
?filetype ehf
?ehf
 `edf` is one of the automatically recognized binary file types for images.
 EDF stands for ESRF Data Format, and it supports both edf and ehf formats
 (the latter means ESRF Header Format).  More information on specifications
 can be found at

   http://www.edfplus.info/specs
?binary filetype png
?binary filetype gif
?binary filetype jpeg
?filetype png
?filetype gif
?filetype jpeg
 If gnuplot was configured to use the libgd library for png/gif/jpeg output, 
 then it can also be used to read these same image types as binary files.
 You can use an explicit command
       plot 'file.png' binary filetype=png
 Or the file type will be recognized automatically from the extension if you
 have previously requested
       set datafile binary filetype=auto
?binary keywords
 The following keywords apply only when generating coordinates from binary 
 data files.  That is, the control mapping the individual elements of a binary
 array, matrix, or image to specific x/y/z positions.
?binary keywords scan
 A great deal of confusion can arise concerning the relationship between how
 gnuplot scans a binary file and the dimensions seen on the plot.  To lessen
 the confusion, conceptually think of gnuplot _always_ scanning the binary file
 point/line/plane or fast/medium/slow.  Then this keyword is used to tell
 gnuplot how to map this scanning convention to the Cartesian convention shown
 in plots, i.e., x/y/z.  The qualifier for scan is a two or three letter code
 representing where point is assigned (first letter), line is assigned (second
 letter), and plane is assigned (third letter).  For example, `scan=yx` means
 the fastest, point-by-point, increment should be mapped along the Cartesian
 y dimension and the middle, line-by-line, increment should be mapped along the
 x dimension.

 When the plotting mode is `plot`, the qualifier code can include the two
 letters x and y.  For `splot`, it can include the three letters x, y and z.

 There is nothing restricting the inherent mapping from point/line/plane to
 apply only to Cartesian coordinates.  For this reason there are cylindrical
 coordinate synonyms for the qualifier codes where t (theta), r and z are
 analogous to the x, y and z of Cartesian coordinates.
?binary keywords transpose
 Shorthand notation for `scan=yx` or `scan=yxz`.
?binary keywords dx
?binary keywords dy
?dx
?dy
 When gnuplot generates coordinates, it uses the spacing described by these
 keywords.  For example `dx=10 dy=20` would mean space samples along the
 x dimension by 10 and space samples along the y dimension by 20.  `dy` cannot
 appear if `dx` does not appear.  Similarly, `dz` cannot appear if `dy` does not
 appear.  If the underlying dimensions are greater than the keywords specified,
 the spacing of the highest dimension given is extended to the other dimensions.
 For example, if an image is being read from a file and only `dx=3.5` is given
 gnuplot uses a delta x and delta y of 3.5.

 The following keywords also apply only when generating coordinates.  However
 they may also be used with matrix binary files.
?binary keywords flipx
 Sometimes the scanning directions in a binary datafile are not consistent with
 that assumed by gnuplot.  These keywords can flip the scanning direction along
 dimensions x, y, z.
?binary keywords origin
 When gnuplot generates coordinates based upon transposition and flip, it
 attempts to always position the lower left point in the array at the origin,
 i.e., the data lies in the first quadrant of a Cartesian system after transpose
 and flip.

 To position the array somewhere else on the graph, the `origin` keyword directs
 gnuplot to position the lower left point of the array at a point specified by a
 tuple.  The tuple should be a double for `plot` and a triple for `splot`.
 For example, `origin=(100,100):(100,200)` is for two records in the file and
 intended for plotting in two dimensions. A second example, `origin=(0,0,3.5)`,
 is for plotting in three dimensions.
?binary keywords center
?keywords center
 Similar to `origin`, this keyword will position the array such that its center
 lies at the point given by the tuple.  For example, `center=(0,0)`.  Center
 does not apply when the size of the array is `Inf`.
?binary keywords rotate
?keywords rotate
 The transpose and flip commands provide some flexibility in generating and
 orienting coordinates.  However, for full degrees of freedom, it is possible to
 apply a rotational vector described by a rotational angle in two dimensions.

 The `rotate` keyword applies to the two-dimensional plane, whether it be `plot`
 or `splot`.  The rotation is done with respect to the positive angle of the
 Cartesian plane.

 The angle can be expressed in radians, radians as a multiple of pi, or degrees.
 For example, `rotate=1.5708`, `rotate=0.5pi` and `rotate=90deg` are equivalent.

 If `origin` is specified, the rotation is done about the lower left sample
 point before translation.  Otherwise, the rotation is done about the array
 `center`.
?binary keywords perpendicular
 For `splot`, the concept of a rotational vector is implemented by a triple
 representing the vector to be oriented normal to the two-dimensional x-y plane.
 Naturally, the default is (0,0,1).  Thus specifying both rotate and
 perpendicular together can orient data myriad ways in three-space.

 The two-dimensional rotation is done first, followed by the three-dimensional
 rotation.  That is, if R' is the rotational 2 x 2 matrix described by an angle,
 and P is the 3 x 3 matrix projecting (0,0,1) to (xp,yp,zp), let R be
 constructed from R' at the upper left sub-matrix, 1 at element 3,3 and zeros
 elsewhere.  Then the matrix formula for translating data is v' = P R v, where v
 is the 3 x 1 vector of data extracted from the data file.  In cases where the
 data of the file is inherently not three-dimensional, logical rules are used to
 place the data in three-space.  (E.g., usually setting the z-dimension value to
 zero and placing 2D data in the x-y plane.)
?commands plot datafile
?plot datafile
?data-file
?datafile
?data
?file
 Discrete data contained in a file can be displayed by specifying the name of
 the data file (enclosed in single or double quotes) on the `plot` command line.

 Syntax:
       plot '<file_name>' {binary <binary list>}
                          {{nonuniform} matrix}
                          {index <index list> | index "<name>"}
                          {every <every list>}
                          {thru <thru expression>}
                          {using <using list>}
                          {smooth <option>}
                          {volatile} {noautoscale}

 The modifiers `binary`, `index`, `every`, `thru`, `using`, and `smooth` are
 discussed separately.  In brief, `binary` allows data entry from a binary
 file (default is ASCII), `index` selects which data sets in a multi-data-set
 file are to be plotted, `every` specifies which points within a single data
 set are to be plotted, `using` determines how the columns within a single
 record are to be interpreted (`thru` is a special case of `using`), and
 `smooth` allows for simple interpolation and approximation.  (`splot` has a
 similar syntax, but does not support the `smooth` and `thru` options.)

 The `noautoscale` keyword means that the points making up this plot will be
 ignored when automatically determining axis range limits.

 ASCII DATA FILES:

 Data files should contain at least one data point per record (`using`
 can select one data point from the record). Records beginning with `#`
 (and also with `!` on VMS) will be treated as comments and ignored.
 Each data point represents an (x,y) pair. For `plot`s with error bars or
 error bars with lines (see `set style errorbars` or `set style errorlines`),
 each data point is (x,y,ydelta), (x,y,ylow,yhigh),
 (x,y,xdelta), (x,y,xlow,xhigh), or (x,y,xlow,xhigh,ylow,yhigh).

 In all cases, the numbers of each record of a data file must be separated
 by white space (one or more blanks or tabs) unless a format specifier is
 provided by the `using` option. This white space divides each record into
 columns. However, whitespace inside a pair of double quotes is ignored when
 counting columns, so the following datafile line has three columns:
       1.0 "second column" 3.0

 Data may be written in exponential format with the exponent preceded by the
 letter e or E.  The fortran exponential specifiers d, D, q, and Q may also
 be used if the command `set datafile fortran` is in effect.

 Only one column (the y value) need be provided.  If x is omitted, `gnuplot`
 provides integer values starting at 0.

 In datafiles, blank records (records with no characters other than blanks and
 a newline and/or carriage return) are significant.

 Single blank records designate discontinuities in a `plot`; no line will join
 points separated by a blank records (if they are plotted with a line style).

 Two blank records in a row indicate a break between separate data sets.
 See `index`.

 If autoscaling has been enabled (`set autoscale`), the axes are automatically
 extended to include all datapoints, with a whole number of tic marks if tics
 are being drawn.  This has two consequences: i) For `splot`, the corner of
 the surface may not coincide with the corner of the base.  In this case, no
 vertical line is drawn.  ii) When plotting data with the same x range on a
 dual-axis graph, the x coordinates may not coincide if the x2tics are not
 being drawn.  This is because the x axis has been autoextended to a whole
 number of tics, but the x2 axis has not.  The following example illustrates
 the problem:

       reset; plot '-', '-' axes x2y1
       1 1
       19 19
       e
       1 1
       19 19
       e

 To avoid this, you can use the `fixmin`/`fixmax` feature of the
 `set autoscale` command, which turns off the automatic extension of the
 axis range up to the next tic mark.

 Label coordinates and text can also be read from a data file (see `labels`).

?commands plot datafile every
?plot datafile every
?plot every
?data-file every
?datafile every
?every
 The `every` keyword allows a periodic sampling of a data set to be plotted.

 In the discussion a "point" is a datum defined by a single record in the
 file; "block" here will mean the same thing as "datablock" (see `glossary`).

 Syntax:
       plot 'file' every {<point_incr>}
                           {:{<block_incr>}
                             {:{<start_point>}
                               {:{<start_block>}
                                 {:{<end_point>}
                                   {:<end_block>}}}}}

 The data points to be plotted are selected according to a loop from
 <`start_point`> to <`end_point`> with increment <`point_incr`> and the
 blocks according to a loop from <`start_block`> to <`end_block`> with
 increment <`block_incr`>.

 The first datum in each block is numbered '0', as is the first block in the
 file.

 Note that records containing unplottable information are counted.

 Any of the numbers can be omitted; the increments default to unity, the start
 values to the first point or block, and the end values to the last point or
 block. ':' at the end of the `every` option is not permitted.  
 If `every` is not specified, all points in all lines are plotted.

 Examples:
       every :::3::3    # selects just the fourth block ('0' is first)
       every :::::9     # selects the first 10 blocks
       every 2:2        # selects every other point in every other block
       every ::5::15    # selects points 5 through 15 in each block

 See
 simple plot demos (simple.dem)
 ,
 Non-parametric splot demos
 , and
 Parametric splot demos
 .
?commands plot datafile example
?plot datafile example
?plot example
?datafile example
?data-file example
?example
 This example plots the data in the file "population.dat" and a theoretical
 curve:

       pop(x) = 103*exp((1965-x)/10)
       set xrange [1960:1990]
       plot 'population.dat', pop(x)

 The file "population.dat" might contain:

       # Gnu population in Antarctica since 1965
          1965   103
          1970   55
          1975   34
          1980   24
          1985   10

 Binary examples:

       # Selects two float values (second one implicit) with a float value
       # discarded between them for an indefinite length of 1D data.
       plot '<file_name>' binary format="%float%*float" using 1:2 with lines

       # The data file header contains all details necessary for creating
       # coordinates from an EDF file.
       plot '<file_name>' binary filetype=edf with image
       plot '<file_name>.edf' binary filetype=auto with image

       # Selects three unsigned characters for components of a raw RGB image
       # and flips the y-dimension so that typical image orientation (start
       # at top left corner) translates to the Cartesian plane.  Pixel
       # spacing is given and there are two images in the file.  One of them
       # is translated via origin.
       plot '<file_name>' binary array=(512,1024):(1024,512) format='%uchar' \
            dx=2:1 dy=1:2 origin=(0,0):(1024,1024) flipy u 1:2:3 w rgbimage

       # Four separate records in which the coordinates are part of the
       # data file.  The file was created with a endianess different from
       # the system on which gnuplot is running.
       splot '<file_name>' binary record=30:30:29:26 endian=swap u 1:2:3

       # Same input file, but this time we skip the 1st and 3rd records
       splot '<file_name>' binary record=30:26 skip=360:348 endian=swap u 1:2:3


 See also `binary matrix`.
?commands plot datafile index
?plot datafile index
?plot index
?data-file index
?datafile index
?index
 The `index` keyword allows you to select specific data sets in a multi-data-set
 file for plotting.

 Syntax:
       plot 'file' index { <m>{:<n>{:<p>}} | "<name>" }

 Data sets are separated by pairs of blank records.  `index <m>` selects only
 set <m>; `index <m>:<n>` selects sets in the range <m> to <n>; and `index
 <m>:<n>:<p>` selects indices <m>, <m>+<p>, <m>+2<p>, etc., but stopping at
 <n>.  Following C indexing, the index 0 is assigned to the first data set in
 the file.  Specifying too large an index results in an error message.
 If <p> is specified but <n> is left blank then every <p>-th dataset is read
 until the end of the file.  If `index` is not specified, the entire file is
 plotted as a single data set.

 Example:
       plot 'file' index 4:5

 For each point in the file, the index value of the data set it appears in is
 available via the pseudo-column `column(-2)`.  This leads to an alternative way
 of distinguishing individual data sets within a file as shown below.  This is
 more awkward than the `index` command if all you are doing is selecting one
 data set for plotting, but is very useful if you want to assign different
 properties to each data set.  See `pseudocolumns`, `lc variable`.

 Example:
       plot 'file' using 1:(column(-2)==4 ? $2 : NaN)        # very awkward
       plot 'file' using 1:2:(column(-2)) linecolor variable # very useful!

 `index '<name>'` selects the data set with name '<name>'.  Names are assigned
 to data sets in comment lines.  The comment character and leading white space
 are removed from the comment line.  If the resulting line starts with <name>,
 the following data set is now named <name> and can be selected.

 Example:
       plot 'file' index 'Population'

 Please note that every comment that starts with <name> will name the following
 data set.  To avoid problems it may be useful to choose a naming scheme like
 '== Population ==' or '[Population]'.

?commands plot datafile smooth
?plot datafile smooth
?plot smooth
?data-file smooth
?datafile smooth
?smooth
 `gnuplot` includes a few general-purpose routines for interpolation and
 approximation of data; these are grouped under the `smooth` option.  More
 sophisticated data processing may be performed by preprocessing the data
 externally or by using `fit` with an appropriate model.

 Syntax:
       smooth {unique | frequency | cumulative | cnormal | kdensity 
                      | csplines | acsplines | bezier | sbezier}

 `unique`, `frequency`, `cumulative` and `cnormal` plot the data after
 making them monotonic.  Each of the other routines uses the data to
 determine the coefficients of a continuous curve between the endpoints
 of the data.  This curve is then plotted in the same manner as a
 function, that is, by finding its value at uniform intervals along the
 abscissa (see `set samples`) and connecting these points with straight
 line segments (if a line style is chosen).

 If `autoscale` is in effect, the ranges will be computed such that the
 plotted curve lies within the borders of the graph.

 If `autoscale` is not in effect, and the smooth option is either `acspline`
 or `cspline`, the sampling of the generated curve is done across the
 intersection of the x range covered by the input data and the fixed abscissa
 range as defined by `set xrange`.

 If too few points are available to allow the selected option to be applied,
 an error message is produced.  The minimum number is one for `unique` and
 `frequency`, four for `acsplines`, and three for the others.

 The `smooth` options have no effect on function plots.
?commands plot datafile smooth acsplines
?plot datafile smooth acsplines
?data-file smooth acsplines
?datafile smooth acsplines
?plot smooth acsplines
?plot acsplines
?smooth acsplines
?acsplines
 The `acsplines` option approximates the data with a "natural smoothing spline".
 After the data are made monotonic in x (see `smooth unique`), a curve is
 piecewise constructed from segments of cubic polynomials whose coefficients
 are found by the weighting the data points; the weights are taken from the
 third column in the data file.  That default can be modified by the third
 entry in the `using` list, e.g.,
       plot 'data-file' using 1:2:(1.0) smooth acsplines

 Qualitatively, the absolute magnitude of the weights determines the number
 of segments used to construct the curve.  If the weights are large, the
 effect of each datum is large and the curve approaches that produced by
 connecting consecutive points with natural cubic splines.  If the weights are
 small, the curve is composed of fewer segments and thus is smoother; the
 limiting case is the single segment produced by a weighted linear least
 squares fit to all the data.  The smoothing weight can be expressed in terms
 of errors as a statistical weight for a point divided by a "smoothing factor"
 for the curve so that (standard) errors in the file can be used as smoothing
 weights.

 Example:
       sw(x,S)=1/(x*x*S)
       plot 'data_file' using 1:2:(sw($3,100)) smooth acsplines
?commands plot datafile smooth bezier
?plot datafile smooth bezier
?plot smooth bezier
?data-file smooth bezier
?datafile smooth bezier
?plot bezier
?smooth bezier
?bezier
 The `bezier` option approximates the data with a Bezier curve of degree n
 (the number of data points) that connects the endpoints.
?commands plot datafile smooth csplines
?plot datafile smooth csplines
?plot smooth csplines
?data-file smooth csplines
?datafile smooth csplines
?plot csplines
?smooth csplines
?csplines
 The `csplines` option connects consecutive points by natural cubic splines
 after rendering the data monotonic (see `smooth unique`).
?commands plot datafile smooth sbezier
?plot datafile smooth sbezier
?plot smooth sbezier
?data-file smooth sbezier
?datafile smooth sbezier
?plot sbezier
?smooth sbezier
?sbezier
 The `sbezier` option first renders the data monotonic (`unique`) and then
 applies the `bezier` algorithm.
?commands plot datafile smooth unique
?plot datafile smooth unique
?plot smooth unique
?data-file smooth unique
?datafile smooth unique
?plot unique
?smooth unique
?unique
 The `unique` option makes the data monotonic in x; points with the same
 x-value are replaced by a single point having the average y-value.  The
 resulting points are then connected by straight line segments.
?commands plot datafile smooth frequency
?plot datafile smooth frequency
?plot smooth frequency
?data-file smooth frequency
?datafile smooth frequency
?plot frequency
?smooth frequency
?frequency
 The `frequency` option makes the data monotonic in x; points with the same
 x-value are replaced by a single point having the summed y-values.  The
 resulting points are then connected by straight line segments.
 See also
 smooth.dem
?commands plot datafile smooth cumulative
?plot datafile smooth cumulative
?plot smooth cumulative
?data-file smooth cumulative
?datafile smooth cumulative
?plot cumulative
?smooth cumulative
?cumulative
 The `cumulative` option makes the data monotonic in x; points with the same
 x-value are replaced by a single point containing the cumulative sum of 
 y-values of all data points with lower x-values (i.e. to the left of the
 current data point). This can be used to obtain a cumulative distribution 
 function from data.
 See also
 smooth.dem
?commands plot datafile smooth cnormal
?plot datafile smooth cnormal
?plot smooth cnormal
?data-file smooth cnormal
?datafile smooth cnormal
?plot cnormal
?smooth cnormal
?cnormal
 The `cnormal` option makes the data monotonic in x and normalises the
 y-values onto the range [0:1].  Points with the same x-value are
 replaced by a single point containing the cumulative sum of y-values
 of all data points with lower x-values (i.e. to the left of the
 current data point) divided by the total sum of all y-values. This can
 be used to obtain a normalised cumulative distribution function from
 data (useful when comparing sets of samples with differing numbers of
 members).
 See also
 smooth.dem

?commands plot datafile smooth kdensity
?plot datafile smooth kdensity
?plot smooth kdensity
?data-file smooth kdensity
?datafile smooth kdensity
?plot kdensity
?smooth kdensity
?kdensity
 The `kdensity` option is a way to plot a kernel density estimate (which is a
 smooth histogram) for a random collection of points, using Gaussian kernels.
 A Gaussian is placed at the location of each point in the first column and
 the sum of all these Gaussians is plotted as a function. The value in the
 second column is taken as weight of the Gaussian. (To obtain a normalized
 histogram, this should be 1/number-of-points). The value of the third column,
 if supplied, is taken as the bandwidth for the kernels. If only two columns
 have been specified, or if the value of the third column is zero or less,
 gnuplot calculates the bandwidth which would be optimal if the input data was
 normally distributed. (This will usually be a very conservative, i.e. broad 
 bandwidth.)
?commands plot datafile special-filenames
?plot datafile special-filenames
?plot special-filenames
?datafile special-filenames
?special-filenames
 There are a few filenames that have a special meaning:  '', '-', '+' and '++'.

 The empty filename '' tells gnuplot to re-use the previous input file in the
 same plot command. So to plot two columns from the same input file:

       plot 'filename' using 1:2, '' using 1:3

 The special filenames '+' and '++' are a mechanism to allow the full range of
 `using` specifiers and plot styles with in-line functions.  Normally a function
 plot can only have a single y (or z) value associated with each sampled point.
 The pseudo-file '+' treats the sampled points as column 1, and allows
 additional column values to be specified via a `using` specification, just as
 for a true input file.  The number of samples returned is controlled by
 `set samples`.
 Example:

       plot '+' using ($1):(sin($1)):(sin($1)**2) with filledcurves

 Similarly the pseudo-file '++' returns 2 columns of data forming a regular
 grid of [x,y] coordinates with the number of points along x controlled by
 `set samples` and the number of points along y controlled by `set isosamples`.
 You must set xrange and yrange before plotting '++'.
 Examples:

       splot '++' using 1:2:(sin($1)*sin($2)) with pm3d
       plot '++' using 1:2:(sin($1)*sin($2)) with image

 The special filename `'-'` specifies that the data are inline; i.e., they
 follow the command.  Only the data follow the command; `plot` options like
 filters, titles, and line styles remain on the `plot` command line.  This is
 similar to << in unix shell script, and $DECK in VMS DCL.  The data are
 entered as though they are being read from a file, one data point per record.
 The letter "e" at the start of the first column terminates data entry.  The
 `using` option can be applied to these data---using it to filter them through
 a function might make sense, but selecting columns probably doesn't!

 `'-'` is intended for situations where it is useful to have data and commands
 together, e.g., when `gnuplot` is run as a sub-process of some front-end
 application.  Some of the demos, for example, might use this feature.  While
 `plot` options such as `index` and `every` are recognized, their use forces
 you to enter data that won't be used.  For example, while

       plot '-' index 0, '-' index 1
       2
       4
       6


       10
       12
       14
       e
       2
       4
       6


       10
       12
       14
       e

 does indeed work,

       plot '-', '-'
       2
       4
       6
       e
       10
       12
       14
       e

 is a lot easier to type.

 If you use `'-'` with `replot`, you may need to enter the data more than once.
 See `replot`, `refresh`.

 A blank filename ('') specifies that the previous filename should be reused.
 This can be useful with things like

       plot 'a/very/long/filename' using 1:2, '' using 1:3, '' using 1:4

 (If you use both `'-'` and `''` on the same `plot` command, you'll need to
 have two sets of inline data, as in the example above.)

 On systems with a popen function, the datafile can be piped through a shell
 command by starting the file name with a '<'.  For example,

       pop(x) = 103*exp(-x/10)
       plot "< awk '{print $1-1965, $2}' population.dat", pop(x)

 would plot the same information as the first population example but with
 years since 1965 as the x axis.  If you want to execute this example, you
 have to delete all comments from the data file above or substitute the
 following command for the first part of the command above (the part up to
 the comma):

       plot "< awk '$0 !~ /^#/ {print $1-1965, $2}' population.dat"

 While this approach is most flexible, it is possible to achieve simple
 filtering with the `using` or `thru` keywords.

 On systems with an fdopen() function, data can be read from an arbitrary file
 descriptor attached to either a file or pipe.  To read from file descriptor
 `n` use `'<&n'`.  This allows you to easily pipe in several data files in a
 single call from a POSIX shell:

       $ gnuplot -p -e "plot '<&3', '<&4'" 3<data-3 4<data-4
       $ ./gnuplot 5< <(myprogram -with -options)
       gnuplot> plot '<&5'
?commands plot datafile thru
?plot datafile thru
?plot thru
?data-file thru
?datafile thru
?thru
 The `thru` function is provided for backward compatibility.

 Syntax:
       plot 'file' thru f(x)

 It is equivalent to:

       plot 'file' using 1:(f($2))

 While the latter appears more complex, it is much more flexible.  The more
 natural

       plot 'file' thru f(y)

 also works (i.e. you can use y as the dummy variable).

 `thru` is parsed for `splot` and `fit` but has no effect.
?commands plot datafile using
?plot datafile using
?plot using
?data-file using
?datafile using
?using
 The most common datafile modifier is `using`.  It tells the program which
 columns of data in the input file are to be plotted.

 Syntax:
       plot 'file' using <entry> {:<entry> {:<entry> ...}} {'format'}

 If a format is specified, it is used to read in each datafile record using the
 C library 'scanf' function.  Otherwise the record is interpreted as consisting
 of columns (fields) of data separated by whitespace (spaces and/or tabs),
 but see `datafile separator`.

 Each <entry> may be a simple column number that selects the value from one
 field of the input file, a string that matches a column label in the first 
 line of a data set, an expression enclosed in parentheses, or a special
 function not enclosed in parentheses such as xticlabels(2).

 If the entry is an expression in parentheses, then the function column(N) may
 be used to indicate the value in column N. That is, column(1) refers to the
 first item read, column(2) to the second, and so on.  The special symbols
 $1, $2, ... are shorthand for column(1), column(2) ...  The function `valid(N)`
 tests whether the value in the Nth column is a valid number.
 If each column of data in the input file contains a label in the first row
 rather than a data value, this label can be used to identify the column on
 input and/or in the plot legend. The column() function can be used to select
 an input column by label rather than by column number.  For example,
 if the data file contains
       Height    Weight    Age
       val1      val1      val1
       ...       ...       ...
 then the following plot commands are all equivalent
       plot 'datafile' using 3:1, '' using 3:2
       plot 'datafile' using (column("Age")):(column(1)), \
                    '' using (column("Age")):(column(2))
       plot 'datafile' using "Age":"Height", '' using "Age":"Weight"

 The full string must match. Comparison is case-sensitive.
 To use the column labels in the plot legend, use 
 `set key autotitle columnhead`.

 In addition to the actual columns 1...N in the input data file, gnuplot
 presents data from several "pseudo-columns" that hold bookkeeping information.
 E.g. $0 or column(0) returns the sequence number of this data record within a
 dataset.  Please see `pseudocolumns`.

 An empty <entry> will default to its order in the list of entries.
 For example, `using ::4` is interpreted as `using 1:2:4`.

 If the `using` list has only a single entry, that <entry> will be used for y
 and the data point number (pseudo-column $0) is used for x; for example,
 "`plot 'file' using 1`" is identical to "`plot 'file' using 0:1`".
 If the `using` list has two entries, these will be used for x and y.
 See `set style` and `fit` for details about plotting styles that make use of
 data from additional columns of input.

 'scanf' accepts several numerical specifications but `gnuplot`
 requires all inputs to be double-precision floating-point variables,
 so "%lf" is essentially the only permissible specifier.
 A format string given by the user must contain at least one such
 input specifier, and no more than seven of them.
 'scanf' expects to see white space---a blank, tab
 ("\t"), newline ("\n"), or formfeed ("\f")---between numbers; anything else
 in the input stream must be explicitly skipped.

 Note that the use of "\t", "\n", or "\f" requires use of double-quotes
 rather than single-quotes.
?examples
?commands plot datafile using examples
?plot datafile using examples
?datafile using examples
?using examples
 This creates a plot of the sum of the 2nd and 3rd data against the first:
 The format string specifies comma- rather than space-separated columns.
 The same result could be achieved by specifying `set datafile separator ","`.
       plot 'file' using 1:($2+$3) '%lf,%lf,%lf'

 In this example the data are read from the file "MyData" using a more
 complicated format:
       plot 'MyData' using "%*lf%lf%*20[^\n]%lf"

 The meaning of this format is:

       %*lf        ignore a number
       %lf         read a double-precision number (x by default)
       %*20[^\n]   ignore 20 non-newline characters
       %lf         read a double-precision number (y by default)

 One trick is to use the ternary `?:` operator to filter data:

       plot 'file' using 1:($3>10 ? $2 : 1/0)

 which plots the datum in column two against that in column one provided
 the datum in column three exceeds ten.  `1/0` is undefined; `gnuplot`
 quietly ignores undefined points, so unsuitable points are suppressed.
 Or you can use the pre-defined variable NaN to achieve the same result.

 In fact, you can use a constant expression for the column number, provided it
 doesn't start with an opening parenthesis; constructs like `using
 0+(complicated expression)` can be used.  The crucial point is that the
 expression is evaluated once if it doesn't start with a left parenthesis, or
 once for each data point read if it does.

 If timeseries data are being used, the time can span multiple columns.  The
 starting column should be specified.  Note that the spaces within the time
 must be included when calculating starting columns for other data.  E.g., if
 the first element on a line is a time with an embedded space, the y value
 should be specified as column three.

 It should be noted that `plot 'file'`, `plot 'file' using 1:2`, and `plot
 'file' using ($1):($2)` can be subtly different: 1) if `file` has some lines
 with one column and some with two, the first will invent x values when they
 are missing, the second will quietly ignore the lines with one column, and
 the third will store an undefined value for lines with one point (so that in
 a plot with lines, no line joins points across the bad point); 2) if a line
 contains text at the first column, the first will abort the plot on an error,
 but the second and third should quietly skip the garbage.

 In fact, it is often possible to plot a file with lots of lines of garbage at
 the top simply by specifying

       plot 'file' using 1:2

 However, if you want to leave text in your data files, it is safer to put the
 comment character (#) in the first column of the text lines.
?pseudocolumns
?commands plot datafile using pseudocolumns
?plot datafile using pseudocolumns
?datafile using pseudocolumns
?using pseudocolumns
 Expressions in the `using` clause of a plot statement can refer to additional
 bookkeeping values in addition to the actual data values contained in the input
 file. These are contained in "pseudocolumns".
       column(0)   The sequential order of each point within a data set.
                   The counter starts at 0 and is reset by two sequential blank
                   records.  The shorthand form $0 is available.
       column(-1)  This counter starts at 0 and is reset by a single blank line.
                   This corresponds to the data line in array or grid data.
       column(-2)  The index number of the current data set within a file that
                   contains multiple data sets.  See `index`.
?xticlabels
?using xticlabels
?plot using xticlabels
 Axis tick labels can be generated via a string function, usually taking a data
 column as an argument. The simplest form uses the data column itself as a 
 string. That is,  xticlabels(N) is shorthand for xticlabels(stringcolumn(N)).
 This example uses the contents of column 3 as x-axis tick labels.

       plot 'datafile' using <xcol>:<ycol>:xticlabels(3) with <plotstyle>

 Axis tick labels may be generated for any of the plot axes: x x2 y y2 z.
 The `ticlabels(<labelcol>)` specifiers must come after all of the data
 coordinate specifiers in the `using` portion of the command.
 For each data point which has a valid set of X,Y[,Z] coordinates,
 the string value given to xticlabels() is added to the list of xtic labels
 at the same X coordinate as the point it belongs to. `xticlabels()`
 may be shortened to `xtic()` and so on.

 Example:

       splot "data" using 2:4:6:xtic(1):ytic(3):ztic(6)

 In this example the x and y axis tic labels are taken from different columns
 than the x and y coordinate values. The z axis tics, however, are generated
 from the z coordinate of the corresponding point.

 Example:

       plot "data" using 1:2:xtic( $3 > 10. ? "A" : "B" )

 This example shows the use of a string-valued function to generate x-axis
 tick labels. Each point in the data file generates a tick mark on x labeled
 either "A" or "B" depending on the value in column 3.
?using x2ticlabels
?plot using x2ticlabels
 See `plot using xticlabels`.
?using yticlabels
?plot using yticlabels
 See `plot using xticlabels`.
?using y2ticlabels
?plot using y2ticlabels
 See `plot using xticlabels`.
?using zticlabels
?plot using zticlabels
 See `plot using xticlabels`.
?datafile volatile
?data volatile
?plot datafile volatile
?plot volatile
?volatile
 The `volatile` keyword in a plot command indicates that the data previously
 read from the input stream or file may not be available for re-reading.
 This tells the program to use `refresh` rather than `replot` commands whenever
 possible.  See `refresh`.
?commands plot errorbars
?commands splot errorbars
?plot errorbars
?splot errorbars
?errorbars
 Error bars are supported for 2D data file plots by reading one to four
 additional columns (or `using` entries); these additional values are used in
 different ways by the various errorbar styles.

 In the default situation, `gnuplot` expects to see three, four, or six
 numbers on each line of the data file---either

       (x, y, ydelta),
       (x, y, ylow, yhigh),
       (x, y, xdelta),
       (x, y, xlow, xhigh),
       (x, y, xdelta, ydelta), or
       (x, y, xlow, xhigh, ylow, yhigh).

 The x coordinate must be specified.  The order of the numbers must be
 exactly as given above, though the `using` qualifier can manipulate the order
 and provide values for missing columns.  For example,

       plot 'file' with errorbars
       plot 'file' using 1:2:(sqrt($1)) with xerrorbars
       plot 'file' using 1:2:($1-$3):($1+$3):4:5 with xyerrorbars

 The last example is for a file containing an unsupported combination of
 relative x and absolute y errors.  The `using` entry generates absolute x min
 and max from the relative error.

 The y error bar is a vertical line plotted from (x, ylow) to (x,
 yhigh). If ydelta is specified instead of ylow and yhigh, ylow = y -
 ydelta and yhigh = y + ydelta are derived. If there are only two
 numbers on the record, yhigh and ylow are both set to y. The x error
 bar is a horizontal line computed in the same fashion. To get lines
 plotted between the data points, `plot` the data file twice, once with
 errorbars and once with lines (but remember to use the `notitle`
 option on one to avoid two entries in the key). Alternately, use the
 errorlines command (see `errorlines`).

 The error bars have crossbars at each end unless `set bars` is used
 (see `set bars` for details).

 If autoscaling is on, the ranges will be adjusted to include the error bars.

 See also
 errorbar demos.

 See `plot using`, `plot with`, and `set style` for more information.
?commands plot errorlines
?commands splot errorlines
?plot errorlines
?splot errorlines
?errorlines
 Lines with error bars are supported for 2D data file plots by reading
 one to four additional columns (or `using` entries); these additional
 values are used in different ways by the various errorlines styles.

 In the default situation, `gnuplot` expects to see three, four, or six
 numbers on each line of the data file---either

       (x, y, ydelta),
       (x, y, ylow, yhigh),
       (x, y, xdelta),
       (x, y, xlow, xhigh),
       (x, y, xdelta, ydelta), or
       (x, y, xlow, xhigh, ylow, yhigh).

 The x coordinate must be specified. The order of the numbers must be
 exactly as given above, though the `using` qualifier can manipulate
 the order and provide values for missing columns. For example,

       plot 'file' with errorlines
       plot 'file' using 1:2:(sqrt($1)) with xerrorlines
       plot 'file' using 1:2:($1-$3):($1+$3):4:5 with xyerrorlines

 The last example is for a file containing an unsupported combination
 of relative x and absolute y errors. The `using` entry generates
 absolute x min and max from the relative error.

 The y error bar is a vertical line plotted from (x, ylow) to (x,
 yhigh). If ydelta is specified instead of ylow and yhigh, ylow = y -
 ydelta and yhigh = y + ydelta are derived. If there are only two
 numbers on the record, yhigh and ylow are both set to y. The x error
 bar is a horizontal line computed in the same fashion.

 The error bars have crossbars at each end unless `set bars` is used
 (see `set bars` for details).

 If autoscaling is on, the ranges will be adjusted to include the error bars.

 See `plot using`, `plot with`, and `set style` for more information.
?commands plot functions
?plot functions
?functions
 Built-in or user-defined functions can be displayed by the `plot` and `splot`
 commands in addition to, or instead of, data read from a file. The requested
 function is evaluated by sampling at regular intervals spanning the independent
 axis range[s]. See `set samples` and `set isosamples`.
 Example:
       approx(ang) = ang - ang**3 / (3*2)
       plot sin(x) title "sin(x)", approx(x) title "approximation"

 To set a default plot style for functions, see `set style function`.
 For information on built-in functions, see `expressions functions`.
 For information on defining your own functions, see `user-defined`.
?commands plot parametric
?commands splot parametric
?plot parametric
?splot parametric
 When in parametric mode (`set parametric`) mathematical expressions must be
 given in pairs for `plot` and in triplets for `splot`.

 Examples:
       plot sin(t),t**2
       splot cos(u)*cos(v),cos(u)*sin(v),sin(u)

 Data files are plotted as before, except any preceding parametric function
 must be fully specified before a data file is given as a plot.  In other
 words, the x parametric function (`sin(t)` above) and the y parametric
 function (`t**2` above) must not be interrupted with any modifiers or data
 functions; doing so will generate a syntax error stating that the parametric
 function is not fully specified.

 Other modifiers, such as `with` and `title`, may be specified only after the
 parametric function has been completed:

       plot sin(t),t**2 title 'Parametric example' with linespoints

 See also
 Parametric Mode Demos.
?commands plot ranges
?commands splot ranges
?plot ranges
?splot ranges
?ranges
 The optional axis ranges at the start of a plot command specify the region of
 the graph that will be displayed.  These override any ranges established by a
 previous `set range` statement.

 Syntax:
       [{<dummy-var>=}{{<min>}:{<max>}}]
       [{{<min>}:{<max>}}]

 The first form applies to the independent variable (`xrange` or `trange`, if
 in parametric mode).  The second form applies to the dependent variable
 `yrange` (and `xrange`, too, if in parametric mode).  <dummy-var> is a new
 name for the independent variable.  (The defaults may be changed with `set
 dummy`.)  The optional <min> and <max> terms can be constant expressions or *.

 In non-parametric mode, the order in which ranges must be given is `xrange`
 and `yrange`.

 In parametric mode, the order for the `plot` command is `trange`, `xrange`,
 and `yrange`.  The following `plot` command shows setting the `trange` to
 [-pi:pi], the `xrange` to [-1.3:1.3] and the `yrange` to [-1:1] for the
 duration of the graph:

       plot [-pi:pi] [-1.3:1.3] [-1:1] sin(t),t**2

 Note that the x2range and y2range cannot be specified here---`set x2range`
 and `set y2range` must be used.

 Ranges are interpreted in the order listed above for the appropriate mode.
 Once all those needed are specified, no further ones must be listed, but
 unneeded ones cannot be skipped---use an empty range `[]` as a placeholder.

 `*` can be used to allow autoscaling of either of min and max.  See also
 `set autoscale`.

 Ranges specified on the `plot` or `splot` command line affect only that
 graph; use the `set xrange`, `set yrange`, etc., commands to change the
 default ranges for future graphs.

 With time data, you must provide the range (in the same manner as the time
 appears in the datafile) within quotes.  `gnuplot` uses the `timefmt` string
 to read the value---see `set timefmt`.

 Examples:

 This uses the current ranges:
       plot cos(x)

 This sets the x range only:
       plot [-10:30] sin(pi*x)/(pi*x)

 This is the same, but uses t as the dummy-variable:
       plot [t = -10 :30]  sin(pi*t)/(pi*t)

 This sets both the x and y ranges:
       plot [-pi:pi] [-3:3]  tan(x), 1/x

 This sets only the y range, and turns off autoscaling on both axes:
       plot [ ] [-2:sin(5)*-8] sin(x)**besj0(x)

 This sets xmax and ymin only:
       plot [:200] [-pi:]  exp(sin(x))

 This sets the x range for a timeseries:
       set timefmt "%d/%m/%y %H:%M"
       plot ["1/6/93 12:00":"5/6/93 12:00"] 'timedata.dat'

?commands plot iteration
?commands splot iteration
?plot iteration
?splot iteration
 If many similar files or functions are to be plotted together, it may be
 convenient to do so by iterating over a shared plot command.

 Syntax:
       plot for [<variable> = <start> : <end> {:<increment>}]
       plot for [<variable> in "string of words"]

 The scope of an iteration ends at the next comma or the end of the
 command, whichever comes first.  Iteration can not be nested.

 This will plot one curve, sin(3x), because iteration ends at the comma
       plot for [i=1:3] j=i, sin(j*x)
 This will plot three curves because there is no comma after the definition of j
       plot for [i=1:3] j=i sin(j*x)

 Example:
       plot for [dataset in "apples bananas"] dataset."dat" title dataset

 In this example iteration is used both to generate a file name and a
 corresponding title.

 Example:
       file(n) = sprintf("dataset_%d.dat",n)
       splot for [i=1:10] file(i) title sprintf("dataset %d",i)

 This example defines a string-valued function that generates file names,
 and plots ten such files together. The iteration variable ('i' in this
 example) is treated as an integer, and may be used more than once.

 Example:
       set key left
       plot for [n=1:4] x**n sprintf("%d",n)

 This example plots a family of functions.

 Example:
       list = "apple banana cabbage daikon eggplant"
       item(n) = word(list,n)
       plot for [i=1:words(list)] item[i].".dat" title item(i)
       list = "new stuff"
       replot

 This example steps through a list and plots once per item.
 Because the items are retrieved dynamically, you can change the list
 and then replot.

 Example:
       list = "apple banana cabbage daikon eggplant"
       plot for [i in list] i.".dat" title i
       list = "new stuff"
       replot

 This is example does exactly the same thing as the previous example, but uses
 the string iterator form of the command rather than an integer iterator.

?commands plot title
?commands splot title
?plot title
?splot title
?columnheader
 By default each plot is listed in the key by the corresponding function or file
 name. You can give an explicit plot title instead using the `title` option.

 Syntax:
       title <text> | notitle [<ignored text>]
       title columnheader | title columnheader(N)

 where <text> is a quoted string or an expression that evaluates to a string.
 The quotes will not be shown in the key.

 There is also an option that will interpret the first entry in a column of
 input data (i.e. the column header) as a text field, and use it as the key
 title.  See `datastrings`.  This can be made the default by specifying
 `set key autotitle columnhead`.

 The line title and sample can be omitted from the key by using the keyword
 `notitle`.  A null title (`title ''`) is equivalent to `notitle`.  If only
 the sample is wanted, use one or more blanks (`title ' '`).  If `notitle`
 is followed by a string this string is ignored.

 If `key autotitles` is set (which is the default) and neither `title` nor
 `notitle` are specified the line title is the function name or the file name as
 it appears on the `plot` command.  If it is a file name, any datafile modifiers
 specified will be included in the default title.

 The layout of the key itself (position, title justification, etc.) can be
 controlled by `set key`.  Please see `set key` for details.

 Examples:

 This plots y=x with the title 'x':
       plot x

 This plots x squared with title "x^2" and file "data.1" with title
 "measured data":
       plot x**2 title "x^2", 'data.1' t "measured data"

 This puts an untitled circular border around a polar graph:
       set polar; plot my_function(t), 1 notitle

 Plot multiple columns of data, each of which contains its own title in the file
       plot for [i=1:4] 'data' using i title columnhead

?commands plot with
?commands splot with
?commands plot style
?commands splot style
?plot with
?plot style
?splot with
?splot style
?style
?with
 Functions and data may be displayed in one of a large number of styles.
 The `with` keyword provides the means of selection.

 Syntax:
       with <style> { {linestyle | ls <line_style>}
                      | {{linetype  | lt <line_type>}
                         {linewidth | lw <line_width>}
                         {linecolor | lc <colorspec>}
                         {pointtype | pt <point_type>}
                         {pointsize | ps <point_size>}
                         {fill | fs <fillstyle>}
                         {nohidden3d} {nocontours} {nosurface}
                         {palette}}
                    }


 where <style> is one of

      lines        dots       steps     errorbars     xerrorbar    xyerrorlines
      points       impulses   fsteps    errorlines    xerrorlines  yerrorbars
      linespoints  labels     histeps   financebars   xyerrorbars  yerrorlines
                                        vectors
 or
       boxes            candlesticks   image      circles
       boxerrorbars     filledcurves   rgbimage   ellipses
       boxxyerrorbars   histograms     rgbalpha   pm3d
       boxplot

 The first group of styles have associated line, point, and text properties.
 The second group of styles also have fill properties.  See `fillstyle`.  Some
 styles have further sub-styles.  See `plotting styles` for details of each.

 A default style may be chosen by `set style function` and `set style data`.

 By default, each function and data file will use a different line type and
 point type, up to the maximum number of available types.  All terminal
 drivers support at least six different point types, and re-use them, in
 order, if more are required.  To see the complete set of line and point
 types available for the current terminal, type `test`.

 If you wish to choose the line or point type for a single plot, <line_type>
 and <point_type> may be specified.  These are positive integer constants (or
 expressions) that specify the line type and point type to be used for the
 plot.  Use `test` to display the types available for your terminal.

 You may also scale the line width and point size for a plot by using
 <line_width> and <point_size>, which are specified relative to the default
 values for each terminal.  The pointsize may also be altered
 globally---see `set pointsize` for details.  But note that both <point_size>
 as set here and  as set by `set pointsize` multiply the default point
 size---their effects are  not cumulative.  That is,
 `set pointsize 2; plot x w p ps 3` will use points three times default size,
 not six.

 It is also possible to specify `pointsize variable` either as part of a
 line style or for an individual plot. In this case one extra column of input
 is required, i.e. 3 columns for a 2D plot and 4 columns for a 3D splot. The
 size of each individual point is determined by multiplying the global
 pointsize by the value read from the data file.

 If you have defined specific line type/width and point type/size combinations
 with `set style line`, one of these may be selected by setting <line_style> to
 the index of the desired style.

 If gnuplot was built with `pm3d` support, the special keyword `palette` is
 allowed for smooth color change of lines, points and dots in `splots`. The
 color is chosen from a smooth palette which was set previously with the
 command `set palette`. The color value corresponds to the z-value of the
 point coordinates or to the color coordinate if specified by the 4th parameter
 in `using`. Both 2D and 3D plots (`plot` and `splot` commands) can use palette
 colors as specified by either their fractional value or the corresponding value
 mapped to the colorbox range.  A palette color value can also be read from an
 explicitly specified input column in the `using` specifier.
 See `colors`, `set palette`, `linetype`.

 The keyword `nohidden3d` applies only to plots made with the `splot` command.
 Normally the global option `set hidden3d` applies to all plots in the graph.
 You can attach the `nohidden3d` option to any individual plots that you want
 to exclude from the hidden3d processing.  The individual elements other than
 surfaces (i.e. lines, dots, labels, ...) of a plot marked `nohidden3d` will all
 be drawn, even if they would normally be obscured by other plot elements.

 Similarly, the keyword `nocontours` will turn off contouring for an individual
 plot even if the global property `set contour` is active.

 Similarly, the keyword `nosurface` will turn off the 3D surface for an
 individual plot even if the global property `set surface` is active.

 The keywords may be abbreviated as indicated.

 Note that the `linewidth`, `pointsize` and `palette` options are not supported
 by all terminals.

 Examples:

 This plots sin(x) with impulses:
       plot sin(x) with impulses

 This plots x with points, x**2 with the default:
       plot x w points, x**2

 This plots tan(x) with the default function style, file "data.1" with lines:
       plot [ ] [-2:5] tan(x), 'data.1' with l

 This plots "leastsq.dat" with impulses:
       plot 'leastsq.dat' w i

 This plots the data file "population" with boxes:
       plot 'population' with boxes

 This plots "exper.dat" with errorbars and lines connecting the points
 (errorbars require three or four columns):
       plot 'exper.dat' w lines, 'exper.dat' notitle w errorbars

 Another way to plot "exper.dat" with errorlines (errorbars require three
 or four columns):
       plot 'exper.dat' w errorlines

 This plots sin(x) and cos(x) with linespoints, using the same line type but
 different point types:
       plot sin(x) with linesp lt 1 pt 3, cos(x) with linesp lt 1 pt 4

 This plots file "data" with points of type 3 and twice usual size:
       plot 'data' with points pointtype 3 pointsize 2

 This plots file "data" with variable pointsize read from column 4
       plot 'data' using 1:2:4 with points pt 5 pointsize variable

 This plots two data sets with lines differing only by weight:
       plot 'd1' t "good" w l lt 2 lw 3, 'd2' t "bad" w l lt 2 lw 1

 This plots filled curve of x*x and a color stripe:
       plot x*x with filledcurve closed, 40 with filledcurve y1=10

 This plots x*x and a color box:
       plot x*x, (x>=-5 && x<=5 ? 40 : 1/0) with filledcurve y1=10 lt 8

 This plots a surface with color lines:
       splot x*x-y*y with line palette

 This plots two color surfaces at different altitudes:
       splot x*x-y*y with pm3d, x*x+y*y with pm3d at t

?commands print
?print
 The `print` command prints the value of <expression> to the screen.  It is
 synonymous with `pause 0`.  <expression> may be anything that `gnuplot` can
 evaluate that produces a number, or it can be a string.

 Syntax:
       print <expression> {, <expression>, ...}

 See `expressions`.  The output file can be set with `set print`.
?commands pwd
?pwd
 The `pwd` command prints the name of the working directory to the screen.

 Note that if you wish to store the current directory into a string variable
 or use it in string expressions, then you can use variable GPVAL_PWD, see
 `show variables all`.
?commands quit
?quit
 The `exit` and `quit` commands and END-OF-FILE character will exit `gnuplot`.
 Each of these commands will clear the output device (as does the `clear`
 command) before exiting.
?commands raise
?raise
 Syntax:
       raise {plot_window_nb}

 The `raise` command raises (opposite to `lower`) plot window(s) associated
 with the interactive terminal of your gnuplot session, i.e. `pm`, `win`, `wxt`
 or `x11`. It puts the plot window to front (top) in the z-order windows stack
 of the window manager of your desktop.

 As `x11` and `wxt` support multiple plot windows, then by default they raise
 these windows in descending order of most recently created on top to the least
 recently created on bottom. If a plot number is supplied as an optional
 parameter, only the associated plot window will be raised if it exists.

 The optional parameter is ignored for single plot-windows terminal, i.e. `pm`
 and `win`.

 If the window is not raised under X11, then perhaps the plot window is
 running in a different X11 session (telnet or ssh session, for example), or
 perhaps raising is blocked by your window manager policy setting.
?commands refresh
?refresh
 The `refresh` command is similar to `replot`, with two major differences.
 `refresh` reformats and redraws the current plot using the data already read
 in. This means that you can use `refresh` for plots with in-line data
 (pseudo-device '-') and for plots from datafiles whose contents are volatile.
 You cannot use the `refresh` command to add new data to an existing plot.

 Mousing operations, in particular zoom and unzoom, will use `refresh` rather
 than `replot` if appropriate.  Example:

       plot 'datafile' volatile with lines, '-' with labels
       100 200 "Special point"
       e
       # Various mousing operations go here
       set title "Zoomed in view"
       set term post
       set output 'zoom.ps'
       refresh

?commands replot
?replot
 The `replot` command without arguments repeats the last `plot` or `splot`
 command.  This can be useful for viewing a plot with different `set` options,
 or when generating the same plot for several devices.

 Arguments specified after a `replot` command will be added onto the last
 `plot` or `splot` command (with an implied ',' separator) before it is
 repeated.  `replot` accepts the same arguments as the `plot` and `splot`
 commands except that ranges cannot be specified.  Thus you can use `replot`
 to plot a function against the second axes if the previous command was `plot`
 but not if it was `splot`.

 N.B.---use of

       plot '-' ; ... ; replot

 is not recommended, because it will require that you type in the data all
 over again.  In most cases you can use the `refresh` command instead, which
 will redraw the plot using the data previously read in.

 Note that `replot` does not work in `multiplot` mode, since it reproduces
 only the last plot rather than the entire screen.

 See also `command-line-editing` for ways to edit the last `plot` (`splot`)
 command.

 See also `show plot` to show the whole current plotting command, and the
 possibility to copy it into the `history`.
?commands reread
?reread
 The `reread` command causes the current `gnuplot` command file, as specified
 by a `load` command or on the command line, to be reset to its starting
 point before further commands are read from it.  This essentially implements
 an endless loop of the commands from the beginning of the command file to
 the `reread` command.  (But this is not necessarily a disaster---`reread` can
 be very useful when used in conjunction with `if`.)
 The `reread` command has no effect if input from standard input.

 Examples:

 Suppose the file "looper" contains the commands
       a=a+1
       plot sin(x*a)
       pause -1
       if(a<5) reread
 and from within `gnuplot` you submit the commands
       a=0
       load 'looper'
 The result will be five plots (separated by the `pause` message).

 Suppose the file "data" contains six columns of numbers with a total yrange
 from 0 to 10; the first is x and the next are five different functions of x.
 Suppose also that the file "plotter" contains the commands
       c_p = c_p+1
       plot "$0" using 1:c_p with lines linetype c_p
       if(c_p <  n_p) reread
 and from within `gnuplot` you submit the commands
       n_p=6
       c_p=1
       unset key
       set yrange [0:10]
       set multiplot
       call 'plotter' 'data'
       unset multiplot
 The result is a single graph consisting of five plots.  The yrange must be
 set explicitly to guarantee that the five separate graphs (drawn on top of
 each other in multiplot mode) will have exactly the same axes.  The linetype
 must be specified; otherwise all the plots would be drawn with the same type.
 See animate.dem in demo directory for an animated example.

?commands reset
?reset
?reset errors
?reset bind
 The `reset` command causes all graph-related options that can be set with the
 `set` command to take on their default values.  This command is useful, e.g.,
 to restore the default graph settings at the end of a command file, or to
 return to a defined state after lots of settings have been changed within a
 command file.  Please refer to the `set` command to see the default values
 that the various options take.

 The following are _not_ affected by `reset`.
      `set term` `set output` `set loadpath` `set fontpath` `set linetype`
      `set encoding` `set decimalsign` `set locale` `set psdir`

 `reset errors` clears only the error state variables GPVAL_ERRNO and
 GPVAL_ERRMSG.

 `reset bind` restores all hotkey bindings to their default state.
?commands save
?save set
?save
 The `save` command saves user-defined functions, variables, the `set
 term` status, all `set` options, or all of these, plus the last `plot`
 (`splot`) command to the specified file.

 Syntax:
       save  {<option>} '<filename>'

 where <option> is `functions`, `variables`, `terminal` or `set`. If
 no option is used, `gnuplot` saves functions, variables, `set`
 options and the last `plot` (`splot`) command.

 `save`d files are written in text format and may be read by the
 `load` command. For `save` with the `set` option or without any
 option, the `terminal` choice and the `output` filename are written
 out as a comment, to get an output file that works in other
 installations of gnuplot, without changes and without risk of
 unwillingly overwriting files.

 `save terminal` will write out just the `terminal` status, without
 the comment marker in front of it. This is mainly useful for
 switching the `terminal` setting for a short while, and getting back
 to the previously set terminal, afterwards, by loading the saved
 `terminal` status. Note that for a single gnuplot session you may
 rather use the other method of saving and restoring current terminal
 by the commands `set term push` and `set term pop`, see `set term`.

 The filename must be enclosed in quotes.

 The special filename "-" may be used to `save` commands to standard output.
 On systems which support a popen function (Unix), the output of save can be
 piped through an external program by starting the file name with a '|'.
 This provides a consistent interface to `gnuplot`'s internal settings to
 programs which communicate with `gnuplot` through a pipe.  Please see
 help for `batch/interactive` for more details.

 Examples:
       save 'work.gnu'
       save functions 'func.dat'
       save var 'var.dat'
       save set 'options.dat'
       save term 'myterm.gnu'
       save '-'
       save '|grep title >t.gp'
?commands set
?commands show
?set
?show
?show all
 The `set` command can be used to set _lots_ of options.  No screen is
 drawn, however, until a `plot`, `splot`, or `replot` command is given.

 The `show` command shows their settings;  `show all` shows all the settings.

 Options changed using `set` can be returned to the default state by giving the
 corresponding `unset` command.  See also the `reset` command, which returns
 all settable parameters to default values.

 If a variable contains time/date data, `show` will display it according to
 the format currently defined by `set timefmt`, even if that was not in effect
 when the variable was initially defined.
 The `set` and `unset` commands may optionally contain an iteration clause.
 See `iteration`.

?commands set angles
?commands show angles
?set angles
?show angles
?angles
?commands set angles degrees
?set angles degrees
?angles degrees
?degrees
 By default, `gnuplot` assumes the independent variable in polar graphs is in
 units of radians.  If `set angles degrees` is specified before `set polar`,
 then the default range is [0:360] and the independent variable has units of
 degrees.  This is particularly useful for plots of data files.  The angle
 setting also applies to 3D mapping as set via the `set mapping` command.

 Syntax:
       set angles {degrees | radians}
       show angles

 The angle specified in `set grid polar` is also read and displayed in the
 units specified by `set angles`.

 `set angles` also affects the arguments of the machine-defined functions
 sin(x), cos(x) and tan(x), and the outputs of asin(x), acos(x), atan(x),
 atan2(x), and arg(x).  It has no effect on the arguments of hyperbolic
 functions or Bessel functions.  However, the output arguments of inverse
 hyperbolic functions of complex arguments are affected; if these functions
 are used, `set angles radians` must be in effect to maintain consistency
 between input and output arguments.

       x={1.0,0.1}
       set angles radians
       y=sinh(x)
       print y         #prints {1.16933, 0.154051}
       print asinh(y)  #prints {1.0, 0.1}
 but
       set angles degrees
       y=sinh(x)
       print y         #prints {1.16933, 0.154051}
       print asinh(y)  #prints {57.29578, 5.729578}
 See also
 poldat.dem: polar plot using `set angles` demo.
?commands set arrow
?commands unset arrow
?commands show arrow
?set arrow
?unset arrow
?show arrow
?arrow
?noarrow
 Arbitrary arrows can be placed on a plot using the `set arrow` command.

 Syntax:
       set arrow {<tag>} {from <position>} {to|rto <position>}
                 { {arrowstyle | as <arrow_style>}
                   | { {nohead | head | backhead | heads}
                       {size <length>,<angle>{,<backangle>}}
                       {filled | empty | nofilled}
                       {front | back}
                       { {linestyle | ls <line_style>}
                         | {linetype | lt <line_type>}
                           {linewidth | lw <line_width} } } }

       unset arrow {<tag>}
       show arrow {<tag>}

 <tag> is an integer that identifies the arrow.  If no tag is given, the
 lowest unused tag value is assigned automatically.  The tag can be used to
 delete or change a specific arrow.  To change any attribute of an existing
 arrow, use the `set arrow` command with the appropriate tag and specify the
 parts of the arrow to be changed.

 The <position>s are specified by either x,y or x,y,z, and may be preceded by
 `first`, `second`, `graph`, `screen`, or `character` to select the coordinate
 system.  Unspecified coordinates default to 0.  The end points can be
 specified in one of five coordinate systems---`first` or `second` axes,
 `graph`, `screen`, or `character`.  See `coordinates` for details.  A
 coordinate system specifier does not carry over from the "from" position to
 the "to" position.  Arrows outside the screen boundaries are permitted but
 may cause device errors.  If the end point is specified by "rto" instead of
 "to" it is drawn relatively to the start point.  For linear axes, `graph`
 and `screen` coordinates, the distance between the start and the end point
 corresponds to the given relative coordinate.  For logarithmic axes, the
 relative given coordinate corresponds to the factor of the coordinate
 between start and end point.  Thus, a negative relative value or zero are
 not allowed for logarithmic axes.

 Specifying `nohead` produces an arrow drawn without a head---a line segment.
 This gives you yet another way to draw a line segment on the plot.  By
 default, an arrow has a head at its end. Specifying `backhead` draws an arrow
 head at the start point of the arrow while `heads` draws arrow heads on both
 ends of the line.  Not all terminal types support double-ended arrows.

 Head size can be controlled by `size <length>,<angle>` or
 `size <length>,<angle>,<backangle>`, where `<length>` defines length of each
 branch of the arrow head and `<angle>` the angle (in degrees) they make with
 the arrow.  `<Length>` is in x-axis units; this can be changed by `first`,
 `second`, `graph`, `screen`, or `character` before the <length>;  see
 `coordinates` for details.  `<Backangle>` only takes effect when `filled`
 or `empty` is also used.  Then, `<backangle>` is the angle (in degrees) the
 back branches make with the arrow (in the same direction as `<angle>`).
 The `fig` terminal has a restricted backangle function. It supports three
 different angles. There are two thresholds: Below 70 degrees, the arrow head
 gets an indented back angle. Above 110 degrees, the arrow head has an acute
 back angle. Between these thresholds, the back line is straight.

 Specifying `filled` produces filled arrow heads (if heads are used).
 Filling is supported on filled-polygon capable terminals, see help of `pm3d`
 for their list, otherwise the arrow heads are closed but not filled.
 The same result (closed but not filled arrow head) is reached by specifying
 `empty`.  Further, filling and outline is obviously not supported on
 terminals drawing arrows by their own specific routines, like `metafont`,
 `metapost`, `latex` or `tgif`.

 The line style may be selected from a user-defined list of line styles
 (see `set style line`) or may be defined here by providing values for
 <line_type> (an index from the default list of styles) and/or <line_width>
 (which is a  multiplier for the default width).

 Note, however, that if a user-defined line style has been selected, its
 properties (type and width) cannot be altered merely by issuing another
 `set arrow` command with the appropriate index and `lt` or `lw`.

 If `front` is given, the arrow is written on top of the graphed data. If
 `back` is given (the default), the arrow is written underneath the graphed
 data.  Using `front` will prevent an arrow from being obscured by dense data.

 Examples:

 To set an arrow pointing from the origin to (1,2) with user-defined style 5,
 use:
       set arrow to 1,2 ls 5

 To set an arrow from bottom left of plotting area to (-5,5,3), and tag the
 arrow number 3, use:
       set arrow 3 from graph 0,0 to -5,5,3

 To change the preceding arrow to end at 1,1,1, without an arrow head and
 double its width, use:
       set arrow 3 to 1,1,1 nohead lw 2

 To draw a vertical line from the bottom to the top of the graph at x=3, use:
       set arrow from 3, graph 0 to 3, graph 1 nohead

 To draw a vertical arrow with T-shape ends, use:
       set arrow 3 from 0,-5 to 0,5 heads size screen 0.1,90

 To draw an arrow relatively to the start point, where the relative distances
 are given in graph coordinates, use:
       set arrow from 0,-5 rto graph 0.1,0.1

 To draw an arrow with relative end point in logarithmic x axis, use:
       set logscale x
       set arrow from 100,-5 rto 10,10
 This draws an arrow from 100,-5 to 1000,5. For the logarithmic x axis, the
 relative coordinate 10 means "factor 10" while for the linear y axis, the
 relative coordinate 10 means "difference 10".

 To delete arrow number 2, use:
       unset arrow 2

 To delete all arrows, use:
       unset arrow

 To show all arrows (in tag order), use:
       show arrow

 arrows demos.

?commands set autoscale
?commands unset autoscale
?commands show autoscale
?set autoscale
?unset autoscale
?show autoscale
?autoscale
?noautoscale
 Autoscaling may be set individually on the x, y or z axis or globally on all
 axes. The default is to autoscale all axes.  If you want to autoscale based on
 a subset of the plots in the figure, you can mark the other ones with the flag
 `noautoscale`.  See `datafile`.

 Syntax:
       set autoscale {<axes>{|min|max|fixmin|fixmax|fix} | fix | keepfix}
       unset autoscale {<axes>}
       show autoscale

 where <axes> is either `x`, `y`, `z`, `cb`, `x2`, `y2` or `xy`.  A keyword with
 `min` or `max` appended (this cannot be done with `xy`) tells `gnuplot` to
 autoscale just the minimum or maximum of that axis.  If no keyword is given,
 all axes are autoscaled.

 A keyword with `fixmin`, `fixmax` or `fix` appended tells gnuplot to disable
 extension of the axis range to the next tic mark position, for autoscaled
 axes using equidistant tics; `set autoscale fix` sets this for all axes.
 Command `set autoscale keepfix` autoscales all axes while keeping the fix
 settings.

 When autoscaling, the axis range is automatically computed and the dependent
 axis (y for a `plot` and z for `splot`) is scaled to include the range of the
 function or data being plotted.

 If autoscaling of the dependent axis (y or z) is not set, the current y or z
 range is used.

 Autoscaling the independent variables (x for `plot` and x,y for `splot`) is a
 request to set the domain to match any data file being plotted.  If there are
 no data files, autoscaling an independent variable has no effect.  In other
 words, in the absence of a data file, functions alone do not affect the x
 range (or the y range if plotting z = f(x,y)).

 Please see `set xrange` for additional information about ranges.

 The behavior of autoscaling remains consistent in parametric mode, (see
 `set parametric`).  However, there are more dependent variables and hence more
 control over x, y, and z axis scales.  In parametric mode, the independent or
 dummy variable is t for `plot`s and u,v for `splot`s.  `autoscale` in
 parametric mode, then, controls all ranges (t, u, v, x, y, and z) and allows
 x, y, and z to be fully autoscaled.

 Autoscaling works the same way for polar mode as it does for parametric mode
 for `plot`, with the extension that in polar mode `set dummy` can be used to
 change the independent variable from t (see `set dummy`).

 When tics are displayed on second axes but no plot has been specified for
 those axes, x2range and y2range are inherited from xrange and yrange.  This
 is done _before_ xrange and yrange are autoextended to a whole number of
 tics, which can cause unexpected results.  You can use the `fixmin`
 or `fixmax` options to avoid this.

 Examples:

 This sets autoscaling of the y axis (other axes are not affected):
       set autoscale y

 This sets autoscaling only for the minimum of the y axis (the maximum of the
 y axis and the other axes are not affected):
       set autoscale ymin

 This disables extension of the x2 axis tics to the next tic mark,
 thus keeping the exact range as found in the plotted data and functions:
       set autoscale x2fixmin
       set autoscale x2fixmax

 This sets autoscaling of the x and y axes:
       set autoscale xy

 This sets autoscaling of the x, y, z, x2 and y2 axes:
       set autoscale

 This disables autoscaling of the x, y, z, x2 and y2 axes:
       unset autoscale

 This disables autoscaling of the z axis only:
       unset autoscale z
?commands set autoscale parametric
?set autoscale parametric
?set autoscale t
 When in parametric mode (`set parametric`), the xrange is as fully scalable
 as the y range.  In other words, in parametric mode the x axis can be
 automatically scaled to fit the range of the parametric function that is
 being plotted.  Of course, the y axis can also be automatically scaled just
 as in the non-parametric case.  If autoscaling on the x axis is not set, the
 current x range is used.

 Data files are plotted the same in parametric and non-parametric mode.
 However, there is a difference in mixed function and data plots: in
 non-parametric mode with autoscaled x, the x range of the datafile controls
 the x range of the functions; in parametric mode it has no influence.

 For completeness a last command `set autoscale t` is accepted.  However, the
 effect of this "scaling" is very minor.  When `gnuplot` determines that the
 t range would be empty, it makes a small adjustment if autoscaling is true.
 Otherwise, `gnuplot` gives an error.  Such behavior may, in fact, not be very
 useful and the command `set autoscale t` is certainly questionable.

 `splot` extends the above ideas as you would expect.  If autoscaling is set,
 then x, y, and z ranges are computed and each axis scaled to fit the
 resulting data.
?commands set autoscale polar
?set autoscale polar
 When in polar mode (`set polar`), the xrange and the yrange may be left
 in autoscale mode.  If `set rrange` is used to limit the extent of the polar
 axis, then xrange and yrange will adjust to match this automatically.
 However, explicit xrange and yrange commands can later be used to make
 further adjustments.  See `set rrange`.  The trange may also be autoscaled.
 Note that if the trange is contained within one quadrant, autoscaling will
 produce a polar plot of only that single quadrant.

 Explicitly setting one or two ranges but not others may lead to unexpected
 results.
 See also
 polar demos.
?commands set bars
?commands show bars
?set bars
?show bars
?bars
 The `set bars` command controls the tics at the ends of error bars,
 and also at the end of the whiskers belonging to a boxplot.

 Syntax:
       set bars {small | large | fullwidth | <size>} {front | back}
       unset bars
       show bars

 `small` is a synonym for 0.0, and `large` for 1.0.
 The default is 1.0 if no size is given.

 The keyword `fullwidth` is relevant only to boxplots and to histograms with
 errorbars.  It sets the width of the errorbar ends to be the same as the width
 of the associated box.  It does not change the width of the box itself.

 The `front` and `back` keywords are relevant only to errorbars attached
 to filled rectangles (boxes, candlesticks, histograms).
?commands show bind
?show bind
 Show the current state of all hotkey bindings. See `bind`.
?commands set bmargin
?set bmargin
?bmargin
 The command `set bmargin` sets the size of the bottom margin.
 Please see `set margin` for details.
?commands set border
?commands unset border
?commands show border
?set border
?unset border
?show border
?border
?noborder
 The `set border` and `unset border` commands control the display of the graph
 borders for the `plot` and `splot` commands.  Note that the borders do not
 necessarily coincide with the axes; with `plot` they often do, but with
 `splot` they usually do not.

 Syntax:
       set border {<integer>} {front | back} {linewidth | lw <line_width>}
                  {{linestyle | ls <line_style>} | {linetype | lt <line_type>}}
       unset border
       show border

 With a `splot` displayed in an arbitrary orientation, like `set view 56,103`,
 the four corners of the x-y plane can be referred to as "front", "back",
 "left" and "right".  A similar set of four corners exist for the top surface,
 of course.  Thus the border connecting, say, the back and right corners of the
 x-y plane is the "bottom right back" border, and the border connecting the top
 and bottom front corners is the "front vertical".  (This nomenclature is
 defined solely to allow the reader to figure out the table that follows.)

 The borders are encoded in a 12-bit integer: the bottom four bits control the
 border for `plot` and the sides of the base for `splot`; the next four bits
 control the verticals in `splot`; the top four bits control the edges on top
 of the `splot`.  In detail, `<integer>` should be the sum of the appropriate
 entries from the following table:

             Bit     plot        splot
               1   bottom      bottom left front
               2   left        bottom left back
               4   top         bottom right front
               8   right       bottom right back
              16   no effect   left vertical
              32   no effect   back vertical
              64   no effect   right vertical
             128   no effect   front vertical
             256   no effect   top left back
             512   no effect   top right back
            1024   no effect   top left front
            2048   no effect   top right front


 Various bits or combinations of bits may be added together in the command.

 The default is 31, which is all four sides for `plot`, and base and z axis
 for `splot`.

 In 2D plots the border is normally drawn on top of all plots elements
 (`front`). If you want the border to be drawn behind the plot elements,
 use `set border back`.

 Using the optional <line_style>, <line_type> and <line_width> specifiers, the
 way the border lines are drawn can be influenced (limited by what the current
 terminal driver supports).

 For `plot`, tics may be drawn on edges other than bottom and left by enabling
 the second axes -- see `set xtics` for details.

 If a `splot` draws only on the base, as is the case with "`unset surface; set
 contour base`", then the verticals and the top are not drawn even if they are
 specified.

 The `set grid` options 'back', 'front' and 'layerdefault' also
 control the order in which the border lines are drawn with respect to
 the output of the plotted data.

 Examples:

 Draw default borders:
       set border

 Draw only the left and bottom (`plot`) or both front and back bottom left
 (`splot`) borders:
       set border 3

 Draw a complete box around a `splot`:
       set border 4095

 Draw a topless box around a `splot`, omitting the front vertical:
       set border 127+256+512 # or set border 1023-128

 Draw only the top and right borders for a `plot` and label them as axes:
       unset xtics; unset ytics; set x2tics; set y2tics; set border 12

?commands set boxwidth
?commands show boxwidth
?set boxwidth
?show boxwidth
?boxwidth
 The `set boxwidth` command is used to set the default width of boxes in the
 `boxes`, `boxerrorbars`, `boxplot`, `candlesticks` and `histograms` styles.

 Syntax:
       set boxwidth {<width>} {absolute|relative}
       show boxwidth

 By default, adjacent boxes are extended in width until they touch each other.
 A different default width may be specified using the `set boxwidth` command.
 `Relative` widths are interpreted as being a fraction of this default width.

 An explicit value for the boxwidth is interpreted as being a number of units
 along the current x axis (`absolute`) unless the modifier `relative` is given.
 If the x axis is a log-scale (see `set log`) then the value of boxwidth is
 truly "absolute" only at x=1; this physical width is maintained everywhere
 along the axis (i.e. the boxes do not become narrower the value of x
 increases). If the range spanned by a log scale x axis is far from x=1,
 some experimentation may be required to find a useful value of boxwidth.

 The default is superseded by explicit width information taken from an extra
 data column in styles `boxes` or `boxerrorbars`.  In a four-column data set,
 the fourth column will be interpreted as the box width unless the width is set
 to -2.0, in which case the width will be calculated automatically.
 See `style boxes` and `style boxerrorbars` for more details.

 To set the box width to automatic use the command
       set boxwidth

 or, for four-column data,
       set boxwidth -2

 The same effect can be achieved with the `using` keyword in `plot`:
       plot 'file' using 1:2:3:4:(-2)

 To set the box width to half of the automatic size use
       set boxwidth 0.5 relative

 To set the box width to an absolute value of 2 use
       set boxwidth 2 absolute
?commands set clabel
?commands unset clabel
?commands show clabel
?set clabel
?unset clabel
?show clabel
?clabel
 `gnuplot` will vary the linetype used for each contour level when clabel is
 set.  When this option on (the default), a legend labels each linestyle with
 the z level it represents.  It is not possible at present to separate the
 contour labels from the surface key.

 Syntax:
       set clabel {'<format>'}
       unset clabel
       show clabel

 The default for the format string is %8.3g, which gives three decimal places.
 This may produce poor label alignment if the key is altered from its default
 configuration.

 The first contour linetype, or only contour linetype when clabel is off, is
 the surface linetype +1; contour points are the same style as surface points.

 See also `set contour`.
?commands set clip
?commands unset clip
?commands show clip
?set clip
?unset clip
?show clip
?clip
?noclip
 `gnuplot` can clip data points and lines that are near the boundaries of a
 graph.

 Syntax:
       set clip <clip-type>
       unset clip <clip-type>
       show clip

 Three clip types for points and lines are supported by `gnuplot`: `points`,
 `one`, and `two`. One, two, or all three clip types may be active for a
 single graph.
 Note that clipping of color filled quadrangles drawn by `pm3d` maps and
 surfaces is not controlled by this command, but by `set pm3d clip1in` and
 `set pm3d clip4in`.

 The `points` clip type forces `gnuplot` to clip (actually, not plot at all)
 data points that fall within but too close to the boundaries.  This is done
 so that large symbols used for points will not extend outside the boundary
 lines.  Without clipping points near the boundaries, the plot may look bad.
 Adjusting the x and y ranges may give similar results.

 Setting the `one` clip type causes `gnuplot` to draw a line segment which has
 only one of its two endpoints within the graph.  Only the in-range portion of
 the line is drawn.  The alternative is to not draw any portion of the line
 segment.

 Some lines may have both endpoints out of range, but pass through the graph.
 Setting the `two` clip-type allows the visible portion of these lines to be
 drawn.

 In no case is a line drawn outside the graph.

 The defaults are `noclip points`, `clip one`, and `noclip two`.

 To check the state of all forms of clipping, use
       show clip

 For backward compatibility with older versions, the following forms are also
 permitted:
       set clip
       unset clip

 `set clip` is synonymous with `set clip points`; `unset clip` turns off all
 three types of clipping.
?commands set cntrparam
?commands show cntrparam
?set cntrparam
?show cntrparam
?cntrparam
 `set cntrparam` controls the generation of contours and their smoothness for
 a contour plot. `show contour` displays current settings of `cntrparam` as
 well as `contour`.

 Syntax:
       set cntrparam { { linear
                       | cubicspline
                       | bspline
                       | points <n>
                       | order <n>
                       | levels { auto {<n>} | <n>
                                  | discrete <z1> {,<z2>{,<z3>...}}
                                  | incremental <start>, <incr> {,<end>}
                                }
                       }
                     }
       show contour

 This command has two functions.  First, it sets the values of z for which
 contour points are to be determined (by linear interpolation between data
 points or function isosamples.)  Second, it controls the way contours are
 drawn between the points determined to be of equal z.  <n> should be an
 integral constant expression and <z1>, <z2> ... any constant expressions.
 The parameters are:

 `linear`, `cubicspline`, `bspline`---Controls type of approximation or
 interpolation.  If `linear`, then straight line segments connect points of
 equal z magnitude.  If `cubicspline`, then piecewise-linear contours are
 interpolated between the same equal z points to form somewhat smoother
 contours, but which may undulate.  If `bspline`, a guaranteed-smoother curve
 is drawn, which only approximates the position of the points of equal-z.

 `points`---Eventually all drawings are done with piecewise-linear strokes.
 This number controls the number of line segments used to approximate the
 `bspline` or `cubicspline` curve.  Number of cubicspline or bspline
 segments (strokes) = `points` * number of linear segments.

 `order`---Order of the bspline approximation to be used.  The bigger this
 order is, the smoother the resulting contour.  (Of course, higher order
 bspline curves will move further away from the original piecewise linear
 data.)  This option is relevant for `bspline` mode only.  Allowed values are
 integers in the range from 2 (linear) to 10.

 `levels`--- Selection of contour levels,  controlled by `auto` (default),
 `discrete`, `incremental`, and <n>, number of contour levels.

 For `auto`, <n> specifies a nominal number of levels; the actual number will
 be adjusted to give simple labels. If the surface is bounded by zmin and zmax,
 contours will be generated at integer multiples of dz between zmin and zmax,
 where dz is 1, 2, or 5 times some power of ten (like the step between two
 tic marks).

 For `levels discrete`, contours will be generated at z = <z1>, <z2> ... as
 specified; the number of discrete levels sets the number of contour levels.
 In `discrete` mode, any `set cntrparam levels <n>` are ignored.

 For `incremental`, contours are generated at values of z beginning at <start>
 and increasing by <increment>, until the number of contours is reached. <end>
 is used to determine the number of contour levels, which will be changed by
 any subsequent `set cntrparam levels <n>`.  If the z axis is logarithmic,
 <increment> will be interpreted as a factor, just like in `set ztics`.

 If the command `set cntrparam` is given without any arguments specified,  the
 defaults are used: linear, 5 points, order 4, 5 auto levels.

 Examples:
       set cntrparam bspline
       set cntrparam points 7
       set cntrparam order 10

 To select levels automatically, 5 if the level increment criteria are met:
       set cntrparam levels auto 5

 To specify discrete levels at .1, .37, and .9:
       set cntrparam levels discrete .1,1/exp(1),.9

 To specify levels from 0 to 4 with increment 1:
       set cntrparam levels incremental  0,1,4

 To set the number of levels to 10 (changing an incremental end or possibly
 the number of auto levels):
       set cntrparam levels 10

 To set the start and increment while retaining the number of levels:
       set cntrparam levels incremental 100,50

 See also `set contour` for control of where the contours are drawn, and
 `set clabel` for control of the format of the contour labels and linetypes.

 See also
 contours demo (contours.dem)
 and
 contours with user defined levels demo (discrete.dem).
?commands set colorbox
?commands show colorbox
?commands unset colorbox
?set colorbox
?show colorbox
?unset colorbox
?colorbox

 The color scheme, i.e. the gradient of the smooth color with min_z and
 max_z values of `pm3d`'s `palette`, is drawn in a color box unless `unset
 colorbox`.

       set colorbox
       set colorbox {
                  { vertical | horizontal }
                  { default | user }
                  { origin x, y }
                  { size x, y }
                  { front | back }
                  { noborder | bdefault | border [line style] }
                }
       show colorbox
       unset colorbox

 Color box position can be `default` or `user`.  If the latter is specified the
 values as given with the `origin` and `size` subcommands are used. The box
 can be drawn after (`front`) or before (`back`) the graph or the surface.

 The orientation of the color gradient can be switched by options `vertical`
 and `horizontal`.

 `origin x, y` and `size x, y` are used only in combination with the `user`
 option. The x and y values are interpreted as screen coordinates by default,
 and this is the only legal option for 3D plots. 2D plots, including splot with
 `set view map`, allow any coordinate system to be specified.  Try for example:
     set colorbox horiz user origin .1,.02 size .8,.04
 which will draw a horizontal gradient somewhere at the bottom of the graph.

 `border` turns the border on (this is the default). `noborder` turns the border
 off. If an positive integer argument is given after `border`, it is used as a
 line style tag which is used for drawing the border, e.g.:
     set style line 2604 linetype -1 linewidth .4
     set colorbox border 2604
 will use line style `2604`, a thin line with the default border color (-1)
 for drawing the border. `bdefault` (which is the default) will use the default
 border line style for drawing the border of the color box.

 The axis of the color box is called `cb` and it is controlled by means of the
 usual axes commands, i.e. `set/unset/show` with `cbrange`, `[m]cbtics`,
 `format cb`, `grid [m]cb`, `cblabel`, and perhaps even `cbdata`, `[no]cbdtics`,
 `[no]cbmtics`.

 `set colorbox` without any parameter switches the position to default.
 `unset colorbox` resets the default parameters for the colorbox and switches
 the colorbox off.

 See also help for `set pm3d`, `set palette`, `x11 pm3d`, and `set style line`.
?colornames
?show colornames
?commands show colornames
?show palette colornames
 Gnuplot knows a limited number of color names. You can use these to define
 the color range spanned by a pm3d palette, or to assign a terminal-independent
 color to a particular linetype or linestyle. To see the list of known color
 names, use the command `show colornames`.   Example:

       set style line 1 linecolor rgb "sea-green"
?commands set contour
?commands unset contour
?commands show contour
?set contour
?unset contour
?show contour
?contour
?nocontour
 `set contour` enables contour drawing for surfaces.  This option is available
 for `splot` only.  It requires grid data, see `grid_data` for more details.
 If contours are desired from non-grid data, `set dgrid3d` can be used to
 create an appropriate grid.

 Syntax:
       set contour {base | surface | both}
       unset contour
       show contour

 The three options specify where to draw the contours: `base` draws the
 contours on the grid base where the x/ytics are placed, `surface` draws the
 contours on the surfaces themselves, and `both` draws the contours on both
 the base and the surface.  If no option is provided, the default is `base`.

 See also `set cntrparam` for the parameters that affect the drawing of
 contours, and `set clabel` for control of labelling of the contours.

 The surface can be switched off (see `set surface`), giving a contour-only
 graph.  Though it is possible to use `set size` to enlarge the plot to fill
 the screen, more control over the output format can be obtained by writing
 the contour information to a file, and rereading it as a 2D datafile plot:

       unset surface
       set contour
       set cntrparam ...
       set table 'filename'
       splot ...
       unset table
       # contour info now in filename
       set term <whatever>
       plot 'filename'

 In order to draw contours, the data should be organized as "grid data".  In
 such a file all the points for a single y-isoline are listed, then all the
 points for the next y-isoline, and so on.  A single blank line (a line
 containing no characters other than blank spaces and a carriage return and/or
 a line feed) separates one y-isoline from the next.
 See also `splot datafile`.

 See also
 contours demo (contours.dem)
 and
 contours with user defined levels demo (discrete.dem).
?set data style
 This form of the command is deprecated. Please see `set style data`.
?set datafile
?show datafile
 The `set datafile` command options control interpretation of fields read from
 input data files by the `plot`, `splot`, and `fit` commands.  Six such
 options are currently implemented.
?set datafile fortran
?show datafile fortran
?fortran
 The `set datafile fortran` command enables a special check for values in the
 input file expressed as Fortran D or Q constants. This extra check slows down
 the input process, and should only be selected if you do in fact have datafiles
 containing Fortran D or Q constants. The option can be disabled again using
 `unset datafile fortran`.
?set datafile nofpe_trap
?fpe_trap
?nofpe_trap
 The `set datafile nofpe_trap` command tells gnuplot not to re-initialize a
 floating point exception handler before every expression evaluation used while
 reading data from an input file.  This can significantly speed data input from
 very large files at the risk of program termination if a floating-point
 exception is generated.
?set datafile missing
?show datafile missing
?set missing
?missing
 The `set datafile missing` command allows you to tell `gnuplot` what character
 string is used in a data file to denote missing data.  Exactly how this missing
 value will be treated depends on the `using` specifier of the `plot` or `splot`
 command.

 Syntax:
       set datafile missing {"<string>"}
       show datafile missing
       unset datafile

 Example:
       # Ignore entries containing IEEE NaN ("Not a Number") code
       set datafile missing "NaN"

 Example:
       set style data linespoints
       plot '-'
          1 10
          2 20
          3 ?
          4 40
          5 50
          e
       set datafile missing "?"
       plot '-'
          1 10
          2 20
          3 ?
          4 40
          5 50
          e
       plot '-' using 1:2
          1 10
          2 20
          3 ?
          4 40
          5 50
          e
       plot '-' using 1:($2)
          1 10
          2 20
          3 ?
          4 40
          5 50
          e

 The first `plot` will recognize only the first datum in the "3 ?" line.  It
 will use the single-datum-on-a-line convention that the line number is "x"
 and the datum is "y", so the point will be plotted (in this case erroneously)
 at (2,3).

 The second and third `plot` commands will correctly ignore the middle line.
 The plotted line will connect the points at (2,20) and (4,40).

 The fourth `plot` will also correctly ignore the middle line, but the plotted
 line will not connect the points at (2,20) and (4,40).

 There is no default character for `missing`, but in many cases any
 non-parsible string of characters found where a numerical value is expected
 will be treated as missing data.

?set datafile separator
?show datafile separator
?datafile separator
?separator
 The command `set datafile separator "<char>"` tells `gnuplot` that data fields
 in subsequent input files are separated by <char> rather than by whitespace.
 The most common use is to read in csv (comma-separated value) files written
 by spreadsheet or database programs. By default data fields are separated by
 whitespace.

 Syntax:
       set datafile separator {"<char>" | whitespace}

 Examples:
       # Input file contains tab-separated fields
       set datafile separator "\t"

       # Input file contains comma-separated values fields
       set datafile separator ","
?set datafile commentschars
?commentschars
 The `set datafile commentschars` command allows you to tell `gnuplot` what
 characters are used in a data file to denote comments.  Gnuplot will ignore
 rest of the line behind the specified characters if either of them is the
 first non-blank character on the line.

 Syntax:
       set datafile commentschars {"<string>"}
       show datafile commentschars
       unset commentschars

 Default value of the string is "#!" on VMS and "#" otherwise.

 Then, the following line in a data file is completely ignored
     # 1 2 3 4
 but the following
     1 # 3 4
 produces rather unexpected plot unless
     set datafile missing '#'
 is specified as well.

 Example:
       set datafile commentschars "#!%"
?set datafile binary
 The `set datafile binary` command is used to set the defaults when reading
 binary data files.  The syntax matches precisely that used for commands
 `plot` and `splot`.  See `binary matrix` and `binary general` for details
 about the keywords that can be present in <binary list>.

 Syntax:
       set datafile binary <binary list>
       show datafile binary
       show datafile
       unset datafile

 Examples:
       set datafile binary filetype=auto
       set datafile binary array=(512,512) format="%uchar"

?show datafile binary
       show datafile binary   # list current settings
?commands set decimalsign
?commands show decimalsign
?commands unset decimalsign
?set decimalsign
?show decimalsign
?unset decimalsign
?decimalsign
 The `set decimalsign` command selects a decimal sign for numbers printed
 into tic labels or `set label` strings.

 Syntax:
       set decimalsign {<value> | locale {"<locale>"}}
       unset decimalsign
       show decimalsign

 The argument <value> is a string to be used in place of the usual
 decimal point. Typical choices include the period, '.', and the comma,
 ',', but others may be useful, too.  If you omit the <value> argument,
 the decimal separator is not modified from the usual default, which is
 a period.  Unsetting decimalsign has the same effect as omitting <value>.

 Example:

 Correct typesetting in most European countries requires:
       set decimalsign ','

 Please note: If you set an explicit string, this affects only numbers that
 are printed using gnuplot's gprintf() formatting routine, include axis tics.
 It does not affect the format expected for input data, and it does not affect
 numbers printed with the sprintf() formatting routine. To change the behavior
 of both input and output formatting, instead use the form

       set decimalsign locale

 This instructs the program to use both input and output formats in accordance
 with the current setting of the LC_ALL, LC_NUMERIC, or LANG environmental
 variables.

       set decimalsign locale "foo"

 This instructs the program to format all input and output in accordance with
 locale "foo", which must be installed.  If locale "foo" is not found then an
 error message is printed and the decimal sign setting is unchanged.
 On linux systems you can get a list of the locales installed on your machine by
 typing "locale -a". A typical linux locale string is of the form "sl_SI.UTF-8".
 A typical Windows locale string is of the form "Slovenian_Slovenia.1250" or
 "slovenian". Please note that interpretation of the locale settings is done by
 the C library at runtime. Older C libraries may offer only partial support for
 locale settings such as the thousands grouping separator character.

       set decimalsign locale; set decimalsign "."

 This sets all input and output to use whatever decimal sign is correct for
 the current locale, but over-rides this with an explicit '.' in numbers
 formatted using gnuplot's internal gprintf() function.
?commands set dgrid3d
?commands unset dgrid3d
?commands show dgrid3d
?set dgrid3d
?unset dgrid3d
?show dgrid3d
?dgrid3d
?nodgrid3d
?kdensity2d
 The `set dgrid3d` command enables, and can set parameters for, non-grid to
 grid data mapping.  See `splot grid_data` for more details about the grid data
 structure.

 Syntax:
       set dgrid3d {<rows>} {,{<cols>}}
                   { splines |
                     qnorm {<norm>} |
                     (gauss | cauchy | exp | box | hann) 
                       {kdensity} {<dx>} {,<dy>} }
       unset dgrid3d
       show dgrid3d

 By default `dgrid3d` is disabled.  When enabled, 3D data read from a file
 are always treated as a scattered data set.  A grid with dimensions derived
 from a bounding box of the scattered data and size as specified by the
 row/col_size parameters is created for plotting and contouring.  The grid
 is equally spaced in x (rows) and in y (columns); the z values are computed
 as weighted averages or spline interpolations of the scattered points' z 
 values. In other words, a regularly spaced grid is created and the a smooth
 approximation to the raw data is evaluated for all grid points. This
 approximation is plotted in place of the raw data.

 The number of columns defaults to the number of rows, which defaults to 10.

 Several algorithms are available to calculate the approximation from the
 raw data. Some of these algorithms can take additional parameters.
 These interpolations are such the closer the data point is to a grid point, 
 the more effect it has on that grid point.

 The `splines` algorithm calculates an interpolation based on "thin plate
 splines". It does not take additional parameters.

 The `qnorm` algorithm calculates a weighted average of the input data at
 each grid point. Each data point is weighted inversely by its distance from
 the grid point raised to the norm power.  (Actually, the weights are given
 by the inverse of dx^norm + dy^norm, where dx and dy are the components of
 the separation of the grid point from each data point.  For some norms 
 that are powers of two, specifically 4, 8, and 16, the computation is 
 optimized by using the Euclidean distance in the weight calculation, 
 (dx^2+dy^2)^norm/2.  However, any non-negative integer can be used.) 
 The power of the norm can be specified as a single optional parameter. 
 This algorithm is the default.

 Finally, several smoothing kernels are available to calculate weighted
 averages: z = Sum_i w(d_i) * z_i / Sum_i w(d_i), where z_i is the value
 of the i-th data point and d_i is the distance between the current grid
 point and the location of the i-th data point. All kernels assign higher
 weights to data points that are close to the current grid point and lower
 weights to data points further away.

 The following kernels are available:
       gauss :     w(d) = exp(-d*d)
       cauchy :    w(d) = 1/(1 + d*d)
       exp :       w(d) = exp(-d)
       box :       w(d) = 1                     if d<1
                        = 0                     otherwise
       hann :      w(d) = 0.5*(1-cos(2*pi*d))   if d<1
                   w(d) = 0                     otherwise

 When using one of these five smoothing kernels, up to two additional
 numerical parameters can be specified: dx and dy. These are used to 
 rescale the coordinate differences when calculating the distance: 
 d_i = sqrt( ((x-x_i)/dx)**2 + ((y-y_i)/dy)**2 ), where x,y are the
 coordinates of the current grid point and x_i,y_i are the coordinates
 of the i-th data point. The value of dy defaults to the value of dx,
 which defaults to 1. The parameters dx and dy make it possible to 
 control the radius over which data points contribute to a grid point
 IN THE UNITS OF THE DATA ITSELF.

 The optional keyword `kdensity2d`, which must come after the name of the
 kernel, but before the (optional) scale parameters, modifies the algorithm
 so that the values calculated for the grid points are not divided by the 
 sum of the weights ( z = Sum_i w(d_i) * z_i ). If all z_i are constant, 
 this effectively plots a bivariate kernel density estimate: a kernel 
 function (one of the five defined above) is placed at each data point,
 the sum of these kernels is evaluated at every grid point, and this smooth
 surface is plotted instead of the original data. This is similar in 
 principle to + what the `smooth kdensity` option does to 1D datasets.
 (See kdensity2d.dem for usage demo)

 A slightly different syntax is also supported for reasons of backwards
 compatibility. If no interpolation algorithm has been explicitly selected,
 the `qnorm` algorithm is assumed. Up to three comma-separated, optional
 parameters can be specified, which are interpreted as the the number of
 rows, the number of columns, and the norm value, respectively.

 The `dgrid3d` option is a simple scheme which replaces scattered data
 with weighted averages on a regular grid.  More sophisticated approaches
 to this problem exist and should be used to preprocess the data outside
 `gnuplot` if this simple solution is found inadequate.

 See also
 dgrid3d.dem: dgrid3d demo.
 and
 scatter.dem: dgrid3d demo.

?commands set dummy
?commands show dummy
?set dummy
?show dummy
?dummy
 The `set dummy` command changes the default dummy variable names.

 Syntax:
       set dummy {<dummy-var>} {,<dummy-var>}
       show dummy

 By default, `gnuplot` assumes that the independent, or "dummy", variable for
 the `plot` command is "t" if in parametric or polar mode, or "x" otherwise.
 Similarly the independent variables for the `splot` command are "u" and "v"
 in parametric mode (`splot` cannot be used in polar mode), or "x" and "y"
 otherwise.

 It may be more convenient to call a dummy variable by a more physically
 meaningful or conventional name.  For example, when plotting time functions:

       set dummy t
       plot sin(t), cos(t)

 At least one dummy variable must be set on the command; `set dummy` by itself
 will generate an error message.

 Examples:
       set dummy u,v
       set dummy ,s

 The second example sets the second variable to s.
?commands set encoding
?commands show encoding
?set encoding
?show encoding
?encoding
?encodings
 The `set encoding` command selects a character encoding.
 Syntax:
       set encoding {<value>}
       set encoding locale
       show encoding

 Valid values are
    default     - tells a terminal to use its default encoding
    iso_8859_1  - the most common Western European encoding used by many
                  Unix workstations and by MS-Windows. This encoding is
                  known in the PostScript world as 'ISO-Latin1'.
    iso_8859_15 - a variant of iso_8859_1 that includes the Euro symbol
    iso_8859_2  - used in Central and Eastern Europe
    iso_8859_9  - used in Turkey (also known as Latin5)
    koi8r       - popular Unix cyrillic encoding
    koi8u       - ukrainian Unix cyrillic encoding
    cp437       - codepage for MS-DOS
    cp850       - codepage for OS/2, Western Europe
    cp852       - codepage for OS/2, Central and Eastern Europe
    cp950       - MS version of Big5 (emf terminal only)
    cp1250      - codepage for MS Windows, Central and Eastern Europe
    cp1251      - codepage for 8-bit Russian, Serbian, Bulgarian, Macedonian
    cp1254      - codepage for MS Windows, Turkish (superset of Latin5)
    sjis        - shift-JIS Japanese encoding
    utf8        - variable-length (multibyte) representation of Unicode
                  entry point for each character

 The command `set encoding locale` is different from the other options.
 It attempts to determine the current locale from the runtime environment.
 On most systems this is controlled by the environmental variables
 LC_ALL, LC_CTYPE, or LANG.  This mechanism is necessary, for example, to
 pass multibyte character encodings such as UTF-8 or EUC_JP to the wxt
 and cairopdf terminals.  This command does not affect the locale-specific
 representation of dates or numbers.
 See also `set locale` and `set decimalsign`.

 Generally you must set the encoding before setting the terminal type.
 Note that encoding is not supported by all terminal drivers and that
 the device must be able to produce the desired non-standard characters.
?commands set fit
?commands show fit
?set fit
?show fit
 The `fit` setting defines where the `fit` command writes its output.

 Syntax:
       set fit {logfile {"<filename>"}} {{no}errorvariables} {{no}quiet}
       unset fit
       show fit

 The <filename> argument must be enclosed in single or double quotes.

 If no filename is given or `unset fit` is used the log file is
 reset to its default value "fit.log" or the value of the environmental
 variable `FIT_LOG`.

 If the given logfile name ends with a / or \, it is interpreted to be
 a directory name, and the actual filename will be "fit.log" in that
 directory.

 If the `errorvariables` option is turned on, the error of each fitted
 parameter computed by `fit` will be copied to a user-defined variable
 whose name is formed by appending "_err" to the name of the parameter
 itself.  This is useful mainly to put the parameter and its error onto
 a plot of the data and the fitted function, for reference, as in:

        set fit errorvariables
        fit f(x) 'datafile' using 1:2 via a, b
        print "error of a is:", a_err
        set label 'a=%6.2f', a, '+/- %6.2f', a_err
        plot 'datafile' using 1:2, f(x)

 By default the information written to the log file is also echoed to
 the terminal session. `set fit quiet` turns off the echo.
?commands set fontpath
?commands show fontpath
?set fontpath
?show fontpath
?fontpath
 The `fontpath` setting defines additional locations for font files
 searched when including font files. Currently only the postscript terminal
 supports `fontpath`. If a file cannot be found in the current directory,
 the directories in `fontpath` are tried. Further documentation concerning
 the supported file formats is included in the `terminal postscript` section
 of the documentation.

 Syntax:
       set fontpath {"pathlist1" {"pathlist2"...}}
       show fontpath

 Path names may be entered as single directory names, or as a list of
 path names separated by a platform-specific path separator, eg. colon
 (':') on Unix, semicolon (';') on DOS/Windows/OS/2 platforms.
 The `show fontpath`, `save` and `save set` commands replace the
 platform-specific separator with a space character (' ') for maximum
 portability. If a directory name ends with an exclamation mark ('!') also
 the subdirectories of this directory are searched for font files.

 If the environmental variable GNUPLOT_FONTPATH is set, its contents are
 appended to `fontpath`.  If it is not set, a system dependent default value
 is used. It is set by testing several directories for existence when using
 the fontpath the first time. Thus, the first call of `set fontpath`,
 `show fontpath`, `save fontpath`, `plot`, or `splot` with embedded font
 files takes a little more time. If you want to save this time you may
 set the environmental variable GNUPLOT_FONTPATH since probing is switched
 off, then. You can find out which is the default fontpath by using
 `show fontpath`.

 `show fontpath` prints the contents of the user-defined fontpath and the
 system fontpath separately.  However, the `save` and `save set` commands
 save only the user-specified parts of `fontpath`.

 For terminal drivers that access fonts by filename via the gd library, the
 font search path is controlled by the environmental variable GDFONTPATH.
?commands set format
?commands show format
?set format
?show format
?format
?format cb
 The format of the tic-mark labels can be set with the `set format` command
 or with the `set tics format` or individual `set {axis}tics format` commands.

 Syntax:
       set format {<axes>} {"<format-string>"}
       set format {<axes>} {'<format-string>'}
       show format

 where <axes> is either `x`, `y`, `xy`, `x2`, `y2`, `z`, `cb` or nothing
 (which applies the format to all axes). The following two commands are
 equivalent:
       set format y "%.2f"
       set ytics format "%.2f"

 The length of the string is restricted to 100 characters.  The default format
 is "% g", but other formats such as "%.2f" or "%3.0em" are often desirable.
 The format "$%g$" is often desirable for LaTeX.  If no format string is given,
 the format will be returned to the default.  If the empty string "" is given,
 tics will have no labels, although the tic mark will still be plotted.
 To eliminate the tic marks, use `unset xtics` or `set tics scale 0`.

 Newline (\n) and enhanced text markup is accepted in the format string.
 Use double-quotes rather than single-quotes in this case.  See also `syntax`.
 Characters not preceded by "%" are printed verbatim.  Thus you can include
 spaces and labels in your format string, such as "%g m", which will put " m"
 after each number.  If you want "%" itself, double it: "%g %%".

 See also `set xtics` for more information about tic labels, and
 `set decimalsign` for how to use non-default decimal separators in numbers
 printed this way.
 See also
 electron demo (electron.dem).
?gprintf
 The string function gprintf("format",x) uses gnuplot's own format specifiers,
 as do the gnuplot commands `set format`, `set timestamp`, and others. These
 format specifiers are not the same as those used by the standard C-language
 routine sprintf(). gprintf() accepts only a single variable to be formatted.
 Gnuplot also provides an sprintf("format",x1,x2,...) routine if you prefer.
 For a list of gnuplot's format options, see `format specifiers`.
?commands set format specifiers
?set format specifiers
?format specifiers
?format_specifiers
 The acceptable formats (if not in time/date mode) are:

       Format       Explanation
       %f           floating point notation
       %e or %E     exponential notation; an "e" or "E" before the power
       %g or %G     the shorter of %e (or %E) and %f
       %x or %X     hex
       %o or %O     octal
       %t           mantissa to base 10
       %l           mantissa to base of current logscale
       %s           mantissa to base of current logscale; scientific power
       %T           power to base 10
       %L           power to base of current logscale
       %S           scientific power
       %c           character replacement for scientific power
       %b           mantissa of ISO/IEC 80000 notation (ki, Mi, Gi, Ti, Pi, Ei, Zi, Yi) 
       %B           prefix of ISO/IEC 80000 notation (ki, Mi, Gi, Ti, Pi, Ei, Zi, Yi) 
       %P           multiple of pi


 A 'scientific' power is one such that the exponent is a multiple of three.
 Character replacement of scientific powers (`"%c"`) has been implemented
 for powers in the range -18 to +18.  For numbers outside of this range the
 format reverts to exponential.

 Other acceptable modifiers (which come after the "%" but before the format
 specifier) are "-", which left-justifies the number; "+", which forces all
 numbers to be explicitly signed; " " (a space), which makes positive numbers
 have a space in front of them where negative numbers have "-";
 "#", which places a decimal point after
 floats that have only zeroes following the decimal point; a positive integer,
 which defines the field width; "0" (the digit, not the letter) immediately
 preceding the field width, which indicates that leading zeroes are to be used
 instead of leading blanks; and a decimal point followed by a non-negative
 integer, which defines the precision (the minimum number of digits of an
 integer, or the number of digits following the decimal point of a float).

 Some systems may not support all of these modifiers but may also support
 others; in case of doubt, check the appropriate documentation and
 then experiment.

 Examples:
       set format y "%t"; set ytics (5,10)          # "5.0" and "1.0"
       set format y "%s"; set ytics (500,1000)      # "500" and "1.0"
       set format y "%+-12.3f"; set ytics(12345)    # "+12345.000  "
       set format y "%.2t*10^%+03T"; set ytic(12345)# "1.23*10^+04"
       set format y "%s*10^{%S}"; set ytic(12345)   # "12.345*10^{3}"
       set format y "%s %cg"; set ytic(12345)       # "12.345 kg"
       set format y "%.0P pi"; set ytic(6.283185)   # "2 pi"
       set format y "%.0f%%"; set ytic(50)          # "50%"

       set log y 2; set format y '%l'; set ytics (1,2,3)
       #displays "1.0", "1.0" and "1.5" (since 3 is 1.5 * 2^1)

 There are some problem cases that arise when numbers like 9.999 are printed
 with a format that requires both rounding and a power.

 If the data type for the axis is time/date, the format string must contain
 valid codes for the 'strftime' function (outside of `gnuplot`, type "man
 strftime").  See `set timefmt` for a list of the allowed input format codes.
?commands set format date_specifiers
?commands set format time_specifiers
?set format date_specifiers
?set format time_specifiers
?set date_specifiers
?set time_specifiers
?date_specifiers
?time_specifiers
 In time/date mode, the acceptable formats are:

       Format       Explanation
       %a           abbreviated name of day of the week
       %A           full name of day of the week
       %b or %h     abbreviated name of the month
       %B           full name of the month
       %d           day of the month, 01--31
       %D           shorthand for "%m/%d/%y" (only output)
       %F           shorthand for "%Y-%m-%d" (only output)
       %k           hour, 0--23 (one or two digits)
       %H           hour, 00--23 (always two digits)
       %l           hour, 1--12 (one or two digits)
       %I           hour, 01--12 (always two digits)
       %j           day of the year, 1--366
       %m           month, 01--12
       %M           minute, 0--60
       %p           "am" or "pm"
       %r           shorthand for "%I:%M:%S %p" (only output)
       %R           shorthand for "%H:%M" (only output)
       %s           number of seconds since the start of year 2000
       %S           second, integer 0--60 on output, (double) on input
       %T           shorthand for "%H:%M:%S" (only output)
       %U           week of the year (week starts on Sunday)
       %w           day of the week, 0--6 (Sunday = 0)
       %W           week of the year (week starts on Monday)
       %y           year, 0-68 for 2000-2068, 69-99 for 1969-1999
       %Y           year, 4-digit



 Except for the non-numerical formats, these may be preceded by a "0" ("zero",
 not "oh") to pad the field length with leading zeroes, and a positive digit,
 to define the minimum field width (which will be overridden if the specified
 width is not large enough to contain the number).  The %S format also accepts
 a precision specifier so that fractional seconds can be written.
 There is a 24-character limit to the length of the printed text;
 longer strings will be truncated.

 Examples:

 Suppose the text is "76/12/25 23:11:11".  Then
       set format x                 # defaults to "12/25/76" \n "23:11"
       set format x "%A, %d %b %Y"  # "Saturday, 25 Dec 1976"
       set format x "%r %D"         # "11:11:11 pm 12/25/76"

 Suppose the text is "98/07/06 05:04:03.123456".  Then
       set format x "%1y/%2m/%3d %01H:%02M:%06.3S"  # "98/ 7/  6 5:04:03.123"
?set function style
 This form of the command is deprecated. Please see `set style function`.
?commands show functions
?show functions
 The `show functions` command lists all user-defined functions and their
 definitions.

 Syntax:
       show functions

 For information about the definition and usage of functions in `gnuplot`,
 please see `expressions`.
 See also
 splines as user defined functions (spline.dem)
 and
 use of functions and complex variables for airfoils (airfoil.dem).
?commands set grid
?commands unset grid
?commands show grid
?set grid
?unset grid
?show grid
?grid
?nogrid
 The `set grid` command allows grid lines to be drawn on the plot.

 Syntax:
       set grid {{no}{m}xtics} {{no}{m}ytics} {{no}{m}ztics}
                {{no}{m}x2tics} {{no}{m}y2tics}
                {{no}{m}cbtics}
                {polar {<angle>}}
                {layerdefault | front | back}
                { {linestyle <major_linestyle>}
                  | {linetype | lt <major_linetype>}
                    {linewidth | lw <major_linewidth>}
                  { , {linestyle | ls <minor_linestyle>}
                      | {linetype | lt <minor_linetype>}
                        {linewidth | lw <minor_linewidth>} } }
       unset grid
       show grid

 The grid can be enabled and disabled for the major and/or minor tic
 marks on any axis, and the linetype and linewidth can be specified
 for major and minor grid lines, also via a predefined linestyle, as
 far as the active terminal driver supports this.

 Additionally, a polar grid can be selected for 2D plots---circles are drawn
 to intersect the selected tics, and radial lines are drawn at definable
 intervals.  (The interval is given in degrees or radians, depending on the
 `set angles` setting.)  Note that a polar grid is no longer automatically
 generated in polar mode.

 The pertinent tics must be enabled before `set grid` can draw them; `gnuplot`
 will quietly ignore instructions to draw grid lines at non-existent tics, but
 they will appear if the tics are subsequently enabled.

 If no linetype is specified for the minor gridlines, the same linetype as the
 major gridlines is used.  The default polar angle is 30 degrees.

 If `front` is given, the grid is drawn on top of the graphed data. If
 `back` is given, the grid is drawn underneath the graphed data. Using
 `front` will prevent the grid from being obscured by dense data. The
 default setup, `layerdefault`, is equivalent to `back` for 2D plots.
 In 3D plots the default is to split up the grid and the graph box into
 two layers: one behind, the other in front of the plotted data and
 functions. Since `hidden3d` mode does its own sorting, it ignores
 all grid drawing order options and passes the grid lines through the
 hidden line removal machinery instead. These options actually affect
 not only the grid, but also the lines output by `set border` and the
 various ticmarks (see `set xtics`).

 Z grid lines are drawn on the bottom of the plot.  This looks better if a
 partial box is drawn around the plot---see `set border`.
?commands set hidden3d
?commands unset hidden3d
?commands show hidden3d
?set hidden3d
?unset hidden3d
?show hidden3d
?hidden3d
?nohidden3d
 The `set hidden3d` command enables hidden line removal for surface plotting
 (see `splot`).  Some optional features of the underlying algorithm can also
 be controlled using this command.

 Syntax:
       set hidden3d {defaults} |
                    { {front|back}
                      {{offset <offset>} | {nooffset}}
                      {trianglepattern <bitpattern>}
                      {{undefined <level>} | {noundefined}}
                      {{no}altdiagonal}
                      {{no}bentover} }
       unset hidden3d
       show hidden3d

 In contrast to the usual display in gnuplot, hidden line removal actually
 treats the given function or data grids as real surfaces that can't be seen
 through, so plot elements behind the surface will be hidden by it.  For this
 to work, the surface needs to have 'grid structure' (see `splot datafile`
 about this), and it has to be drawn `with lines` or `with linespoints`.

 When `hidden3d` is set, both the hidden portion of the surface and possibly
 its contours drawn on the base (see `set contour`) as well as the grid will
 be hidden.  Each surface has its hidden parts removed with respect to itself
 and to other surfaces, if more than one surface is plotted.  Contours drawn
 on the surface (`set contour surface`) don't work.

 Labels and arrows are always visible and are unaffected.  The key box is never
 hidden by the surface. As of gnuplot version 4.6, hidden3d also affects 3D
 plotting styles `points`, `labels`, `vectors`, and `impulses` even if no
 surface is present in the graph.  Individual plots within the graph may be
 explicitly excluded from this processing by appending the extra option 
 `nohidden3d` to the `with` specifier.

 Hidden3d does not affect solid surfaces drawn using the pm3d mode. To achieve
 a similar effect purely for pm3d surfaces, use instead `set pm3d depthorder`.
 To mix pm3d surfaces with normal `hidden3d` processing, use the option
 `set hidden3d front` to force all elements included in hidden3d processing to
 be drawn after any remaining plot elements. Then draw the surface twice, once
 `with lines lt -2` and a second time `with pm3d`. The first instance will
 include the surface during calculation of occluded elements but will not draw
 the surface itself.

 Functions are evaluated at isoline intersections.  The algorithm interpolates
 linearly between function points or data points when determining the visible
 line segments.  This means that the appearance of a function may be different
 when plotted with `hidden3d` than when plotted with `nohidden3d` because in
 the latter case functions are evaluated at each sample.  Please see
 `set samples` and `set isosamples` for discussion of the difference.

 The algorithm used to remove the hidden parts of the surfaces has some
 additional features controllable by this command.  Specifying `defaults` will
 set them all to their default settings, as detailed below.  If `defaults` is
 not given, only explicitly specified options will be influenced: all others
 will keep their previous values, so you can turn on/off hidden line removal
 via `set {no}hidden3d`, without modifying the set of options you chose.

 The first option, `offset`, influences the linetype used for lines on the
 'back' side.  Normally, they are drawn in a linetype one index number higher
 than the one used for the front, to make the two sides of the surface
 distinguishable.  You can specify a different linetype offset to add
 instead of the default 1, by `offset <offset>`.  Option `nooffset` stands for
 `offset 0`, making the two sides of the surface use the same linetype.

 Next comes the option `trianglepattern <bitpattern>`.  <bitpattern> must be
 a number between 0 and 7, interpreted as a bit pattern.  Each bit determines
 the visibility of one edge of the triangles each surface is split up into.
 Bit 0 is for the 'horizontal' edges of the grid, Bit 1 for the 'vertical'
 ones, and Bit 2 for the diagonals that split each cell of the original grid
 into two triangles.  The default pattern is 3, making all horizontal and
 vertical lines visible, but not the diagonals.  You may want to choose 7 to
 see those diagonals as well.

 The `undefined <level>` option lets you decide what the algorithm is to do
 with data points that are undefined (missing data, or undefined function
 values), or exceed the given x-, y- or z-ranges.  Such points can either be
 plotted nevertheless, or taken out of the input data set.  All surface
 elements touching a point that is taken out will be taken out as well, thus
 creating a hole in the surface.  If <level> = 3, equivalent to option
 `noundefined`, no points will be thrown away at all.  This may produce all
 kinds of problems elsewhere, so you should avoid this.  <level> = 2 will
 throw away undefined points, but keep the out-of-range ones.  <level> = 1,
 the default, will get rid of out-of-range points as well.

 By specifying `noaltdiagonal`, you can override the default handling of a
 special case can occur if `undefined` is active (i.e. <level> is not 3).
 Each cell of the grid-structured input surface will be divided in two
 triangles along one of its diagonals.  Normally, all these diagonals have
 the same orientation relative to the grid.  If exactly one of the four cell
 corners is excluded by the `undefined` handler, and this is on the usual
 diagonal, both triangles will be excluded.  However if the default setting
 of `altdiagonal` is active, the other diagonal will be chosen for this cell
 instead, minimizing the size of the hole in the surface.

 The `bentover` option controls what happens to another special case, this
 time in conjunction with the `trianglepattern`.  For rather crumply surfaces,
 it can happen that the two triangles a surface cell is divided into are seen
 from opposite sides (i.e. the original quadrangle is 'bent over'), as
 illustrated in the following ASCII art:

                                                               C----B
     original quadrangle:  A--B      displayed quadrangle:     |\   |
       ("set view 0,0")    | /|    ("set view 75,75" perhaps)  | \  |
                           |/ |                                |  \ |
                           C--D                                |   \|
                                                               A    D

 If the diagonal edges of the surface cells aren't generally made visible by
 bit 2 of the <bitpattern> there, the edge CB above wouldn't be drawn at all,
 normally, making the resulting display hard to understand.  Therefore, the
 default option of `bentover` will turn it visible in this case.  If you don't
 want that, you may choose `nobentover` instead.
 See also
 hidden line removal demo (hidden.dem)
 and
 complex hidden line demo (singulr.dem).
?commands set historysize
?set historysize
?unset historysize
?historysize
?nohistorysize
 Note: the command `set historysize` is only available when
 gnuplot has been configured to use the GNU readline library.

 Syntax:
       set historysize <int>
       unset historysize

 When leaving gnuplot, the value of historysize is used for
 truncating the history to at most that much lines. The default
 is 500.
 `unset historysize` will disable history truncation and thus
 allow an infinite number of lines to be written to the history
 file.
?commands set isosamples
?commands show isosamples
?set isosamples
?show isosamples
?isosamples
 The isoline density (grid) for plotting functions as surfaces may be changed
 by the `set isosamples` command.

 Syntax:
       set isosamples <iso_1> {,<iso_2>}
       show isosamples

 Each function surface plot will have <iso_1> iso-u lines and <iso_2> iso-v
 lines.  If you only specify <iso_1>, <iso_2> will be set to the same value
 as <iso_1>.  By default, sampling is set to 10 isolines per u or v axis.
 A higher sampling rate will produce more accurate plots, but will take longer.
 These parameters have no effect on data file plotting.

 An isoline is a curve parameterized by one of the surface parameters while
 the other surface parameter is fixed.  Isolines provide a simple means to
 display a surface.  By fixing the u parameter of surface s(u,v), the iso-u
 lines of the form c(v) = s(u0,v) are produced, and by fixing the v parameter,
 the iso-v lines of the form c(u) = s(u,v0) are produced.

 When a function surface plot is being done without the removal of hidden
 lines, `set samples`  controls the number of points sampled along each
 isoline;  see `set samples` and `set hidden3d`. The contour algorithm
 assumes that a function sample occurs at each isoline intersection, so
 change in `samples` as well as `isosamples` may be desired when changing
 the resolution of a function surface/contour.
?commands set key
?commands unset key
?commands show key
?set key
?unset key
?show key
?key
?nokey
?legend
 The `set key` command enables a key (or legend) describing plots on a plot.

 The contents of the key, i.e., the names given to each plotted data set and
 function and samples of the lines and/or symbols used to represent them, are
 determined by the `title` and `with` options of the {`s`}`plot` command.
 Please see `plot title` and `plot with` for more information.

 Syntax:
       set key {on|off} {default}
               {{inside | outside} | {lmargin | rmargin | tmargin | bmargin}
                 | {at <position>}}
               {left | right | center} {top | bottom | center}
               {vertical | horizontal} {Left | Right}
               {{no}opaque}
               {{no}reverse} {{no}invert}
               {samplen <sample_length>} {spacing <vertical_spacing>}
               {width <width_increment>}
               {height <height_increment>}
               {{no}autotitle {columnheader}}
               {title "<text>"} {{no}enhanced}
               {font "<face>,<size>"} {textcolor <colorspec>}
               {{no}box { {linestyle | ls <line_style>}
                          | {linetype | lt <line_type>}
                            {linewidth | lw <line_width>}}}
               {maxcols {<max no. of columns> | auto}}
               {maxrows {<max no. of rows> | auto}}
       unset key
       show key

 The key contains a title and a sample (line, point, box) for each plot
 in the graph. The key may be turned off by requesting `set key off` or
 `unset key`.  Individual key entries may be turned off by using the
 `notitle` keyword in the corresponding plot command.

 Elements within the key are stacked according to `vertical` or `horizontal`.
 In the case of `vertical`, the key occupies as few columns as possible.  That
 is, elements are aligned in a column until running out of vertical space at
 which point a new column is started.  The vertical space may be limited using
 'maxrows'.  In the case of `horizontal`, the key occupies as few rows as
 possible.  The horizontal space may be limited using 'maxcols'.

 By default the key is placed in the upper right inside corner of the graph.
 The keywords `left`, `right`, `top`, `bottom`, `center`, `inside`, `outside`,
 `lmargin`, `rmargin`, `tmargin`, `bmargin` (, `above`, `over`, `below` and
 `under`) may be used to automatically place the key in other positions of the
 graph.  Also an `at <position>` may be given to indicate precisely where the
 plot should be placed.  In this case, the keywords `left`, `right`, `top`,
 `bottom` and `center` serve an analogous purpose for alignment.
 For more information, see `key placement`.

 Justification of the plot titles within the key is controlled by `Left` or
 `Right` (default).  The text and sample can be reversed (`reverse`) and a
 box can be drawn around the key (`box {...}`) in a specified `linetype`
 and `linewidth`, or a user-defined `linestyle`.

 By default the key is built up one plot at a time. That is, the key symbol and
 title are drawn at the same time as the corresponding plot.  That means newer
 plots may sometimes place elements on top of the key.  `set key opaque` causes
 the key to be generated after all the plots.  In this case the key area is 
 filled with background color and then the key symbols and titles are written.
 Therefore the key itself may obscure portions of some plot elements.
 The default can be restored by `set key noopaque`.

 By default the first plot label is at the top of the key and successive labels
 are entered below it. The `invert` option causes the first label to be placed
 at the bottom of the key, with successive labels entered above it. This option
 is useful to force the vertical ordering of labels in the key to match the
 order of box types in a stacked histogram.

 The <height_increment> is a number of character heights to be added to or
 subtracted from the height of the key box.  This is useful mainly when you are
 putting a box around the key and want larger borders around the key entries.

 All plotted curves of `plot`s and `splot`s are titled according to the
 default option `autotitles`. The automatic generation of titles can be
 suppressed by `noautotitles`; then only those titles explicitly defined
 by `(s)plot ... title ...` will be drawn.

 The command `set key autotitle columnheader` causes the first entry in each
 column of input data to be interpreted as a text string and used as a title for
 the corresponding plot. If the quantity being plotted is a function of data
 from several columns, gnuplot may be confused as to which column to draw the
 title from. In this case it is necessary to specify the column explicitly in
 the plot command, e.g.

       plot "datafile" using (($2+$3)/$4) title columnhead(3) with lines

 An overall title can be put on the key (`title "<text>"`)---see also `syntax`
 for the distinction between text in single- or double-quotes.  The key title
 uses the same justification as do the plot titles.

 The defaults for `set key` are `on`, `right`, `top`, `vertical`, `Right`,
 `noreverse`, `noinvert`, `samplen 4`, `spacing 1.25`, `title ""`, and
 `nobox`.  The default <linetype> is the same as that used for the plot
 borders.  Entering `set key default` returns the key to its default
 configuration.

 The key is drawn as a sequence of lines, with one plot described on each
 line.  On the right-hand side (or the left-hand side, if `reverse` is
 selected) of each line is a representation that attempts to mimic the way the
 curve is plotted.  On the other side of each line is the text description
 (the line title), obtained from the `plot` command.  The lines are vertically
 arranged so that an imaginary straight line divides the left- and right-hand
 sides of the key.  It is the coordinates of the top of this line that are
 specified with the `set key` command.  In a `plot`, only the x and y
 coordinates are used to specify the line position.  For a `splot`, x, y and
 z are all used as a 3D location mapped using the same mapping as the graph
 itself to form the required 2D screen position of the imaginary line.

 When using the TeX or other terminals where formatting information is embedded
 in the string, `gnuplot` can only estimate the correctly exact width of the
 string for key positioning.  If the key is to be positioned at the left, it may
 be convenient to use the combination  `set key left Left reverse`.

 If `splot` is being used to draw contours, the contour labels will be listed
 in the key.  If the alignment of these labels is poor or a different number
 of decimal places is desired, the label format can be specified.  See
 `set clabel` for details.

 Examples:

 This places the key at the default location:
       set key default

 This disables the key:
       unset key

 This places a key at coordinates 2,3.5,2 in the default (first) coordinate
 system:
       set key at 2,3.5,2

 This places the key below the graph:
       set key below

 This places the key in the bottom left corner, left-justifies the text,
 gives it a title, and draws a box around it in linetype 3:
       set key left bottom Left title 'Legend' box 3
?commands set key placement
?set key placement
?key placement
 To understand positioning, the best concept is to think of a region, i.e.,
 inside/outside, or one of the margins.  Along with the region, keywords
 `left/center/right` (l/c/r) and `top/center/bottom` (t/c/b) control where
 within the particular region the key should be placed.

 When in `inside` mode, the keywords `left` (l), `right` (r), `top` (t),
 `bottom` (b), and `center` (c) push the key out toward the plot boundary as
 illustrated:

      t/l   t/c   t/r

      c/l    c    c/r

      b/l   b/c   b/r


 When in `outside` mode, automatic placement is similar to the above
 illustration, but with respect to the view, rather than the graph boundary.
 That is, a border is moved inward to make room for the key outside of
 the plotting area, although this may interfere with other labels and may
 cause an error on some devices.  The particular plot border that is moved
 depends upon the position described above and the stacking direction.  For
 options centered in one of the dimensions, there is no ambiguity about which
 border to move.  For the corners, when the stack direction is `vertical`, the
 left or right border is moved inward appropriately.  When the stack direction
 is `horizontal`, the top or bottom border is moved inward appropriately.

 The margin syntax allows automatic placement of key regardless of stack
 direction.  When one of the margins `lmargin` (lm), `rmargin` (rm),
 `tmargin` (tm), and `bmargin` (bm) is combined with a single, non-conflicting
 direction keyword, the following illustrated positions may contain the key:

           l/tm  c/tm  r/tm

      t/lm                  t/rm

      c/lm                  c/rm

      b/lm                  b/rm

           l/bm  c/bm  r/bm


 Keywords `above` and `over` are synonymous with `tmargin`.  For version
 compatibility, `above` or `over` without an additional l/c/r or stack direction
 keyword uses `center` and `horizontal`.  Keywords `below` and `under` are
 synonymous with `bmargin`.  For compatibility, `below` or `under` without an
 additional l/c/r or stack  direction keyword uses `center` and `horizontal`.  A
 further compatibility issue is that `outside` appearing without an additional
 t/b/c or stack direction keyword uses `top`, `right` and `vertical` (i.e., the
 same as t/rm above).

 The <position> can be a simple x,y,z as in previous versions, but these can
 be preceded by one of five keywords (`first`, `second`, `graph`, `screen`,
 `character`) which selects the coordinate system in which the position of
 the first sample line is specified.  See `coordinates` for more details.
 The effect of `left`, `right`, `top`, `bottom`, and `center` when <position>
 is given is to align the key as though it were text positioned using the
 label command, i.e., `left` means left align with key to the right of
 <position>, etc.
?commands set key samples
?set key samples
?key samples
 By default, each plot on the graph generates a corresponding entry in the key.
 This entry contains a plot title and a sample line/point/box of the same color
 and fill properties as used in the plot itself.  The font and textcolor
 properties control the appearance of the individual plot titles that appear in
 the key. Setting the textcolor to "variable" causes the text for each key
 entry to be the same color as the line or fill color for that plot.
 This was the default in some earlier versions of gnuplot.

 The length of the sample line can be controlled by `samplen`.  The sample
 length is computed as the sum of the tic length and <sample_length> times the
 character width.  `samplen` also affects the positions of point samples in
 the key since these are drawn at the midpoint of the sample line, even if
 the sample line itself is not drawn.

 The vertical spacing between lines is controlled by `spacing`.  The spacing
 is set equal to the product of the pointsize, the vertical tic size, and
 <vertical_spacing>.  The program will guarantee that the vertical spacing is
 no smaller than the character height.

 The <width_increment> is a number of character widths to be added to or
 subtracted from the length of the string.  This is useful only when you are
 putting a box around the key and you are using control characters in the text.
 `gnuplot` simply counts the number of characters in the string when computing
 the box width; this allows you to correct it.
?commands set label
?commands unset label
?commands show label
?set label
?unset label
?show label
?label
?nolabel
 Arbitrary labels can be placed on the plot using the `set label` command.

 Syntax:
       set label {<tag>} {"<label text>"} {at <position>}
                 {left | center | right}
                 {norotate | rotate {by <degrees>}}
                 {font "<name>{,<size>}"}
                 {noenhanced}
                 {front | back}
                 {textcolor <colorspec>}
                 {point <pointstyle> | nopoint}
                 {offset <offset>}
       unset label {<tag>}
       show label

 The <position> is specified by either x,y or x,y,z, and may be preceded by
 `first`, `second`, `graph`, `screen`, or `character` to select the coordinate
 system.  See `coordinates` for details.

 The tag is an integer that is used to identify the label. If no <tag>
 is given, the lowest unused tag value is assigned automatically.  The
 tag can be used to delete or modify a specific label.  To change any
 attribute of an existing label, use the `set label` command with the
 appropriate tag, and specify the parts of the label to be changed.

 The <label text> can be a string constant, a string variable, or a string-
 valued expression. See `strings`, `sprintf`, and `gprintf`.

 By default, the text is placed flush left against the point x,y,z.  To adjust
 the way the label is positioned with respect to the point x,y,z, add the
 justification parameter, which may be `left`, `right` or `center`,
 indicating that the point is to be at the left, right or center of the text.
 Labels outside the plotted boundaries are permitted but may interfere with
 axis labels or other text.

 If `rotate` is given, the label is written vertically (if the terminal can do
 so, of course).  If `rotate by <degrees>` is given, conforming terminals will
 try to write the text at the specified angle; non-conforming terminals will
 treat this as vertical text.

 Font and its size can be chosen explicitly by `font "<name>{,<size>}"` if the
 terminal supports font settings.  Otherwise the default font of the terminal
 will be used.

 Normally the enhanced text mode string interpretation, if enabled for the
 current terminal, is applied to all text strings including label text.
 The `noenhanced` property can be used to exempt a specific label from the
 enhanced text mode processing.  The can be useful if the label contains
 underscores, for example. See `enhanced text`.

 If `front` is given, the label is written on top of the graphed data. If
 `back` is given (the default), the label is written underneath the graphed
 data.  Using `front` will prevent a label from being obscured by dense data.

 `textcolor <colorspec>` changes the color of the label text. <colorspec> can be
 a linetype, an rgb color, or a palette mapping. See help for `colorspec` and
 `palette`.  `textcolor` may be abbreviated `tc`.
    `tc default` resets the text color to its default state.
    `tc lt <n>` sets the text color to that of line type <n>.
    `tc ls <n>` sets the text color to that of line style <n>.
    `tc palette z` selects a palette color corresponding to the label z position.
    `tc palette cb <val>` selects a color corresponding to <val> on the colorbar.
    `tc palette fraction <val>`, with 0<=val<=1, selects a color corresponding to
        the mapping [0:1] to grays/colors of the `palette`.
    `tc rgb "#RRGGBB"` selects an arbitrary 24-bit RGB color.

 If a <pointstyle> is given, using keywords `lt`, `pt` and `ps`, see `style`,
 a point with the given style and color of the given line type is plotted at
 the label position and the text of the label is displaced slightly.
 This option is used by default for placing labels in `mouse` enhanced
 terminals.  Use `nopoint` to turn off the drawing of a point near
 the label (this is the default).

 The displacement defaults to 1,1 in `pointsize` units if a <pointstyle> is
 given, 0,0 if no <pointstyle> is given.  The displacement can be controlled
 by the optional `offset <offset>` where <offset> is specified by either x,y
 or x,y,z, and may be preceded by `first`, `second`, `graph`, `screen`, or
 `character` to select the coordinate system.  See `coordinates` for details.

 If one (or more) axis is timeseries, the appropriate coordinate should be
 given as a quoted time string according to the `timefmt` format string.
 See `set xdata` and `set timefmt`.

 The EEPIC, Imagen, LaTeX, and TPIC drivers allow \\ in a string to specify
 a newline.

 Label coordinates and text can also be read from a data file (see `labels`).

 Examples:

 To set a label at (1,2) to "y=x", use:
       set label "y=x" at 1,2

 To set a Sigma of size 24, from the Symbol font set, at the center of
 the graph, use:
       set label "S" at graph 0.5,0.5 center font "Symbol,24"

 To set a label "y=x^2" with the right of the text at (2,3,4), and tag the
 label as number 3, use:
       set label 3 "y=x^2" at 2,3,4 right

 To change the preceding label to center justification, use:
       set label 3 center

 To delete label number 2, use:
       unset label 2

 To delete all labels, use:
       unset label

 To show all labels (in tag order), use:
       show label

 To set a label on a graph with a timeseries on the x axis, use, for example:
       set timefmt "%d/%m/%y,%H:%M"
       set label "Harvest" at "25/8/93",1

 To display a freshly fitted parameter on the plot with the data and the
 fitted function, do this after the `fit`, but before the `plot`:
       set label sprintf("a = %3.5g",par_a) at 30,15
       bfit = gprintf("b = %s*10^%S",par_b)
       set label bfit at 30,20

 To display a function definition along with its fitted parameters, use:
       f(x)=a+b*x
       fit f(x) 'datafile' via a,b
       set label GPFUN_f at graph .05,.95
       set label sprintf("a = %g", a) at graph .05,.90 
       set label sprintf("b = %g", b) at graph .05,.85

 To set a label displaced a little bit from a small point:
       set label 'origin' at 0,0 point lt 1 pt 2 ps 3 offset 1,-1

 To set a label whose color matches the z value (in this case 5.5) of some
 point on a 3D splot colored using pm3d:
       set label 'text' at 0,0,5.5 tc palette z
?commands set linetype
?commands unset linetype
?commands show linetype
?set linetype
?unset linetype
?show linetype
?linetype
 The `set linetype` command allows you to redefine the basic linetypes used
 for plots.  The command options are identical to those for "set style line".
 Unlike line styles, redefinitions by `set linetype` are persistent;  they
 are not affected by `reset`.

 For example, linetypes one and two default to red and green. If you redefine
 them like this:

       set linetype 1 lw 2 lc rgb "blue" pointtype 6
       set linetype 2 lw 2 lc rgb "forest-green" pointtype 8

 everywhere that uses lt 1 will now get a thick blue line rather than a thin red
 line (the previous default meaning of lt 1).  This includes uses such as the
 definition of a temporary linestyle derived from the base linetype 1.

 `Note`: This command is new to gnuplot version 4.6.  It supersedes a rather
 cryptic command in version 4.2 "set style increment user".
 The older command is now deprecated.

 This mechanism can be used to define a set of personal preferences for the
 sequence of lines used in gnuplot.  The recommended way to do this is to add
 to the run-time initialization file ~/.gnuplot a sequence of commands like

       if ((GPVAL_VERSION < 4.5) \
       ||  (!strstrt(GPVAL_COMPILE_OPTIONS,"+USER_LINETYPES"))) \
           exit
       set linetype 1 lc rgb "dark-violet" lw 2 pt 0
       set linetype 2 lc rgb "sea-green"   lw 2 pt 7
       set linetype 3 lc rgb "cyan"        lw 2 pt 6 pi -1
       set linetype 4 lc rgb "dark-red"    lw 2 pt 5 pi -1
       set linetype 5 lc rgb "blue"        lw 2 pt 8
       set linetype 6 lc rgb "dark-orange" lw 2 pt 3
       set linetype 7 lc rgb "black"       lw 2 pt 11
       set linetype 8 lc rgb "goldenrod"   lw 2
       set linetype cycle 8

 Every time you run gnuplot the line types will be initialized to these values.
 You may initialize as many linetypes as you like. If you do not redefine, say,
 linetype 3 then it will continue to have the default properties (in this case
 blue, pt 3, lw 1, etc).  The first few lines of the example script insure that
 the commands will be skipped by older versions of gnuplot.

 Similar script files can be used to define theme-based color choices, or sets
 of colors optimized for a particular plot type or output device.

 The command `set linetype cycle 8` tells gnuplot to re-use these definitions
 for the color and linewidth of higher-numbered linetypes.  That is, linetypes
 9-16, 17-24, and so on will use this same sequence of colors and widths.
 The point properties (pointtype, pointsize, pointinterval) are not affected by
 this command.  `unset linetype cycle` disables this feature.  If the line
 properties of a higher numbered linetype are explicitly defined, this takes
 precedence over the recycled low-number linetype properties.

?commands set lmargin
?set lmargin
?lmargin
 The command `set lmargin` sets the size of the left margin.
 Please see `set margin` for details.
?commands set loadpath
?commands show loadpath
?set loadpath
?show loadpath
?loadpath
 The `loadpath` setting defines additional locations for data and command
 files searched by the `call`, `load`, `plot` and `splot` commands.  If a
 file cannot be found in the current directory, the directories in
 `loadpath` are tried.

 Syntax:
       set loadpath {"pathlist1" {"pathlist2"...}}
       show loadpath

 Path names may be entered as single directory names, or as a list of
 path names separated by a platform-specific path separator, eg. colon
 (':') on Unix, semicolon (';') on DOS/Windows/OS/2 platforms.
 The `show loadpath`, `save` and `save set` commands replace the
 platform-specific separator with a space character (' ').

 If the environment variable GNUPLOT_LIB is set, its contents are appended to
 `loadpath`.  However, `show loadpath` prints the contents of `set loadpath`
 and GNUPLOT_LIB separately.  Also, the `save` and `save set` commands ignore
 the contents of GNUPLOT_LIB.
?commands set locale
?set locale
?locale
 The `locale` setting determines the language with which `{x,y,z}{d,m}tics`
 will write the days and months.

 Syntax:
       set locale {"<locale>"}

 <locale> may be any language designation acceptable to your installation.
 See your system documentation for the available options.  The command
 `set locale ""` will try to determine the locale from the LC_TIME, LC_ALL,
 or LANG environment variables.

 To change the decimal point locale, see `set decimalsign`.
 To change the character encoding to the current locale, see `set encoding`.
?commands set logscale
?commands unset logscale
?commands show logscale
?set logscale
?unset logscale
?show logscale
?set log
?logscale
?nologscale
 Syntax:
       set logscale <axes> {<base>}
       unset logscale <axes>
       show logscale

 where <axes> may be any combinations of `x`, `x2`, `y`, `y2`, `z`, `cb`, and
 `r` in any order.  <base> is the base of the log scaling (default is base 10).
 If no axes are specified, the command affects all axes except `r`.
 The command `unset logscale` turns off log scaling for all axes.
 Note that the ticmarks generated for logscaled axes are not uniformly spaced.
 See `set xtics`.

 Examples:

 To enable log scaling in both x and z axes:
       set logscale xz

 To enable scaling log base 2 of the y axis:
       set logscale y 2

 To enable z and color log axes for a pm3d plot:
       set logscale zcb

 To disable z axis log scaling:
       unset logscale z
?commands set macros
?commands show macros
?set macros
?show macros
 If command line macro substitution is enabled, then tokens in the command line
 of the form @<stringvariablename> will be replaced by the text string contained
 in <stringvariablename>. See `substitution`.

 Syntax:
      set macros

?commands set mapping
?commands show mapping
?set mapping
?show mapping
?mapping
 If data are provided to `splot` in spherical or cylindrical coordinates,
 the `set mapping` command should be used to instruct `gnuplot` how to
 interpret them.

 Syntax:
       set mapping {cartesian | spherical | cylindrical}

 A cartesian coordinate system is used by default.

 For a spherical coordinate system, the data occupy two or three columns
 (or `using` entries).  The first two are interpreted as the azimuthal
 and polar angles theta and phi (or "longitude" and "latitude"), in the
 units specified by `set angles`.  The radius r is taken from the third
 column if there is one, or is set to unity if there is no third column.
 The mapping is:

       x = r * cos(theta) * cos(phi)
       y = r * sin(theta) * cos(phi)
       z = r * sin(phi)

 Note that this is a "geographic" spherical system, rather than a "polar"
 one (that is, phi is measured from the equator, rather than the pole).

 For a cylindrical coordinate system, the data again occupy two or three
 columns.  The first two are interpreted as theta (in the units specified by
 `set angles`) and z.  The radius is either taken from the third column or set
 to unity, as in the spherical case.  The mapping is:

       x = r * cos(theta)
       y = r * sin(theta)
       z = z

 The effects of `mapping` can be duplicated with the `using` filter on the
 `splot` command, but `mapping` may be more convenient if many data files are
 to be processed.  However even if `mapping` is used, `using` may still be
 necessary if the data in the file are not in the required order.

 `mapping` has no effect on `plot`.
 world.dem: mapping demos.
?commands set margin
?commands show margin
?set margin
?show margin
?margin
 The `margin` is the distance between the plot border and the outer edge of the
 canvas. The size of the margin is chosen automatically, but can be overridden
 by the `set margin` commands.  `show margin` shows the current settings.
 To alter the distance between the inside of the plot border and the data in the
 plot itself, see `set offsets`.

 Syntax:
       set bmargin {{at screen} <margin>}
       set lmargin {{at screen} <margin>}
       set rmargin {{at screen} <margin>}
       set tmargin {{at screen} <margin>}
       show margin

 The default units of <margin> are character heights or widths, as appropriate.
 A positive value defines the absolute size of the margin.  A negative value
 (or none) causes `gnuplot` to revert to the computed value.  For 3D plots,
 only the left margin can be set using character units.

 The keywords `at screen` indicates that the margin is specified as a fraction
 of the full drawing area. This can be used to precisely line up the corners of
 individual 2D and 3D graphs in a multiplot. This placement ignores the current
 values of `set origin` and `set size`, and is intended as an alternative 
 method for positioning graphs within a multiplot.

 Normally the margins of a plot are automatically calculated based on tics,
 tic labels, axis labels, the plot title, the timestamp and the size of the
 key if it is outside the borders.  If, however, tics are attached to the
 axes (`set xtics axis`, for example), neither the tics themselves nor their
 labels will be included in either the margin calculation or the calculation
 of the positions of other text to be written in the margin.  This can lead
 to tic labels overwriting other text if the axis is very close to the border.
?commands set mouse
?commands unset mouse
?set mouse
?unset mouse
?mousing
?mouse
?nomouse
 The command `set mouse` enables mouse actions for the current interactive
 terminal.  It is usually enabled by default in interactive mode, but disabled
 by default if commands are being read from a file.
 
 There are two mouse modes. The 2D mode works for `plot` commands and for `splot`
 maps (i.e. `set view` with z-rotation 0, 90, 180, 270 or 360 degrees, including
 `set view map`).  In this mode the mouse position is tracked and you can pan or
 zoom using the mouse buttons or arrow keys.  Some terminals support toggling
 individual plots on/off by clicking on the corresponding key title or on a
 separate widget.

 For 3D graphs `splot`, the view and scaling of the graph can be changed with
 mouse buttons 1 and 2, respectively. A vertical motion of Button 2 with the
 shift key held down changes the `xyplane`.  If additionally to these
 buttons the modifier <ctrl> is held down, the coordinate axes are displayed
 but the data are suppressed.  This is useful for large data sets.

 Mousing is not available inside multiplot mode. When multiplot is completed
 using `unset multiplot`, then the mouse will be turned on again but acts only
 on the most recent plot within the multiplot (like replot does).

 Syntax:
       set mouse {doubleclick <ms>} {nodoubleclick} \
                 {{no}zoomcoordinates} \
                 {noruler | ruler {at x,y}} \
                 {polardistance{deg|tan} | nopolardistance} \
                 {format <string>} \
                 {clipboardformat <int>/<string>} \
                 {mouseformat <int>/<string>} \
                 {{no}labels {"labeloptions"}} \
                 {{no}zoomjump} {{no}verbose}
       unset mouse

 The options `noruler` and `ruler` switch the ruler off and on, the latter
 optionally setting the origin at the given coordinates. While the ruler is on,
 the distance in user units from the ruler origin to the mouse is displayed
 continuously. By default, toggling the ruler has the key binding 'r'.

 The option `polardistance` determines if the distance between the mouse cursor
 and the ruler is also shown in polar coordinates (distance and angle in
 degrees or tangent (slope)). This corresponds to the default key binding '5'.

 Choose the option `labels` to define persistent gnuplot labels using Button 2.
 The default is `nolabels`, which makes Button 2 draw only a temporary label at
 the mouse position. Labels are drawn with the current setting of `mouseformat`.
 The `labeloptions` string is passed to the `set label` command.  The default is
 "point pointstyle 1" which will plot a small plus at the label position.
 Temporary labels will disappear at the next `replot` or mouse zoom operation.
 Persistent labels can be removed by holding the Ctrl-Key down while clicking
 Button 2 on the label's point. The threshold for how close you must be to the
 label is also determined by the `pointsize`.

 If the option `verbose` is turned on the communication commands are shown
 during execution. This option can also be toggled by hitting `6` in the
 driver's window. `verbose` is off by default.

 Press 'h' in the driver's window for a short summary of the mouse and key
 bindings.  This will also display user defined bindings or `hotkeys` which
 can be defined using the `bind` command, see help for `bind`.  Note, that user
 defined `hotkeys` may override the default bindings.
 See also help for `bind` and `label`.
?set mouse doubleclick
?mouse doubleclick
 The doubleclick resolution is given in milliseconds and used for Button 1,
 which copies the current mouse position to the `clipboard`.  The default value
 is 300 ms.  Setting the value to 0 ms triggers the copy on a single click.
?set mouse format
?set mouse mouseformat
?mouse format
?mouseformat
 The `set mouse format` command specifies a format string for sprintf() which
 determines how the mouse cursor [x,y] coordinates are printed to the plot
 window and to the clipboard.  The default is "% #g".

 `set mouse clipboardformat` and `set mouse mouseformat` are used for formatting
 the text on Button1 and Button2 actions -- copying the coordinates to the
 clipboard and temporarily annotating the mouse position.  An integer argument
 selects one of the format options in the table below. A string argument is used
 as a format for sprintf() in option 6 and should contain two float specifiers.
 Example:
      `set mouse mouseformat "mouse x,y = %5.2g, %10.3f"`.
 Use `set mouse mouseformat ""` to turn this string off again.

 The following formats are available:

  0   default (same as 1)
  1   axis coordinates                    1.23, 2.45
  2   graph coordinates (from 0 to 1)    /0.00, 1.00/
  3   x = timefmt     y = axis           [(as set by `set timefmt`), 2.45]
  4   x = date        y = axis           [31. 12. 1999, 2.45]
  5   x = time        y = axis           [23:59, 2.45]
  6   x = date time   y = axis           [31. 12. 1999 23:59, 2.45]
  7   format from `set mouse mouseformat`, e.g. "mouse x,y = 1.23,     2.450"
?set mouse scrolling
?mouse scrolling
?mouse wheel
?scrolling
?mousewheel
 X and Y axis scaling in both 2D and 3D graphs can be adjusted using the
 mouse wheel.  <wheel-up> scrolls up (increases both YMIN and YMAX by ten
 percent of the Y range, and increases both Y2MIN and Y2MAX likewise), and
 <wheel down> scrolls down.  <shift-wheel-up> scrolls left (decreases both
 XMIN and XMAX, and both X2MIN and X2MAX), and <shift-wheel-down> scrolls
 right.  <control-wheel-up> zooms in toward the center of the plot, and
 <control-wheel-down> zooms out.  <shift-control-wheel-up> zooms in along the
 X and X2 axes only, and <shift-control-wheel-down> zooms out along the X and
 X2 axes only.
?mouse x11_mouse
?x11_mouse
?x11 mouse
 If multiple X11 plot windows have been opened using the `set term x11 <n>`
 terminal option, then only the current plot window supports the entire
 range of mouse commands and hotkeys.  The other windows will, however,
 continue to display mouse coordinates at the lower left.
?mouse zoom
?zoom
 Zooming is usually accomplished by holding down the left mouse button and 
 dragging the mouse to delineate a zoom region.  Some platforms may require
 using a different mouse button.  The original plot can be restored by typing
 the 'u' hotkey in the plot window.  The hotkeys 'p' and 'n' step back and
 forth through a history of zoom operations.

 The option `zoomcoordinates` determines if the coordinates of the zoom box are
 drawn at the edges while zooming. This is on by default.

 If the option `zoomjump` is on, the mouse pointer will be automatically
 offset a small distance after starting a zoom region with button 3. This can
 be useful to avoid a tiny (or even empty) zoom region. `zoomjump` is off by
 default.

?commands set multiplot
?commands unset multiplot
?set multiplot
?unset multiplot
?multiplot
?nomultiplot
 The command `set multiplot` places `gnuplot` in the multiplot mode, in which
 several plots are placed on the same page, window, or screen.

 Syntax:
       set multiplot
           { title <page title> {font <fontspec>} {enhanced|noenhanced} }
           { layout <rows>,<cols> 
             {rowsfirst|columnsfirst} {downwards|upwards}
             {scale <xscale>{,<yscale>}} {offset <xoff>{,<yoff>}}
           }
       unset multiplot

 For some terminals, no plot is displayed until the command `unset multiplot`
 is given, which causes the entire page to be drawn and then returns gnuplot
 to its normal single-plot mode.  For other terminals, each separate `plot`
 command produces an updated display, either by redrawing all previous ones
 and the newly added plot, or by just adding the new plot to the existing
 display.

 The area to be used by the next plot is not erased before doing the
 new plot.  The `clear` command can be used to do this if wanted, as is
 typically the case for "inset" plots.

 Any labels or arrows that have been defined will be drawn for each plot
 according to the current size and origin (unless their coordinates are
 defined in the `screen` system).  Just about everything else that can be
 `set` is applied to each plot, too.  If you want something to appear only
 once on the page, for instance a single time stamp, you'll need to put a `set
 time`/`unset time` pair around one of the `plot`, `splot` or `replot`
 commands within the `set multiplot`/`unset multiplot` block.

 The multiplot title is separate from the individual plot titles, if any.
 Space is reserved for it at the top of the page, spanning the full width
 of the canvas.

 The commands `set origin` and `set size` must be used to correctly position
 each plot if no layout is specified or if fine tuning is desired.  See
 `set origin` and `set size` for details of their usage.

 Example:
       set multiplot
       set size 0.4,0.4
       set origin 0.1,0.1
       plot sin(x)
       set size 0.2,0.2
       set origin 0.5,0.5
       plot cos(x)
       unset multiplot

 This displays a plot of cos(x) stacked above a plot of sin(x).

 `set size` and `set origin` refer to the entire plotting area used for each
 plot.  Please also see `set term size`.  If you want to have the axes
 themselves line up, you can guarantee that the margins are the same size with
 the `set margin` commands.  See `set margin` for their use.  Note that the
 margin settings are absolute, in character units, so the appearance of the
 graph in the remaining space will depend on the screen size of the display
 device, e.g., perhaps quite different on a video display and a printer.

 With the `layout` option you can generate simple multiplots without having
 to give the `set size` and `set origin` commands before each plot:  Those
 are generated automatically, but can be overridden at any time.  With
 `layout` the display will be divided by a grid with <rows> rows and
 <cols> columns.  This grid is filled rows first or columns first depending on
 whether the corresponding option is given in the multiplot command.  The stack
 of plots can grow `downwards` or `upwards`.
 Default is `rowsfirst` and `downwards`.

 Each plot can be scaled by `scale` and shifted with `offset`; if the y-values
 for scale or offset are omitted, the x-value will be used.  `unset multiplot`
 will turn off the automatic layout and restore the values of `set size` and
 `set origin` as they were before `set multiplot layout`.

 Example:
       set size 1,1
       set origin 0,0
       set multiplot layout 3,2 columnsfirst scale 1.1,0.9
       [ up to 6 plot commands here ]
       unset multiplot

 The above example will produce 6 plots in 2 columns filled top to bottom,
 left to right.  Each plot will have a horizontal size of 1.1/2 and a vertical
 size of 0.9/3.

 See also
 multiplot demo (multiplt.dem)
?commands set mx2tics
?commands unset mx2tics
?commands show mx2tics
?set mx2tics
?unset mx2tics
?show mx2tics
?mx2tics
?nomx2tics
 Minor tic marks along the x2 (top) axis are controlled by `set mx2tics`.
 Please see `set mxtics`.
?commands set mxtics
?commands unset mxtics
?commands show mxtics
?set mxtics
?unset mxtics
?show mxtics
?mxtics
?nomxtics
 Minor tic marks along the x axis are controlled by `set mxtics`.  They can be
 turned off with `unset mxtics`.  Similar commands control minor tics along
 the other axes.

 Syntax:
       set mxtics {<freq> | default}
       unset mxtics
       show mxtics

 The same syntax applies to `mytics`, `mztics`, `mx2tics`, `my2tics` and
 `mcbtics`.

 <freq> is the number of sub-intervals (NOT the number of minor tics) between
 major tics (the default for a linear axis is either two or five
 depending on the major tics, so there are one or four minor
 tics between major tics). Selecting `default` will return the number of minor
 ticks to its default value.

 If the axis is logarithmic, the number of sub-intervals will be set to a
 reasonable number by default (based upon the length of a decade).  This will
 be overridden if <freq> is given.  However the usual minor tics (2, 3, ...,
 8, 9 between 1 and 10, for example) are obtained by setting <freq> to 10,
 even though there are but nine sub-intervals.

 To set minor tics at arbitrary positions, use the ("<label>" <pos> <level>,
 ...) form of `set {x|x2|y|y2|z}tics` with <label> empty and <level> set to 1.

 The `set m{x|x2|y|y2|z}tics` commands work only when there are uniformly
 spaced major tics.  If all major tics were placed explicitly by
 `set {x|x2|y|y2|z}tics`, then minor tic commands are ignored.  Implicit
 major tics and explicit minor tics can be combined using
 `set {x|x2|y|y2|z}tics` and `set {x|x2|y|y2|z}tics add`.

 Examples:
       set xtics 0, 5, 10
       set xtics add (7.5)
       set mxtics 5
 Major tics at 0,5,7.5,10, minor tics at 1,2,3,4,6,7,8,9
       set logscale y
       set ytics format ""
       set ytics 1e-6, 10, 1
       set ytics add ("1" 1, ".1" 0.1, ".01" 0.01, "10^-3" 0.001, \
                      "10^-4" 0.0001)
       set mytics 10
 Major tics with special formatting, minor tics at log positions

 By default, minor tics are off for linear axes and on for logarithmic axes.
 They inherit the settings for `axis|border` and `{no}mirror` specified for
 the major tics.  Please see `set xtics` for information about these.
?commands set my2tics
?commands unset my2tics
?commands show my2tics
?set my2tics
?unset my2tics
?show my2tics
?my2tics
?nomy2tics
 Minor tic marks along the y2 (right-hand) axis are controlled by `set
 my2tics`.  Please see `set mxtics`.
?commands set mytics
?commands unset mytics
?commands show mytics
?set mytics
?unset mytics
?show mytics
?mytics
?nomytics
 Minor tic marks along the y axis are controlled by `set mytics`.  Please
 see `set mxtics`.
?commands set mztics
?commands unset mztics
?commands show mztics
?set mztics
?unset mztics
?show mztics
?mztics
?nomztics
 Minor tic marks along the z axis are controlled by `set mztics`.  Please
 see `set mxtics`.
?object
?commands set object
?commands show object
?set object
?show object
 The `set object` command defines a single object which will appear in all
 subsequent 2D plots. You may define as many objects as you like. Currently the
 supported object types are `rectangle`, `circle`, `ellipse`, and `polygon`.
 Rectangles inherit a default set of style properties (fill, color, border) from
 those set by the command `set style rectangle`, but each object can also be
 given individual style properties. Circles, ellipses, and polygons  inherit the
 fill style from `set style fill`.

 Syntax:
     set object <index>
         <object-type> <object-properties>
         {front|back|behind} {fc|fillcolor <colorspec>} {fs <fillstyle>}
         {default} {lw|linewidth <width>}

 <object-type> is either `rectangle`, `ellipse`, `circle`, or `polygon`.
 Each object type has its own set of characteristic properties.

 Setting `front` will draw the object in front of all plot elements, but
 behind any labels that are also marked `front`. Setting `back` will place the
 object behind all plot curves and labels. Setting `behind` will place the
 object behind everything including the axes and `back` rectangles, thus
     set object rectangle from screen 0,0 to screen 1,1 behind
 can be used to provide a colored background for the entire graph or page.

 The fill color of the object is taken from the <colorspec>. `fillcolor`
 may be abbreviated `fc`.  The fill style is taken from <fillstyle>.
 See `colorspec` and `fillstyle`.  If the keyword `default` is given,
 these properties are inherited from the default settings at the time a plot
 is drawn. See `set style rectangle`.
?rectangle
?commands set object rectangle
?commands show object rectangle
?set object rectangle
?show object rectangle
 Syntax:
     set object <index> rectangle
         {from <position> {to|rto} <position> |
          center <position> size <w>,<h> |
          at <position> size <w>,<h>}

 The position of the rectangle may be specified by giving the position of two
 diagonal corners (bottom left and top right) or by giving the position of the
 center followed by the width and the height.  In either case the positions
 may be given in axis, graph, or screen coordinates. See `coordinates`.
 The options `at` and `center` are synonyms.

 Examples:
     # Force the entire area enclosed by the axes to have background color cyan
     set object 1 rect from graph 0, graph 0 to graph 1, graph 1 back
     set object 1 rect fc rgb "cyan" fillstyle solid 1.0

     # Position a red square with lower left at 0,0 and upper right at 2,3
     set object 2 rect from 0,0 to 2,3 fc lt 1

     # Position an empty rectangle (no fill) with a blue border
     set object 3 rect from 0,0 to 2,3 fs empty border rgb "blue"

     # Return fill and color to the default style but leave vertices unchanged
     set object 2 rect default

 Rectangle corners specified in screen coordinates may extend beyond the edge of
 the current graph. Otherwise the rectangle is clipped to fit in the graph.

?ellipse
?commands set object ellipse
?commands show object ellipse
?set object ellipse
?show object ellipse
 Syntax:
     set object <index> ellipse {at|center} <position> size <w>,<h>
         {angle <orientation>} {units xy|xx|yy}
         {<other-object-properties>}

 The position of the ellipse is specified by giving the center followed by
 the width and the height (actually the major and minor axes). The keywords
 `at` and `center` are synonyms.  The center position may be given in axis,
 graph, or screen coordinates. See `coordinates`. The major and minor axis
 lengths must be given in axis coordinates.  The orientation of the ellipse
 is specified by the angle between the horizontal axis and the major diameter
 of the ellipse.  If no angle is given, the default ellipse orientation
 will be used instead (see `set style ellipse`).  The `units` keyword
 controls the scaling of the axes of the ellipse. `units xy` means that the
 major axis is interpreted in terms of units along the x axis, while the 
 minor axis in that of the y axis. `units xx` means that both axes of the 
 ellipses are scaled in the units of the x axis, while `units yy` means 
 that both axes are in units of the y axis. 
 The default is `xy` or whatever `set style ellipse units` was set to.

 NB: If the x and y axis scales are not equal, (e.g. `units xy` is in
 effect) then the major/minor axis ratio will no longer be correct after
 rotation.

 Note that `set object ellipse size <2r>,<2r>` does not in general produce
 the same result as `set object circle <r>`.  The circle radius is always
 interpreted in terms of units along the x axis, and will always produce a
 circle even if the x and y axis scales are different and even if the aspect
 ratio of your plot is not 1.  If `units` is set to `xy`, then
 'set object ellipse' interprets the first <2r> in terms of x axis units 
 and the second <2r> in terms of y axis units. This will only produce a
 circle if the x and y axis scales are identical and the plot aspect ratio
 is 1.  On the other hand, if `units` is set to `xx` or `yy`, then the
 diameters specified in the 'set object' command will be interpreted in the
 same units, so the ellipse will have the correct aspect ratio, and it will
 maintain its aspect ratio even if the plot is resized.

?circle
?commands set object circle
?commands show object circle
?set object circle
?show object circle
 Syntax:
     set object <index> circle {at|center} <position> size <radius>
         {arc [<begin>:<end>]}
         {<other-object-properties>}

 The position of the circle is specified by giving the position of the center
 center followed by the radius.  The keywords `at` and `center` are synonyms.
 The position and radius may be given in x-axis, graph, or canvas
 coordinates. See `coordinates`. In all cases the radius is calculated
 relative to the horizontal scale of the axis, graph, or canvas.  Any
 disparity between the horizontal and vertical scaling will be corrected for
 so that the result is always a circle.

 By default a full circle is drawn. The optional qualifier `arc` specifies
 a starting angle and ending angle, in degrees, for one arc of the circle.
 The arc is always drawn counterclockwise.

?polygon
?commands set object polygon
?commands show object polygon
?set object polygon
?show object polygon
 Syntax:
     set object <index> polygon
         from <position> to <position> ... {to <position>}
 or
         from <position> rto <position> ... {rto <position>}

 The position of the polygon may be specified by giving the position of a
 sequence of vertices. These may be given in axis, graph, or screen coordinates.
 If relative coordinates are used (rto) then the coordinate type must match
 that of the previous vertex.
 See `coordinates`.

 Example:
     set object 1 polygon from 0,0 to 1,1 to 2,0
     set object 1 fc rgb "cyan" fillstyle solid 1.0 border lt -1

?commands set offsets
?commands unset offsets
?commands show offsets
?set offsets
?unset offsets
?show offsets
?offsets
?nooffsets
 Offsets provide a mechanism to put an empty boundary around the data inside
 an autoscaled graph.  The offsets only affect the x1 and y1 axes, and only in
 2D `plot` commands.

 Syntax:
       set offsets <left>, <right>, <top>, <bottom>
       unset offsets
       show offsets

 Each offset may be a constant or an expression.  Each defaults to 0.
 By default, the left and right offsets are given in units of the first x axis,
 the top and bottom offsets in units of the first y axis.  Alternatively, you
 may specify the offsets as a fraction of the total axis range by using the
 keyword "graph".  A positive offset expands the axis range in the specified
 direction, e.g., a positive bottom offset makes ymin more negative.  Negative
 offsets, while permitted, can have unexpected interactions with autoscaling
 and clipping.  To prevent the auto-scaling from further adjusting your axis
 ranges, it is useful to also specify "set auto fix".

 Example:
       set auto fix
       set offsets graph 0.05, 0, 2, 2
       plot sin(x)

 This graph of sin(x) will have a y range [-3:3] because the function
 will be autoscaled to [-1:1] and the vertical offsets are each two.
 The x range will be [-11:10] because the default is [-10:10] and it has
 been expanded to the left by 0.05 of that total range.
?commands set origin
?commands show origin
?set origin
?show origin
?origin
 The `set origin` command is used to specify the origin of a plotting surface
 (i.e., the graph and its margins) on the screen.  The coordinates are given
 in the `screen` coordinate system (see `coordinates` for information about
 this system).

 Syntax:
       set origin <x-origin>,<y-origin>
?commands set output
?commands show output
?set output
?show output
?output
?output file
 By default, screens are displayed to the standard output. The `set output`
 command redirects the display to the specified file or device.

 Syntax:
       set output {"<filename>"}
       show output

 The filename must be enclosed in quotes.  If the filename is omitted, any
 output file opened by a previous invocation of `set output` will be closed
 and new output will be sent to STDOUT.  (If you give the command `set output
 "STDOUT"`, your output may be sent to a file named "STDOUT"!  ["May be", not
 "will be", because some terminals, like `x11` or `wxt`, ignore `set output`.])

 When both `set terminal` and `set output` are used together, it is safest to
 give `set terminal` first, because some terminals set a flag which is needed
 in some operating systems.  This would be the case, for example, if the
 operating system needs to know whether or not a file is to be formatted in
 order to open it properly.

 On machines with popen functions (Unix), output can be piped through a shell
 command if the first non-whitespace character of the filename is '|'.
 For instance,

       set output "|lpr -Plaser filename"
       set output "|lp -dlaser filename"

 On MSDOS machines, `set output "PRN"` will direct the output to the default
 printer.  On VMS, output can be sent directly to any spooled device.  It is
 also possible to send the output to DECnet transparent tasks, which allows
 some flexibility.
?commands set parametric
?commands unset parametric
?commands show parametric
?set parametric
?unset parametric
?show parametric
?parametric
?noparametric
 The `set parametric` command changes the meaning of `plot` (`splot`) from
 normal functions to parametric functions.  The command `unset parametric`
 restores the plotting style to normal, single-valued expression plotting.

 Syntax:
       set parametric
       unset parametric
       show parametric

 For 2D plotting, a parametric function is determined by a pair of parametric
 functions operating on a parameter.  An example of a 2D parametric function
 would be `plot sin(t),cos(t)`, which draws a circle (if the aspect ratio is
 set correctly---see `set size`).  `gnuplot` will display an error message if
 both functions are not provided for a parametric `plot`.

 For 3D plotting, the surface is described as x=f(u,v), y=g(u,v), z=h(u,v).
 Therefore a triplet of functions is required.  An example of a 3D parametric
 function would be `cos(u)*cos(v),cos(u)*sin(v),sin(u)`, which draws a sphere.
 `gnuplot` will display an error message if all three functions are not
 provided for a parametric `splot`.

 The total set of possible plots is a superset of the simple f(x) style plots,
 since the two functions can describe the x and y values to be computed
 separately.  In fact, plots of the type t,f(t) are equivalent to those
 produced with f(x) because the x values are computed using the identity
 function.  Similarly, 3D plots of the type u,v,f(u,v) are equivalent to
 f(x,y).

 Note that the order the parametric functions are specified is xfunction,
 yfunction (and zfunction) and that each operates over the common parametric
 domain.

 Also, the `set parametric` function implies a new range of values.  Whereas
 the normal f(x) and f(x,y) style plotting assume an xrange and yrange (and
 zrange), the parametric mode additionally specifies a trange, urange, and
 vrange.  These ranges may be set directly with `set trange`, `set urange`,
 and `set vrange`, or by specifying the range on the `plot` or `splot`
 commands.  Currently the default range for these parametric variables is
 [-5:5].  Setting the ranges to something more meaningful is expected.
?commands show plot
?show plot
 The `show plot` command shows the current plotting command as it results
 from the last `plot` and/or `splot` and possible subsequent `replot` commands.

 In addition, the `show plot add2history` command adds this current plot
 command into the `history`. It is useful if you have used `replot` to add
 more curves to the current plot and you want to edit the whole command now.
?commands set pm3d
?commands show pm3d
?set pm3d
?show pm3d
?pm3d
 pm3d is an `splot` style for drawing palette-mapped 3d and 4d data as
 color/gray maps and surfaces.  It uses an algorithm that allows plotting
 gridded as well as non-gridded data without preprocessing, even when the data
 scans do not have the same number of points.

 Syntax (the options can be given in any order):
       set pm3d {
                  { at <position> }
                  { interpolate <steps/points in scan, between scans> }
                  { scansautomatic | scansforward | scansbackward | depthorder }
                  { flush { begin | center | end } }
                  { ftriangles | noftriangles }
                  { clip1in | clip4in }
                  { corners2color { mean|geomean|median|min|max|c1|c2|c3|c4 } }
                  { hidden3d {<linestyle>} | nohidden3d }
                  { implicit | explicit }
                  { map }
                }
       show pm3d
       unset pm3d

 A pm3d color surface is drawn if the splot command specifies `with pm3d`,  
 if the data or function `style` is set to pm3d globally, or if the pm3d mode is
 `set pm3d implicit`.  In the latter two cases, the pm3d surface is draw in
 addition to the mesh produced by the style specified in the plot command. E.g.
       splot 'fred.dat' with lines, 'lola.dat' with lines
 would draw both a mesh of lines and a pm3d surface for each data set.
 If the option `explicit` is on (or `implicit` is off) only plots specified
 by the `with pm3d` attribute are plotted with a pm3d surface, e.g.:
       splot 'fred.dat' with lines, 'lola.dat' with pm3d
 would plot 'fred.dat' with lines (only) and 'lola.dat' with a pm3d surface.

 On gnuplot start-up, the mode is `explicit`. For historical and compatibility
 reasons, the commands `set pm3d;` (i.e. no options) and `set pm3d at X ...`
 (i.e.  `at` is the first option) change the mode to `implicit`.
 The command `set pm3d;` sets other options to their default state.

 If you set the default data or function style to `pm3d`, e.g.:
       set style data pm3d
 then the options `implicit` and `explicit` have no effect.

 Note that when plotting several plots, they are plotted in the order given
 on the command line. This can be of interest especially for filled surfaces
 which can overwrite and therefore hide part of earlier plots.

 The pm3d coloring can be drawn at any or all of three different positions,
 `top`, `bottom`, or `surface`. See `pm3d position`.
 The following command draws three color surfaces at different altitudes:
       set border 4095
       set pm3d at s
       splot 10*x with pm3d at b, x*x-y*y, x*x+y*y with pm3d at t

 See also help for `set palette`, `set cbrange`, `set colorbox`, 
 and definitely the demo file `demo/pm3d.dem`.
?pm3d algorithm

 Let us first describe how a map/surface is drawn.  The input data come from an
 evaluated function or from an `splot data file`.  Each surface consists of a
 sequence of separate scans (isolines).  The pm3d algorithm fills the region
 between two neighbouring points in one scan with another two points in the
 next scan by a gray (or color) according to z-values (or according to an
 additional 'color' column, see help for `using`) of these 4 corners; by default
 the 4 corner values are averaged, but this can be changed by the option
 `corners2color`.  In order to get a reasonable surface, the neighbouring scans
 should not cross and the number of points in the neighbouring scans should not
 differ too much; of course, the best plot is with scans having same number of
 points.  There are no other requirements (e.g. the data need not be gridded).
 Another advantage is that the pm3d algorithm does not draw anything outside of
 the input (measured or calculated) region.

 Surface coloring works with the following input data:

 1. splot of function or of data file with one or three data columns: The
 gray/color scale is obtained by mapping the averaged (or `corners2color`)
 z-coordinate of the four corners of the above-specified quadrangle into the
 range [min_color_z,max_color_z] of `zrange` or `cbrange` providing a gray value
 in the range [0:1].  This value can be used directly as the gray for gray maps.
 The normalized gray value can be further mapped into a color---see `set palette`
 for the complete description.

 2. splot of data file with two or four data columns: The gray/color value is
 obtained by using the last-column coordinate instead of the z-value, thus
 allowing the color and the z-coordinate be mutually independent.  This can be
 used for 4d data drawing.

 Other notes:

 1. The term 'scan' referenced above is used more among physicists than the
 term 'iso_curve' referenced in gnuplot documentation and sources.  You measure
 maps recorded one scan after another scan, that's why.

 2. The 'gray' or 'color' scale is a linear mapping of a continuous variable
 onto a smoothly varying palette of colors. The mapping is shown in a
 rectangle next to the main plot. This documentation refers to this as a
 "colorbox", and refers to the indexing variable as lying on the colorbox axis.
 See `set colorbox`, `set cbrange`.

 3. To use pm3d coloring to generate a two-dimensional plot rather than a 3D
 surface, use `set view map` or `set pm3d map`.
?pm3d position
 Color surface can be drawn at the base or top (then it is a gray/color planar
 map) or at z-coordinates of surface points (gray/color surface).  This is
 defined by the `at` option with a string of up to 6 combinations of `b`, `t`
 and `s`. For instance, `at b` plots at bottom only, `at st` plots firstly
 surface and then top map, while `at bstbst` will never by seriously used.

 Colored quadrangles are plotted one after another.  When plotting surfaces
 (`at s`), the later quadrangles overlap (overdraw) the previous ones.
 (Gnuplot is not virtual reality tool to calculate intersections of filled
 polygon meshes.)  You may try to switch between `scansforward` and
 `scansbackward` to force the first scan of the data to be plotted first or
 last.  The default is `scansautomatic` where gnuplot makes a guess about scans
 order.  On the other hand, the `depthorder` option completely reorders the
 quadrangles. The rendering is performed after a depth sorting, which allows to
 visualize even complicated surfaces; see `pm3d depthorder` for more details.
?pm3d scanorder
?pm3d depthorder
?pm3d flush
?depthorder
 By default the quadrangles making up a pm3d solid surface are rendered in the
 order they are encountered along the surface grid points.  This order may be
 controlled by the options `scansautomatic`|`scansforward`|`scansbackward`.
 These scan options are not in general compatible with hidden-surface removal.

 If two successive scans do not have same number of points, then it has to be
 decided whether to start taking points for quadrangles from the beginning of
 both scans (`flush begin`), from their ends (`flush end`) or to center them
 (`flush center`).  Note, that `flush (center|end)` are incompatible with
 `scansautomatic`: if you specify `flush center` or `flush end` and
 `scansautomatic` is set, it is silently switched to `scansforward`.

 If two subsequent scans do not have the same number of points, the option
 `ftriangles` specifies whether color triangles are drawn at the scan tail(s)
 where there are not enough points in either of the scan. This can be used to
 draw a smooth map boundary.

 Gnuplot does not do true hidden surface removal for solid surfaces, but often
 it is sufficient to render the component quadrangles in order from furthest
 to closest.  This mode may be selected using the options
       set pm3d depthorder hidden3d
 The `depthorder` option orders the solid quadrangles; the `hidden3d` option
 similarly orders the bounding lines (if drawn).  Note that the global option
 `set hidden3d` does not affect pm3d surfaces.

?pm3d clipping
 Clipping with respect to x, y coordinates of quadrangles can be done in two
 ways.  `clip1in`: all 4 points of each quadrangle must be defined and at least
 1 point of the quadrangle must lie in the x and y ranges.  `clip4in`: all 4
 points of each quadrangle must lie in the x and y ranges.

?pm3d color_assignment
 `3 columns of data (x,y,z)`:

 The coloring setup as well as the color box drawing are determined by
 `set palette`.  There can be only one palette for the current plot.  Drawing
 of several surfaces with different palettes can be achieved by `multiplot`
 with fixed `origin` and `size`; don't forget to use `set palette maxcolors`
 when your terminal is running out of available colors.

 There is a single gray/color value associated to each drawn pm3d quadrangle
 (no smooth color change among vertices).  The value is calculated from
 z-coordinates from the surrounding corners according to `corners2color
 <option>`.  The options 'mean' (default), 'geomean' and 'median' produce
 various kinds of surface color smoothing, while options 'min' and 'max' choose
 minimal or maximal value, respectively. This may not be desired for pixel
 images or for maps with sharp and intense peaks, in which case the options
 'c1', 'c2', 'c3' or 'c4' can be used instead to assign the quadrangle color
 based on the z-coordinate of only one corner.  Some experimentation may be
 needed to determine which corner corresponds to 'c1', as the orientation
 depends on the drawing direction.  Because the pm3d algorithm does not extend
 the colored surface outside the range of the input data points, the 'c<j>'
 coloring options will result in pixels along two edges of the grid not
 contributing to the color of any quadrangle.  For example, applying the pm3d
 algorithm to the 4x4 grid of data points in script `demo/pm3d.dem` (please have
 a look) produces only (4-1)x(4-1)=9 colored rectangles.

 `4 columns of data (x,y,z,color)`:

 If a fourth column of data is provided, it is normally interpreted as a 
 separate palette-mapped gray value. The coloring of individual quadrangles
 works as above, except that the color value is distinct from the z value.
 As a separate coloring option, the fourth data column may provide instead
 an RGB color. See `rgbcolor variable`. In this case the plotting command
 must be

       splot ... using 1:2:3:4 with pm3d lc rgb variable

 Another drawing algorithm, which would draw quadrangles around a given node
 by taking corners from averaged (x,y)-coordinates of its surrounding 4 nodes
 while using node's color, could be implemented in the future. This is already
 done for drawing images (2D grids) via `image` and `rgbimage` styles.

 Notice that ranges of z-values and color-values for surfaces are adjustable
 independently by `set zrange`, `set cbrange`, as well as `set log` for z or
 cb.  Maps can be adjusted by the cb-axis only; see also `set view map` and
 `set colorbox`.
?set pm3d hidden3d
?pm3d hidden3d
 The option `set pm3d hidden3d` draws the bounding lines of each quadrangle
 at the same time that the quadrangle itself is drawn. Normally it is used in
 conjunction with the `depthorder` option to achieve an approximation to true
 hidden line removal.  This is far more efficient than using the command
 `set hidden3d`.  The command takes an optional linestyle controlling the
 appearance of the bounding lines.  If the linestyle parameter is negative,
 or omitted, then the line properties given in the plot command are used.
 Example of recommended usage:

       set pm3d at s hidden3d depthorder
       unset hidden3d
       unset surf
       splot x*x+y*y linecolor rgb "black" linewidth 0.5

?set pm3d interpolate
?pm3d interpolate
 The option `interpolate m,n` will interpolate grid points into a finer mesh,
 and color each quadrangle appropriately.  For data files, this will smoothen
 the color surface, and enhance spikes in a color surface. For functions,
 interpolation makes little sense, except to trade off precision for memory.
 It would usually make more sense to use `samples` and `isosamples` when
 working with functions. For positive m and n, each quadrangle or triangle
 is interpolated m-times and n-times in the respective direction.  For negative
 m and n, the interpolation frequency is chosen so that there will be at least
 |m| and |n| points drawn; you can consider this as a special gridding function.
 Zeros, i.e. `interpolate 0,0`, will automatically choose an optimal number of
 interpolated surface points.
?pm3d deprecated_options
 There used to be an option {transparent|solid} to this command.  Now
 you get the same effect from `set grid {front|layerdefault}`, respectively.

 The command `set pm3d map` is equivalent to `set pm3d at b`; `set view map`;
 `set style data pm3d`; `set style func pm3d`;.
 It is used for backwards compatibility, when `set view map` was not available.
 Take care that you properly use `zrange` and `cbrange` for input data point
 filtering and color range scaling, respectively; and also `set (no)surface`
 seems to have a (side?) effect.
?commands set palette
?commands show palette
?set palette
?show palette
?palette
 Palette is a color storage for use by `pm3d`, filled color contours or
 polygons, color histograms, color gradient background, and whatever it is
 or it will be implemented...  Here it stands for a palette of smooth
 "continuous" colors or grays, but let's call it just a palette.

 Color palettes require terminal entries for filled color polygons and
 palettes of smooth colors, are currently available for terminals listed in
 help for `set pm3d`. The range of color values are adjustable independently by
 `set cbrange` and `set log cb`. The whole color palette is
 visualized in the `colorbox`.

 Syntax:
       set palette
       set palette {
                  { gray | color }
                  { gamma <gamma> }
                  {   rgbformulae <r>,<g>,<b>
                    | defined { ( <gray1> <color1> {, <grayN> <colorN>}... ) }
                    | file '<filename>' {datafile-modifiers}
                    | functions <R>,<G>,<B>
                  }
                  { cubehelix {start <val>} {cycles <val>} {saturation <val>} }
                  { model { RGB | HSV | CMY | YIQ | XYZ } }
                  { positive | negative }
                  { nops_allcF | ps_allcF }
                  { maxcolors <maxcolors> }
                }
       show palette
       show palette palette <n> {{float | int}}
       show palette gradient
       show palette fit2rgbformulae
       show palette rgbformulae
       show colornames

 `set palette` (i.e. without options) sets up the default values.
 Otherwise, the options can be given in any order.
 `show palette` shows the current palette properties.

 `show palette gradient` displays the gradient defining the palette (if
 appropriate).  `show palette rgbformulae` prints the available fixed gray -->
 color transformation formulae.  `show colornames` prints the known color names.

 `show palette palette <n>` prints to the screen or to the file given by
 `set print` a table of RGB triplets calculated for the current palette settings
 and a palette having <n> discrete colors.  The default wide table can be
 limited to 3 columns of r,g,b float values [0..1] or integer values [0..255]
 by options float or int, respectively.  This way, the current gnuplot color
 palette can be loaded into other imaging applications, for example Octave.
 Additionally to this textual list of RGB table, you can use the `test palette`
 command to plot the R,G,B profiles for the current palette.

 The following options determine the coloring properties.

 Figure using this palette can be `gray` or `color`.  For instance, in `pm3d`
 color surfaces the gray of each small spot is obtained by mapping the averaged
 z-coordinate of the 4 corners of surface quadrangles into the range
 [min_z,max_z] providing range of grays [0:1]. This value can be used directly
 as the gray for gray maps. The color map requires a transformation gray -->
 (R,G,B), i.e. a mapping [0:1] --> ([0:1],[0:1],[0:1]).

 Basically two different types of mappings can be used:  Analytic formulae to
 convert gray to color, or discrete mapping tables which are interpolated.
 `palette rgbformulae` and `palette functions` use analytic formulae whereas
 `palette defined` and `palette file` use interpolated tables.  `palette
 rgbformulae` reduces the size of postscript output to a minimum.

 The command `show palette fit2rgbformulae` finds the best matching `set
 palette rgbformulae` for the current `set palette`. Naturally, it makes sense
 to use it for non-rgbformulae palettes. This command can be found useful
 mainly for external programs using the same rgbformulae definition of palettes
 as gnuplot, like zimg (
           http://zimg.sourceforge.net
 ).

 `set palette gray` switches to a gray only palette. `set palette rgbformulae`,
 `set palette defined`, `set palette file` and `set palette functions` switch
 to a color mapping. `set palette color` is an easy way to switch back from the
 gray palette to the last color mapping.

 Automatic gamma correction via `set palette gamma <gamma>` can be done for
 gray maps (`set palette gray`) and for the `cubehelix` color palette schemes.
 Gamma = 1 produces a linear ramp of intensity. See `test palette`.

 Many terminals support only discrete number of colors (e.g. 256 colors in gif).
 After the default gnuplot linetype colors are allocated, the rest of the
 available colors are by default reserved for pm3d.  Thus a multiplot using
 multiple palettes could fail because the first palette has used all the
 available color positions.  You can mitigate this limitation by using
 `set palette maxcolors <N>` with a reasonably small value of N.
 This option causes N discrete colors to be selected from a continuous palette
 sampled at equally spaced intervals.  If you want unequal spacing of N
 discrete colors, use `set palette defined` instead of a single continuous
 palette.

 RGB color space might not be the most useful color space to work in.  For that
 reason you may change the color space with `model` to one of `RGB`, `HSV`,
 `CMY`, `YIQ` and `XYZ`.  Using color names for `set palette defined` tables
 and a color space other than RGB will result in funny colors.  All explanation
 have been written for RGB color space, so please note, that `R` can be `H`,
 `C`, `Y`, or `X`, depending on the actual color space (`G` and `B`
 accordingly).

 All values for all color spaces are limited to [0,1].

 RGB stands for Red, Green and Blue;  CMY stands for Cyan, Magenta and Yellow;
 HSV stands for Hue, Saturation, and Value;  YIQ is the color model used by
 the U.S. Commercial Color Television Broadcasting, it is basically an RGB
 recoding with downward compatibility for black and white television;
 XYZ are the three primary colors of the color model defined by the 'Commission
 Internationale de l'Eclairage' (CIE).
 For more information on color models see:
           http://en.wikipedia.org/wiki/Color_space

?commands set palette rgbformulae
?set palette rgbformulae
?palette rgbformulae
?rgbformulae
 For `rgbformulae` three suitable mapping functions have
 to be chosen.  This is done via `rgbformulae <r>,<g>,<b>`.  The available
 mapping functions are listed by `show palette rgbformulae`.  Default is
 `7,5,15`, some other examples are `3,11,6`, `21,23,3` or `3,23,21`.  Negative
 numbers, like `3,-11,-6`, mean inverted color (i.e.  1-gray passed into the
 formula, see also `positive` and `negative` options below).

 Some nice schemes in RGB color space
    7,5,15   ... traditional pm3d (black-blue-red-yellow)
    3,11,6   ... green-red-violet
    23,28,3  ... ocean (green-blue-white); try also all other permutations
    21,22,23 ... hot (black-red-yellow-white)
    30,31,32 ... color printable on gray (black-blue-violet-yellow-white)
    33,13,10 ... rainbow (blue-green-yellow-red)
    34,35,36 ... AFM hot (black-red-yellow-white)

 A full color palette in HSV color space
    3,2,2    ... red-yellow-green-cyan-blue-magenta-red

 Please note that even if called `rgbformulae` the formulas might actually
 determine the <H>,<S>,<V> or <X>,<Y>,<Z> or ... color components as usual.

 Use `positive` and `negative` to invert the figure colors.

 Note that it is possible to find a set of the best matching rgbformulae for any
 other color scheme by the command
    show palette fit2rgbformulae
?commands set palette defined
?set palette defined
?palette defined
 Gray-to-rgb mapping can be manually set by use of `palette defined`:
 A color gradient is defined and used to give the rgb values.  Such a gradient
 is a piecewise linear mapping from gray values in [0,1] to the RGB space
 [0,1]x[0,1]x[0,1].  You must specify the gray values and the corresponding RGB
 values between which linear interpolation will be done.

 Syntax:
       set palette  defined { ( <gray1> <color1> {, <grayN> <colorN>}... ) }

 <grayX> are gray values which are mapped to [0,1] and <colorX> are the
 corresponding rgb colors.  The color can be specified in three different
 ways:

      <color> :=  { <r> <g> <b> | '<color-name>' | '#rrggbb' }

 Either by three numbers (each in [0,1]) for red, green and blue, separated by
 whitespace, or the name of the color in quotes or X style color specifiers
 also in quotes.  You may freely mix the three types in a gradient definition,
 but the named color "red" will be something strange if RGB is not selected
 as color space.  Use `show colornames` for a list of known color names.

 Please note, that even if written as <r>, this might actually be the
 <H> component in HSV color space or <X> in CIE-XYZ space, or ...
 depending on the selected color model.

 The <gray> values have to form an ascending sequence of real numbers; the
 sequence will be automatically rescaled to [0,1].

 `set palette defined` (without a gradient definition in braces) switches to
 RGB color space and uses a preset full-spectrum color gradient.
 Use `show palette gradient` to display the gradient.

 Examples:

 To produce a gray palette (useless but instructive) use:
       set palette model RGB
       set palette defined ( 0 "black", 1 "white" )

 To produce a blue yellow red palette use (all equivalent):
       set palette defined ( 0 "blue", 1 "yellow", 2 "red" )
       set palette defined ( 0 0 0 1, 1 1 1 0, 2 1 0 0 )
       set palette defined ( 0 "#0000ff", 1 "#ffff00", 2 "#ff0000" )

 To produce some rainbow-like palette use:
       set palette defined ( 0 "blue", 3 "green", 6 "yellow", 10 "red" )

 Full color spectrum within HSV color space:
       set palette model HSV
       set palette defined ( 0 0 1 1, 1 1 1 1 )
       set palette defined ( 0 0 1 0, 1 0 1 1, 6 0.8333 1 1, 7 0.8333 0 1)

 Approximate the default palette used by MATLAB:
       set pal defined (1 '#00008f', 8 '#0000ff', 24 '#00ffff', \
                        40 '#ffff00', 56 '#ff0000', 64 '#800000')

 To produce a palette with only a few, equally-spaced colors:
       set palette model RGB maxcolors 4
       set palette defined ( 0 "yellow", 1 "red" )

 'Traffic light' palette (non-smooth color jumps at gray = 1/3 and 2/3).
       set palette model RGB
       set palette defined (0 "dark-green", 1 "green", \
                            1 "yellow",     2 "dark-yellow", \
                            2 "red",        3 "dark-red" )

?commands set palette functions
?set palette functions
?palette functions
 Use `set palette functions <Rexpr>, <Gexpr>, <Bexpr>` to define three formulae
 for the R(gray), G(gray) and B(gray) mapping.  The three formulae may depend
 on the variable `gray` which will take values in [0,1] and should also
 produce values in [0,1].
 Please note that <Rexpr> might be a formula for the H-value if HSV color
 space has been chosen (same for all other formulae and color spaces).

 Examples:

 To produce a full color palette use:
       set palette model HSV functions gray, 1, 1

 A nice black to gold palette:
       set palette model XYZ functions gray**0.35, gray**0.5, gray**0.8

 A gamma-corrected black and white palette
       gamma = 2.2
       color(gray) = gray**(1./gamma)
       set palette model RGB functions color(gray), color(gray), color(gray)

?commands set palette cubehelix
?set palette cubehelix
?cubehelix
 The "cubehelix" option defines a family of palettes in which color (hue) varies
 along the standard color wheel while at the same time the net intensity 
 increases monotonically as the gray value goes from 0 to 1.
       D A Green (2011) http://arxiv.org/abs/1108.5083
 `start` defines the starting point along the color wheel in radians.
 `cycles` defines how many color wheel cycles span the palette range.
 Larger values of `saturation` produce more saturated color; saturation > 1
 may lead to clipping of the individual RGB components and to intensity
 becoming non-monotonic. The palette is also affected by `set palette gamma`.
 The default values are
       set palette cubehelix start 0.5 cycles -1.5 saturation 1
       set palette gamma 1.5

?commands set palette file
?set palette file
?palette file
 `set palette file` is basically a `set palette defined (<gradient>)` where
 <gradient> is read from a datafile.  Either 4 columns (gray,R,G,B) or
 just three columns (R,G,B) have to be selected via the `using` data file
 modifier.  In the three column case, the line number will be used as gray.
 The gray range is automatically rescaled to [0,1].  The file is read as a
 normal data file, so all datafile modifiers can be used.
 Please note, that `R` might actually be e.g. `H` if HSV color space is
 selected.

 As usual <filename> may be `'-'` which means that the data follow the command
 inline and are terminated by a single `e` on a line of its own.

 Use `show palette gradient` to display the gradient.

 Examples:

 Read in a palette of RGB triples each in range [0,255]:
       set palette file 'some-palette' using ($1/255):($2/255):($3/255)

 Equidistant rainbow (blue-green-yellow-red) palette:
       set palette model RGB file "-"
       0 0 1
       0 1 0
       1 1 0
       1 0 0
       e

 Binary palette files are supported as well, see `binary general`. Example:
 put 64 triplets of R,G,B doubles into file palette.bin and load it by
       set palette file "palette.bin" binary record=64 using 1:2:3


?commands set palette gamma-correction
?set palette gamma-correction
?palette gamma-correction
?gamma-correction
 For gray mappings gamma correction can be turned on by `set palette gamma
 <gamma>`.  <gamma> defaults to 1.5 which is quite suitable for most
 terminals.

 The gamma correction is applied to the cubehelix color palette family, but not
 to other palette coloring schemes. However, you may easily implement gamma
 correction for explicit color functions.

 Example:
       set palette model RGB
       set palette functions gray**0.64, gray**0.67, gray**0.70

 To use gamma correction with interpolated gradients specify intermediate
 gray values with appropriate colors.  Instead of

       set palette defined ( 0 0 0 0, 1 1 1 1 )

 use e.g.

       set palette defined ( 0 0 0 0, 0.5 .73 .73 .73, 1 1 1 1 )

 or even more intermediate points until the linear interpolation fits the
 "gamma corrected" interpolation well enough.

?commands set palette postscript
?set palette postscript
 In order to reduce the size of postscript files, the gray value and not all
 three calculated r,g,b values are written to the file.  Therefore the
 analytical formulae are coded directly in the postscript language as a header
 just before the pm3d drawing, see /g and /cF definitions.  Usually, it makes
 sense to write therein definitions of only the 3 formulae used.  But for
 multiplot or any other reason you may want to manually edit the
 transformations directly in the postscript file.  This is the default option
 `nops_allcF`.  Using the option `ps_allcF` writes postscript definitions of
 all formulae.  This you may find interesting if you want to edit the
 postscript file in order to have different palettes for different surfaces
 in one graph.  Well, you can achieve this functionality by `multiplot` with
 fixed `origin` and `size`.

 If pm3d map has been plotted from gridded or almost regular data with an
 output to a postscript file, then it is possible to reduce the size of this
 postscript file up to at about 50% by the enclosed awk script
 `pm3dCompress.awk`.  This you may find  interesting if you intend to keep the
 file for including it into your publication or before downloading a very large
 file into a slow printer. Usage:
     awk -f pm3dCompress.awk thefile.ps >smallerfile.ps

 If pm3d map has been plotted from rectangular gridded data with an output
 to a postscript file, then it is possible to reduce the file size even more
 by the enclosed awk script `pm3dConvertToImage.awk`.  Usage:
     awk -f pm3dConvertToImage.awk <thefile.ps >smallerfile.ps

 You may manually change the postscript output from gray to color and vice
 versa and change the definition of <maxcolors>.
?commands set pointintervalbox
?set pointintervalbox
?pointintervalbox
 The `pointinterval` property of line types is used in plot style `linespoints`.
 A negative value of pointinterval, e.g. -N, means that point symbols are drawn
 only for every Nth point, and that a box (actually circle) behind each point
 symbol is blanked out by filling with the background color.  The command
 `set pointintervalbox` controls the radius of this blanked-out region.
 It is a multiplier for the default radius, which is equal to the point size.
?commands set pointsize
?commands show pointsize
?set pointsize
?show pointsize
?pointsize
 The `set pointsize` command scales the size of the points used in plots.

 Syntax:
       set pointsize <multiplier>
       show pointsize

 The default is a multiplier of 1.0.  Larger pointsizes may be useful to
 make points more visible in bitmapped graphics.

 The pointsize of a single plot may be changed on the `plot` command.
 See `plot with` for details.

 Please note that the pointsize setting is not supported by all terminal
 types.
?commands set polar
?commands unset polar
?commands show polar
?set polar
?unset polar
?show polar
?polar
?nopolar
 The `set polar` command changes the meaning of the plot from rectangular
 coordinates to polar coordinates.

 Syntax:
       set polar
       unset polar
       show polar

 In polar coordinates, the dummy variable (t) is an angle.  The default range
 of t is [0:2*pi], or, if degree units have been selected, to [0:360] (see
 `set angles`).

 The command `unset polar` changes the meaning of the plot back to the default
 rectangular coordinate system.

 The `set polar` command is not supported for `splot`s.  See the `set mapping`
 command for similar functionality for `splot`s.

 While in polar coordinates the meaning of an expression in t is really
 r = f(t), where t is an angle of rotation.  The trange controls the domain
 (the angle) of the function. The r, x and y ranges control the extent of the
 graph in the x and y directions.  Each of these ranges, as well as the
 rrange, may be autoscaled or set explicitly.  For details, see `set rrange`
 and `set xrange`.

 Example:
       set polar
       plot t*sin(t)
       set trange [-2*pi:2*pi]
       set rrange [0:3]
       plot t*sin(t)

 The first `plot` uses the default polar angular domain of 0 to 2*pi.  The
 radius and the size of the graph are scaled automatically.  The second `plot`
 expands the domain, and restricts the size of the graph to the area within
 3 units of the origin.  This has the effect of limiting x and y to [-3:3].

 You may want to `set size square` to have `gnuplot` try to make the aspect
 ratio equal to unity, so that circles look circular.
 See also
 polar demos (polar.dem)
 and
 polar data plot (poldat.dem).
?commands set print
?commands show print
?set print
?show print
 The `set print` command redirects the output of the `print` command to a file.

 Syntax:
       set print
       set print "-"
       set print "<filename>"
       set print "<filename>" append
       set print "|<shell_command>"

 Without "<filename>", the output file is restored to <STDERR>.  The <filename>
 "-" means <STDOUT>. The `append` flag causes the file to be opened in append
 mode.  A <filename> starting with "|" is opened as a pipe to the
 <shell_command> on platforms that support piping.
?commands set psdir
?commands show psdir
?set psdir
?show psdir
?psdir
 The `set psdir <directory>` command controls the search path used by the
 postscript terminal to find prologue.ps and character encoding files.
 You can use this mechanism to switch between different sets of
 locally-customized prolog files.
 The search order is
       1) The directory specified by `set psdir`, if any
       2) The directory specified by environmental variable GNUPLOT_PS_DIR
       3) A built-in header or one from the default system directory
       4) Directories set by `set loadpath`
?commands set raxis
?raxis
 The commands `set raxis` and `unset raxis` toggle whether the polar axis
 is drawn separately from grid lines and the x axis.  If the minimum of the
 current rrange is non-zero (and not autoscaled), then a white circle is drawn
 at the center of the polar plot to indicate that the plot lines and axes do
 not reach 0.  The axis line is drawn using the same line type as the plot
 border.  See `polar`, `rrange`, `rtics`, `set grid`.
?commands set rmargin
?set rmargin
?rmargin
 The command `set rmargin` sets the size of the right margin.
 Please see `set margin` for details.
?commands set rrange
?commands show rrange
?set rrange
?show rrange
?rrange
 The `set rrange` command sets the range of the radial coordinate for a graph
 in polar mode.  This has the effect of setting both xrange and yrange as well.
 The resulting xrange and yrange are both [-(rmax-rmin) : +(rmax-rmin)].
 However if you later change the x or y range, for example by zooming, this does
 not change rrange, so data points continue to be clipped against rrange.
 Autoscaling of rmin always results in rmin = 0.
?commands set rtics
?commands show rtics
?set rtics
?show rtics
?rtics
 The `set rtics` command places tics along the polar axis. These will only be
 shown in polar plot mode.  The tics and labels are drawn to the right of the
 origin. The `mirror` keyword causes them to be drawn also to the left of the
 origin. See `polar`, and see `set xtics` for discussion of other keywords.
?commands set samples
?commands show samples
?set samples
?show samples
?samples
 The sampling rate of functions, or for interpolating data, may be changed
 by the `set samples` command.

 Syntax:
       set samples <samples_1> {,<samples_2>}
       show samples

 By default, sampling is set to 100 points.  A higher sampling rate will
 produce more accurate plots, but will take longer.  This parameter has no
 effect on data file plotting unless one of the interpolation/approximation
 options is used.  See `plot smooth` re 2D data and `set cntrparam` and
 `set dgrid3d` re 3D data.

 When a 2D graph is being done, only the value of <samples_1> is relevant.

 When a surface plot is being done without the removal of hidden lines, the
 value of samples specifies the number of samples that are to be evaluated for
 the isolines.  Each iso-v line will have <sample_1> samples and each iso-u
 line will have <sample_2> samples.  If you only specify <samples_1>,
 <samples_2> will be set to the same value as <samples_1>.  See also
 `set isosamples`.
?commands set size
?commands show size
?set size
?show size
?size
?aspect ratio
?set size square
?set size ratio
?ratio
 Syntax:
       set size {{no}square | ratio <r> | noratio} {<xscale>,<yscale>}
       show size

 The <xscale> and <yscale> values are scale factors for the size of the plot,
 which includes the graph, labels, and margins.

 Important note:
       In earlier versions of gnuplot, some terminal types used the values from
       `set size` to control also the size of the output canvas; others did not.
       In version 4.6 almost all terminals now follow the following convention:

 `set term <terminal_type> size <XX>, <YY>` controls the size of the output
 file, or `canvas`. Please see individual terminal documentation for allowed
 values of the size parameters.  By default, the plot will fill this canvas.

 `set size <XX>, <YY>` scales the plot itself relative to the size of the
 canvas.  Scale values less than 1 will cause the plot to not fill the entire
 canvas.  Scale values larger than 1 will cause only a portion of the plot to
 fit on the canvas.  Please be aware that setting scale values larger than 1
 may cause problems on some terminal types.

 `ratio` causes `gnuplot` to try to create a graph with an aspect ratio of <r>
 (the ratio of the y-axis length to the x-axis length) within the portion of
 the plot specified by <xscale> and <yscale>.

 The meaning of a negative value for <r> is different.  If <r>=-1, gnuplot
 tries to set the scales so that the unit has the same length on both the x
 and y axes.  This is equivalent to `set view equal xy`.  See `set view equal`.
 If <r>=-2, the unit on y has twice the length of the unit on x, and so on.

 The success of `gnuplot` in producing the requested aspect ratio depends on
 the terminal selected.  The graph area will be the largest rectangle of
 aspect ratio <r> that will fit into the specified portion of the output
 (leaving adequate margins, of course).

 `square` is a synonym for `ratio 1`.

 Both `noratio` and `nosquare` return the graph to the default aspect ratio
 of the terminal, but do not return <xscale> or <yscale> to their default
 values (1.0).

 `ratio` and `square` have no effect on 3D plots, but do affect 3D projections
 created using `set view map`.  See also `set view equal`, which forces
 the x and y axes of a 3D onto the same scale.

 Examples:

 To set the size so that the plot fills the available canvas:
       set size 1,1

 To make the graph half size and square use:
       set size square 0.5,0.5

 To make the graph twice as high as wide use:
       set size ratio 2

?set style
?show style
?unset style
 Default plotting styles are chosen with the `set style data` and
 `set style function` commands.  See `plot with` for information about how to
 override the default plotting style for individual functions and data sets.
 See `plotting styles` for a complete list of styles.

 Syntax:
       set style function <style>
       set style data <style>
       show style function
       show style data

 Default styles for specific plotting elements may also be set.

 Syntax:
       set style arrow <n> <arrowstyle>
       set style fill <fillstyle>
       set style histogram <histogram style options>
       set style line <n> <linestyle>

 If `gnuplot` was built with the support of objects, then the following
 options are also available:

 Syntax:
       set style rectangle <object options> <linestyle> <fillstyle>
       set style circle radius <size>
       set style ellipse size <size> units {xy|xx|yy}

?commands set style arrow
?commands unset style arrow
?commands show style arrow
?set style arrow
?unset style arrow
?show style arrow
?arrowstyle
 Each terminal has a default set of arrow and point types, which can be seen
 by using the command `test`.  `set style arrow` defines a set of arrow types
 and widths and point types and sizes so that you can refer to them later by
 an index instead of repeating all the information at each invocation.

 Syntax:
       set style arrow <index> default
       set style arrow <index> {nohead | head | heads}
                               {size <length>,<angle>{,<backangle>}}
                               {filled | empty | nofilled}
                               {front | back}
                               { {linestyle | ls <line_style>}
                                 | {linetype | lt <line_type>}
                                   {linewidth | lw <line_width} }
       unset style arrow
       show style arrow

 <index> is an integer that identifies the arrowstyle.

 If `default` is given all arrow style parameters are set to their default
 values.

 If the linestyle <index> already exists, only the given parameters are
 changed while all others are preserved.  If not, all undefined values are
 set to the default values.

 Specifying `nohead` produces arrows drawn without a head---a line segment.
 This gives you yet another way to draw a line segment on the plot.  By
 default, arrows have one head. Specifying `heads` draws arrow heads on both
 ends of the line.

 Head size can be controlled by `size <length>,<angle>` or
 `size <length>,<angle>,<backangle>`, where `<length>` defines length of each
 branch of the arrow head and `<angle>` the angle (in degrees) they make with
 the arrow.  `<Length>` is in x-axis units; this can be changed by `first`,
 `second`, `graph`, `screen`, or `character` before the <length>;  see
 `coordinates` for details.  `<Backangle>` only takes effect when `filled`
 or `empty` is also used.  Then, `<backangle>` is the angle (in degrees) the
 back branches make with the arrow (in the same direction as `<angle>`).
 The `fig` terminal has a restricted backangle function. It supports three
 different angles. There are two thresholds: Below 70 degrees, the arrow head
 gets an indented back angle. Above 110 degrees, the arrow head has an acute
 back angle. Between these thresholds, the back line is straight.

 Specifying `filled` produces filled arrow heads (if heads are used).
 Filling is supported on filled-polygon capable terminals, see help of `pm3d`
 for their list, otherwise the arrow heads are closed but not filled.
 The same result (closed but not filled arrow head) is reached by specifying
 `empty`.  Further, filling and outline is obviously not supported on
 terminals drawing arrows by their own specific routines, like `metafont`,
 `metapost`, `latex` or `tgif`.

 The line style may be selected from a user-defined list of line styles
 (see `set style line`) or may be defined here by providing values for
 `<line_type>` (an index from the default list of styles) and/or
 `<line_width>` (which is a  multiplier for the default width).

 Note, however, that if a user-defined line style has been selected, its
 properties (type and width) cannot be altered merely by issuing another
 `set style arrow` command with the appropriate index and `lt` or `lw`.

 If `front` is given, the arrows are written on top of the graphed data. If
 `back` is given (the default), the arrow is written underneath the graphed
 data.  Using `front` will prevent a arrow from being obscured by dense data.

 Examples:

 To draw an arrow without an arrow head and double width, use:
       set style arrow 1 nohead lw 2
       set arrow arrowstyle 1

 See also `set arrow` for further examples.

?commands set style boxplot
?commands unset style boxplot
?commands show style boxplot
?set style boxplot
?unset style boxplot
?show style boxplot
 The `set style boxplot` command allows you to change the layout of plots
 created using the `boxplot` plot style.

 Syntax:
       set style boxplot {range <r> | fraction <f>}
                         {{no}outliers} {pointtype <p>}
                         {candlesticks | financebars}
                         {separation <x>}
                         {labels off | auto | x | x2}
                         {sorted | unsorted}

 The box in the boxplot always spans the range of values from the first
 quartile to the third quartile of the data points.  The limit of the whiskers
 that extend from the box can be controlled in two different ways. By default
 the whiskers extend from each end of the box for a range equal to 1.5 times
 the interquartile range (i.e. the vertical height of the box proper).
 Each whisker is truncated back toward the median so that it terminates at a
 y value belonging to some point in the data set. Since there may be no point
 whose value is exactly 1.5 times the interquartile distance, the whisker may
 be shorter than its nominal range.  This default corresponds to 
       set style boxplot range 1.5

 Alternatively, you can specify the fraction of the total number of points
 that the whiskers should span.  In this case the range is extended 
 symmetrically from the median value until it encompasses the requested fraction
 of the data set.  Here again each whisker is constrained to end at a point in
 the data set.  To span 95% of the points in the set
       set style boxplot fraction 0.95

 Any points that lie outside the range of the whiskers are considered outliers.
 By default these are drawn as individual circles (pointtype 7).  The option
 `nooutliers` disables this.

 By default boxplots are drawn in a style similar to candlesticks, but you have
 the option of using instead a style similar to finance bars.
 
 If the using specification for a boxplot contains a fourth column, the values
 in that column will be interpreted as the discrete leveles of a factor 
 variable.  In this case more than one boxplots may be drawn, as many as the
 number of levels of the factor variable.  These boxplots will be drawn next to
 each other, the distance between them is 1.0 by default (in x-axis units).
 This distance can be changed by the option `separation`.
 
 The `labels` option governs how and where these boxplots (each representing a
 part of the dataset) are labeled.  By default the value of the factor is put 
 as a tick label on the horizontal axis -- x or x2, depending on which one is
 used for the plot itself.  This setting corresponds to option `labels auto`.
 The labels can be forced to use either of the x or x2 axes -- options
 `labels x` and `labels x2`, respectively --, or they can be turned off
 altogether with the option `labels off`.
 
 By default the boxplots corresponding to different levels of the factor
 variable are not sorted; they will be drawn in the same order the levels are
 encountered in the data file. This behavior corresponds to the `unsorted`
 option. If the `sorted` option is active, the levels are first sorted
 alphabetically, and the boxplots are drawn in the sorted order.

 The `separation`, `labels`, `sorted` and `unsorted` option only have an effect
 if a fourth column is given the plot specification.

 See `boxplot`, `candlesticks`, `financebars`.

?commands set style data
?commands show style data
?set style data
?show style data
?data style
 The `set style data` command changes the default plotting style for data
 plots.

 Syntax:
       set style data <plotting-style>
       show style data

 See `plotting styles` for the choices.  If no choice is given, the choices are
 listed.  `show style data` shows the current default data plotting style.
?commands set style fill
?commands show style fill
?set style fill
?show style fill
?fillstyle
 The `set style fill` command is used to set the default style of the plot
 elements in plots with boxes, histograms, candlesticks and filledcurves.
 This default can be superseded by fillstyles attached to individual plots.
 See also 'set style rectangle'.

 Syntax:
       set style fill {empty
                       | {transparent} solid {<density>}
                       | {transparent} pattern {<n>}}
                      {border {lt} {lc <colorspec>} | noborder}

 The default fillstyle is `empty`.

 The `solid` option causes filling with a solid color, if the terminal
 supports that. The <density> parameter specifies the intensity of the
 fill color. At a <density> of 0.0, the box is empty, at <density> of 1.0,
 the inner area is of the same color as the current linetype.
 Some terminal types can vary the density continuously; others implement
 only a few levels of partial fill.  If no <density> parameter is given,
 it defaults to 1.

 The `pattern` option causes filling to be done with a fill pattern supplied
 by the terminal driver.  The kind and number of available fill patterns
 depend on the terminal driver.  If multiple datasets using filled boxes are
 plotted, the pattern cycles through all available pattern types, starting
 from pattern <n>, much as the line type cycles for multiple line plots.

 The `empty` option causes filled boxes not to be filled. This is the default.

 By default, `border`, the box is bounded by a solid line of the current
 linetype. `border <colorspec>` allows you to change the color of the border.
 `noborder` specifies that no bounding lines are drawn.
?commands set style fill transparent
?set style fill transparent
?fillstyle transparent
?transparent
 Some terminals support the attribute `transparent` for filled areas.
 In the case of transparent solid fill areas, the `density` parameter is
 interpreted as an alpha value; that is, density 0 is fully transparent,
 density 1 is fully opaque.  In the case of transparent pattern fill, the
 background of the pattern is either fully transparent or fully opaque.

       terminal   solid pattern    pm3d
       --------------------------------
       gif           no     yes      no
       jpeg         yes      no     yes
       pdf          yes     yes     yes
       png    TrueColor   index     yes
       post          no     yes      no
       svg          yes      no     yes
       win          yes     yes     yes
       wxt          yes     yes     yes
       x11           no     yes      no


 Note that there may be additional limitations on the creation or viewing of
 graphs containing transparent fill areas.  For example, the png terminal can
 only use transparent fill if the "truecolor" option is set.  Some pdf viewers
 may not correctly display the fill areas even if they are correctly described
 in the pdf file. Ghostscript/gv does not correctly display pattern-fill areas
 even though actual PostScript printers generally have no problem.
?commands set style function
?commands show style function
?set style function
?show style function
 The `set style function` command changes the default plotting style for
 function plots (e.g. lines, points, filledcurves).  See `plotting styles`.

 Syntax:
       set style function <plotting-style>
       show style function
?commands set style increment
?commands show style increment
?set style increment
?show style increment
 `Note`:  This command has been deprecated.  Instead please use the newer
 command `set linetype`, which redefines the linetypes themselves rather
 than searching for a suitable temporary line style to substitute.
 See `set linetype`

 Syntax:
       set style increment {default|userstyles}
       show style increment

 By default, successive plots within the same graph will use successive
 linetypes from the default set for the current terminal type.
 However, choosing `set style increment user` allows you to step through
 the user-defined line styles rather than through the default linetypes.

 Example:

       set style line 1 lw 2 lc rgb "gold"
       set style line 2 lw 2 lc rgb "purple"
       set style line 4 lw 1 lc rgb "sea-green"
       set style increment user

       plot f1(x), f2(x), f3(x), f4(x)

 should plot functions f1, f2, f4 in your 3 newly defined line styles.
 If a user-defined line style is not found then the corresponding default
 linetype is used instead.  E.g. in the example above, f3(x) will be plotted
 using the default linetype 3.

?commands set style line
?commands unset style line
?commands show style line
?set style line
?unset style line
?show style line
?linestyle
?linewidth
 Each terminal has a default set of line and point types, which can be seen
 by using the command `test`.  `set style line` defines a set of line types
 and widths and point types and sizes so that you can refer to them later by
 an index instead of repeating all the information at each invocation.

 Syntax:
       set style line <index> default
       set style line <index> {{linetype  | lt} <line_type> | <colorspec>}
                              {{linecolor | lc} <colorspec>}
                              {{linewidth | lw} <line_width>}
                              {{pointtype | pt} <point_type>}
                              {{pointsize | ps} <point_size>}
                              {{pointinterval | pi} <interval>}
                              {palette}
       unset style line
       show style line

 `default` sets all line style parameters to those of the linetype with
 that same index.

 If the linestyle <index> already exists, only the given parameters are
 changed while all others are preserved.  If not, all undefined values are
 set to the default values.

 Line styles created by this mechanism do not replace the default linetype
 styles; both may be used.  Line styles are temporary. They are lost whenever
 you execute a `reset` command.  To redefine the linetype itself,
 please see `set linetype`.

 The line and point types default to the index value. The exact symbol that is
 drawn for that index value may vary from one terminal type to another.

 The line width and point size are multipliers for the current terminal's
 default width and size (but note that <point_size> here is unaffected by
 the multiplier given by the command`set pointsize`).

 The `pointinterval` controls the spacing between points in a plot drawn with
 style `linespoints`.  The default is 0 (every point is drawn). For example,
 `set style line N pi 3` defines a linestyle that uses pointtype N, pointsize
 and linewidth equal to the current defaults for the terminal, and will draw
 every 3rd point in plots using `with linespoints`.  A negative value for the
 interval is treated the same as a positive value, except that some terminals
 will try to interrupt the line where it passes through the point symbol.

 Not all terminals support the `linewidth` and `pointsize` features; if
 not supported, the option will be ignored.

 Terminal-independent colors may be assigned using either
 `linecolor <colorspec>` or `linetype <colorspec>`, abbreviated `lc` or `lt`.
 This requires giving a RGB color triple, a known palette color name,
 a fractional index into the current palette, or a constant value from the
 current mapping of the palette onto cbrange.
 See `colors`, `colorspec`, `set palette`, `colornames`, `cbrange`.

 `set style line <n> linetype <lt>` will set both a terminal-dependent dot/dash
 pattern and color. The commands`set style line <n> linecolor <colorspec>` or
 `set style line <n> linetype <colorspec>` will set a new line color while
 leaving the existing dot-dash pattern unchanged.

 In 3d mode (`splot` command), the special keyword `palette` is allowed as a
 shorthand for "linetype palette z".  The color value corresponds to the
 z-value (elevation) of the splot, and varies smoothly along a line or surface.

 Examples:
 Suppose that the default lines for indices 1, 2, and 3 are red, green, and
 blue, respectively, and the default point shapes for the same indices are a
 square, a cross, and a triangle, respectively.  Then

       set style line 1 lt 2 lw 2 pt 3 ps 0.5

 defines a new linestyle that is green and twice the default width and a new
 pointstyle that is a half-sized triangle.  The commands

       set style function lines
       plot f(x) lt 3, g(x) ls 1

 will create a plot of f(x) using the default blue line and a plot of g(x)
 using the user-defined wide green line.  Similarly the commands

       set style function linespoints
       plot p(x) lt 1 pt 3, q(x) ls 1

 will create a plot of p(x) using the default triangles connected by a red
 line and q(x) using small triangles connected by a green line.

       splot sin(sqrt(x*x+y*y))/sqrt(x*x+y*y) w l pal

 creates a surface plot using smooth colors according to `palette`. Note,
 that this works only on some terminals. See also `set palette`, `set pm3d`.

       set style line 10 linetype 1 linecolor rgb "cyan"

 will assign linestyle 10 to be a solid cyan line on any terminal that
 supports rgb colors.

?commands set style circle
?commands unset style circle
?commands show style circle
?set style circle
?unset style circle
?show style circle

 Syntax:
       set style circle {radius {graph|screen} <R>}

 This command sets the default radius used in plot style "with circles".  It
 applies to data plots with only 2 columns of data (x,y) and to function plots.
 The default is "set style circle radius graph 0.02".

?commands set style rectangle
?commands unset style rectangle
?commands show style rectangle
?set style rectangle
?unset style rectangle
?show style rectangle

 Rectangles defined with the `set object` command can have individual styles.
 However, if the object is not assigned a private style then it inherits a
 default that is taken from the `set style rectangle` command.

 Syntax:
     set style rectangle {front|back} {lw|linewidth <lw>}
                         {fillcolor <colorspec>} {fs <fillstyle>}

 See `colorspec` and `fillstyle`.  `fillcolor` may be abbreviated as `fc`.

 Examples:
     set style rectangle back fc rgb "white" fs solid 1.0 border lt -1
     set style rectangle fc linsestyle 3 fs pattern 2 noborder

 The default values correspond to solid fill with the background color and a
 black border.

?commands set style ellipse
?commands show style ellipse
?set style ellipse
?unset style ellipse
?show style ellipse

 Syntax:
       set style ellipse {units xx|xy|yy}
                         {size {graph|screen} <a>, {{graph|screen} <b>}}
                         {angle <angle>}

 This command governs whether the diameters of ellipses are interpreted in
 the same units or not.
 Default is `xy`, which means that the major diameter (first axis) of
 ellipses will be interpreted in the same units as the x (or x2) axis,
 while the minor (second) diameter in those of the y (or y2) axis.  
 In this mode the ratio of the ellipse axes depends on the scales of the
 plot axes and aspect ratio of the plot.  When set to `xx` or `yy`,
 both axes of all ellipses will be interpreted in the same units.
 This means that the ratio of the axes of the plotted ellipses will be
 correct even after rotation, but either their vertical or horizontal extent
 will not be correct.

 This is a global setting that affects all ellipses, both those defined as
 objects and those generated with the `plot` command, however, the value of
 `units` can also be redefined on a per-plot and per-object basis.

 It is also possible to set a default size for ellipses with the `size` 
 keyword.  This default size applies to data plots with only 
 2 columns of data (x,y) and to function plots.  The two values are 
 interpreted as the major and minor diameters (as opposed to semi-major 
 and semi-minor axes) of the ellipse.

 The default is "set style ellipse size graph 0.05,0.03".

 Last, but not least it is possible to set the default orientation with the
 `angle` keyword. The orientation, which is defined as the angle between the
 major axis of the ellipse and the plot's x axis, must be given in degrees.

 For defining ellipse objects, see `set object ellipse`;
 for the 2D plot style, see `ellipses`.

?commands set surface
?commands unset surface
?commands show surface
?set surface
?unset surface
?show surface
?surface
?nosurface
 The command `set surface` controls the display of surfaces by `splot`.

 Syntax:
       set surface
       unset surface
       show surface

 The surface is drawn with the style specified by `with`, or else the
 appropriate style, data or function.

 `unset surface` will cause `splot` to not draw points or lines corresponding
 to any of the function or data file points.  If you want to turn off the surface
 for an individual function or data file while leaving the others active, use
 the `nosurface` keyword in the `splot` command.  Contours may still be drawn on
 the surface, depending on the `set contour` option.  The combination
 `unset surface; set contour base` is useful for displaying contours on the grid
 base.  See also `set contour`. 
?commands set table
?set table
?table
 When `table` mode is enabled, `plot` and `splot` commands print out a
 multicolumn ASCII table of X Y {Z} R values rather than creating an actual
 plot on the current terminal.  The character R takes on one of three values:
 "i" if the point is in the active range, "o" if it is out-of-range, or "u"
 if it is undefined.  The data format is determined by the format of the axis
 labels (see `set format`), and the columns are separated by single spaces.
 This can be useful if you want to generate contours and then save them for
 further use, perhaps for plotting with `plot`;  see `set contour` for example.
 The same method can be used to save interpolated data
 (see `set samples` and `set dgrid3d`).

 Syntax:
       set table {"outfile"}
       plot <whatever>
       unset table

 Tabular output is written to the named file, if any, otherwise it is written
 to the current value of `set output`.  You must explicitly `unset table`
 in order to go back to normal plotting on the current terminal.
?commands set terminal
?commands show terminal
?set terminal
?set term
?show terminal
?show term
?set terminal push
?set term push
?terminal push
?term push
?push
?set terminal pop
?set term pop
?terminal pop
?term pop
?pop
 `gnuplot` supports many different graphics devices.  Use `set terminal` to
 tell `gnuplot` what kind of output to generate. Use `set output` to redirect
 that output to a file or device.

 Syntax:
       set terminal {<terminal-type> | push | pop}
       show terminal

 If <terminal-type> is omitted, `gnuplot` will list the available terminal
 types.  <terminal-type> may be abbreviated.

 If both `set terminal` and `set output` are used together, it is safest to
 give `set terminal` first, because some terminals set a flag which is needed
 in some operating systems.

 Some terminals have many additional options.
 The options used by a previous invocation `set term <term> <options>` of a
 given `<term>` are remembered, thus subsequent `set term <term>` does
 not reset them.  This helps in printing, for instance, when switching
 among different terminals---previous options don't have to be repeated.

 The command `set term push` remembers the current terminal including its
 settings while `set term pop` restores it. This is equivalent to `save term`
 and `load term`, but without accessing the filesystem. Therefore they can be
 used to achieve platform independent restoring of the terminal after printing,
 for instance. After gnuplot's startup, the default terminal or that from
 `startup` file is pushed automatically. Therefore portable scripts can rely
 that `set term pop` restores the default terminal on a given platform unless
 another terminal has been pushed explicitly.

 For more information, see the `complete list of terminals`.

?commands set termoption
?set termoption
?termoption
 The `set termoption` command allows you to change the behaviour of the
 current terminal without requiring a new `set terminal` command. Only one
 option can be changed per command, and only a small number of options can
 be changed this way. Currently the only options accepted are

      set termoption {no}enhanced
      set termoption font "<fontname>{,<fontsize>}"
      set termoption fontscale <scale>
      set termoption {solid|dashed}
      set termoption {linewidth <lw>}{lw <lw>}

?commands set tics
?commands unset tics
?commands show tics
?set tics
?unset tics
?show tics
?tics
 Control of the major (labelled) tics on all axes at once is possible with the
 `set tics` command.

 Fine control of the major (labelled) tics on all axes at once is possible
 with the `set tics` command.  The tics may be turned off with the `unset tics`
 command, and may be turned on (the default state) with `set tics`.  Similar
 commands (by preceding 'tics' by the axis name) control the major tics on a
 single axis.

 Syntax:
       set tics {axis | border} {{no}mirror}
                {in | out} {scale {default | <major> {,<minor>}}}
                {{no}rotate {by <ang>}} {offset <offset> | nooffset}
                {left | right | center | autojustify}
                { format "formatstring" } { font "name{,<size>}" }
                { textcolor <colorspec> }
       set tics {front | back}
       unset tics
       show tics

 The options in the first set above can be applied individually to
 any or all axes, i.e., x, y, z, x2, y2, and cb.

 Set tics `front` or `back` applies to all axes at once, but only for 2D plots
 (not splot).  It controls whether the tics are placed behind or in front of
 the plot elements, in the case that there is overlap.

 `axis` or `border` tells `gnuplot` to put the tics (both the tics themselves
 and the accompanying labels) along the axis or the border, respectively.  If
 the axis is very close to the border, the `axis` option will move the
 tic labels to outside the border in case the border is printed (see
 `set border`).  The relevant margin settings will usually be sized badly by
 the automatic layout algorithm in this case.

 `mirror` tells `gnuplot` to put unlabelled tics at the same positions on the
 opposite border.  `nomirror` does what you think it does.

 `in` and `out` change the tic marks to be drawn inwards or outwards.

 With `scale`, the size of the tic marks can be adjusted. If <minor> is not
 specified, it is 0.5*<major>.  The default size 1.0 for major tics and 0.5
 for minor tics is requested by `scale default`.

 `rotate` asks `gnuplot` to rotate the text through 90 degrees, which will be
 done if the terminal driver in use supports text rotation.  `norotate`
 cancels this. `rotate by <ang>` asks for rotation by <ang> degrees, supported
 by some terminal types.

 The defaults are `border mirror norotate` for tics on the x and y axes, and
 `border nomirror norotate` for tics on the x2 and y2 axes.  For the z axis,
 the default is `nomirror`.

 The <offset> is specified by either x,y or x,y,z, and may be preceded by
 `first`, `second`, `graph`, `screen`, or `character` to select the
 coordinate system. <offset> is the offset of the tics texts from their
 default positions, while the default coordinate system is `character`.
 See `coordinates` for details. `nooffset` switches off the offset.

 By default, tic labels are justified automatically depending on the axis and
 rotation angle to produce aesthetically pleasing results. If this is not
 desired, justification can be overridden with an explicit `left`, `right` or
 `center` keyword. `autojustify` restores the default behavior.

 `set tics` with no options restores to place tics inwards. Every other
 options are retained.

 See also `set xtics` for more control of major (labelled) tic marks and
 `set mxtics` for control of minor tic marks.  These commands provide control
 at a axis by axis basis.
?commands set ticslevel
?commands show ticslevel
?set ticslevel
?show ticslevel
?ticslevel
 Deprecated. See `set xyplane`.
?commands set ticscale
?commands show ticscale
?set ticscale
?show ticscale
?ticscale
 The `set ticscale` command is deprecated, use `set tics scale` instead.
?commands set timestamp
?commands unset timestamp
?commands show timestamp
?set timestamp
?unset timestamp
?show timestamp
?timestamp
?notimestamp
 The command `set timestamp` places the time and date of the plot in the left
 margin.

 Syntax:
       set timestamp {"<format>"} {top|bottom} {{no}rotate}
                     {offset <xoff>{,<yoff>}} {font "<fontspec>"}
       unset timestamp
       show timestamp

 The format string allows you to choose the format used to write the date and
 time.  Its default value is what asctime() uses: "%a %b %d %H:%M:%S %Y"
 (weekday, month name, day of the month, hours, minutes, seconds, four-digit
 year).  With `top` or `bottom` you can place the timestamp at the top or
 bottom of the left margin (default: bottom).  `rotate` lets you write the
 timestamp vertically, if your terminal supports vertical text.  The constants
 <xoff> and <yoff> are offsets that let you adjust the position more finely.
 <font> is used to specify the font with which the time is to be written.

 The abbreviation `time` may be used in place of `timestamp`.

 Example:
       set timestamp "%d/%m/%y %H:%M" offset 80,-2 font "Helvetica"

 See `set timefmt` for more information about time format strings.
?commands set timefmt
?commands show timefmt
?set timefmt
?show timefmt
?timefmt
 This command applies to timeseries where data are composed of dates/times.
 It has no meaning unless the command `set xdata time` is given also.

 Syntax:
       set timefmt "<format string>"
       show timefmt

 The string argument tells `gnuplot` how to read timedata from the datafile.
 The valid formats are:

       Format       Explanation
       %d           day of the month, 1--31
       %m           month of the year, 1--12
       %y           year, 0--99
       %Y           year, 4-digit
       %j           day of the year, 1--365
       %H           hour, 0--24
       %M           minute, 0--60
       %s           seconds since the Unix epoch (1970-01-01, 00:00 UTC)
       %S           second, integer 0--60 on output, (double) on input
       %b           three-character abbreviation of the name of the month
       %B           name of the month



 Any character is allowed in the string, but must match exactly.  \t (tab) is
 recognized.  Backslash-octals (\nnn) are converted to char.  If there is no
 separating character between the time/date elements, then %d, %m, %y, %H, %M
 and %S read two digits each.  If a decimal point immediately follows the field
 read by %S, the decimal and any following digits are interpreted as a
 fractional second.  %Y reads four digits. %j reads three digits.
 %b requires three characters, and %B requires as many as it needs.

 Spaces are treated slightly differently.  A space in the string stands for
 zero or more whitespace characters in the file.  That is, "%H %M" can be used
 to read "1220" and "12     20" as well as "12 20".

 Each set of non-blank characters in the timedata counts as one column in the
 `using n:n` specification.  Thus `11:11  25/12/76  21.0` consists of three
 columns.  To avoid confusion, `gnuplot` requires that you provide a complete
 `using` specification if your file contains timedata.

 If the date format includes the day or month in words, the format string must
 exclude this text.  But it can still be printed with the "%a", "%A", "%b", or
 "%B" specifier.  `gnuplot` will determine the proper month and weekday from the
 numerical values.  See `set format` for more details about these and other
 options for printing time data.  

 When reading two-digit years with %y, values 69-99 refer to the 20th century,
 while values 00-68 refer to the 21st century.   NB: This is in accordance with
 the UNIX98 spec, but conventions vary widely and two-digit year values are
 inherently ambiguous.

 See also `set xdata` and `time/date` for more information.

 Example:
       set timefmt "%d/%m/%Y\t%H:%M"
 tells `gnuplot` to read date and time separated by tab.  (But look closely at
 your data---what began as a tab may have been converted to spaces somewhere
 along the line; the format string must match what is actually in the file.)
 See also
 time data demo.
?commands set title
?commands show title
?set title
?show title
?title
 The `set title` command produces a plot title that is centered at the top of
 the plot.  `set title` is a special case of `set label`.

 Syntax:
       set title {"<title-text>"} {offset <offset>} {font "<font>{,<size>}"}
                 {{textcolor | tc} {<colorspec> | default}} {{no}enhanced}
       show title

 If <offset> is specified by either x,y or x,y,z the title is moved by the
 given offset.  It may be preceded by `first`, `second`, `graph`, `screen`,
 or `character` to select the coordinate system.  See `coordinates` for
 details.  By default, the `character` coordinate system is used.  For
 example, "`set title offset 0,-1`" will change only the y offset of the
 title, moving the title down by roughly the height of one character.  The
 size of a character depends on both the font and the terminal.

 <font> is used to specify the font with which the title is to be written;
 the units of the font <size> depend upon which terminal is used.

 `textcolor <colorspec>` changes the color of the text. <colorspec> can be a
 linetype, an rgb color, or a palette mapping. See help for `colorspec` and
 `palette`.

 `noenhanced` requests that the title not be processed by the enhanced text
 mode parser, even if enhanced text mode is currently active.

 `set title` with no parameters clears the title.

 See `syntax` for details about the processing of backslash sequences and
 the distinction between single- and double-quotes.
?commands set tmargin
?set tmargin
?tmargin
 The command `set tmargin` sets the size of the top margin.
 Please see `set margin` for details.
?commands set trange
?commands show trange
?set trange
?show trange
?trange
 The `set trange` command sets the parametric range used to compute x and y
 values when in parametric or polar modes.  Please see `set xrange` for
 details.
?commands set urange
?commands show urange
?set urange
?show urange
?urange
 The `set urange` and `set vrange` commands set the parametric ranges used
 to compute x, y, and z values when in `splot` parametric mode.
 Please see `set xrange` for details.
?commands show variables
?show variables all
?show variables
 The `show variables` command lists the current value of user-defined and
 internal variables. Gnuplot internally defines variables whose names begin
 with GPVAL_, MOUSE_, FIT_, and TERM_.

 Syntax:
       show variables      # show variables that do not begin with GPVAL_
       show variables all  # show all variables including those beginning GPVAL_
       show variables NAME # show only variables beginning with NAME

?show version
 The `show version` command lists the version of gnuplot being run, its last
 modification date, the copyright holders, and email addresses for the FAQ,
 the gnuplot-info mailing list, and reporting bugs--in short, the information
 listed on the screen when the program is invoked interactively.

 Syntax:
       show version {long}

 When the `long` option is given, it also lists the operating system, the
 compilation options used when `gnuplot` was installed, the location of the
 help file, and (again) the useful email addresses.
?commands set view
?commands show view
?set view
?set view map
?show view
?view
 The `set view` command sets the viewing angle for `splot`s.  It controls how
 the 3D coordinates of the plot are mapped into the 2D screen space.  It
 provides controls for both rotation and scaling of the plotted data, but
 supports orthographic projections only.  It supports both 3D projection or
 orthogonal 2D projection into a 2D plot-like map.

 Syntax:
       set view <rot_x>{,{<rot_z>}{,{<scale>}{,<scale_z>}}}
       set view map
       set view {no}equal {xy|xyz}
       show view

 where <rot_x> and <rot_z> control the rotation angles (in degrees) in a
 virtual 3D coordinate system aligned with the screen such that initially
 (that is, before the rotations are performed) the screen horizontal axis is
 x, screen vertical axis is y, and the axis perpendicular to the screen is z.
 The first rotation applied is <rot_x> around the x axis.  The second rotation
 applied is <rot_z> around the new z axis.

 Command `set view map` is used to represent the drawing as a map. It can be
 used for `contour` plots, or for color `pm3d` maps. In the latter, take care
 that you properly use `zrange` and `cbrange` for input data point filtering
 and color range scaling, respectively.

 <rot_x> is bounded to the [0:180] range with a default of 60 degrees, while
 <rot_z> is bounded to the [0:360] range with a default of 30 degrees.
 <scale> controls the scaling of the entire `splot`, while <scale_z> scales
 the z axis only.  Both scales default to 1.0.

 Examples:
       set view 60, 30, 1, 1
       set view ,,0.5

 The first sets all the four default values.  The second changes only scale,
 to 0.5.
?set view equal_axes
?set view equal
?view equal_axes
?view equal
?equal_axes
 The command `set view equal xy` forces the unit length of the x and y axes
 to be on the same scale, and chooses that scale so that the plot will fit on
 the page.  The command `set view equal xyz` additionally sets the z axis 
 scale to match the x and y axes; however there is no guarantee that the
 current z axis range will fit within the plot boundary.
 By default all three axes are scaled independently to fill the available area.

 See also `set xyplane`.
?commands set vrange
?commands show vrange
?set vrange
?show vrange
?vrange
 The `set urange` and `set vrange` commands set the parametric ranges used
 to compute x, y, and z values when in `splot` parametric mode.
 Please see `set xrange` for details.
?commands set x2data
?commands show x2data
?set x2data
?show x2data
?x2data
 The `set x2data` command sets data on the x2 (top) axis to timeseries
 (dates/times).  Please see `set xdata`.
?commands set x2dtics
?commands unset x2dtics
?commands show x2dtics
?set x2dtics
?unset x2dtics
?show x2dtics
?x2dtics
?nox2dtics
 The `set x2dtics` command changes tics on the x2 (top) axis to days of the
 week.  Please see `set xdtics` for details.
?commands set x2label
?commands show x2label
?set x2label
?show x2label
?x2label
 The `set x2label` command sets the label for the x2 (top) axis.
 Please see `set xlabel`.
?commands set x2mtics
?commands unset x2mtics
?commands show x2mtics
?set x2mtics
?unset x2mtics
?show x2mtics
?x2mtics
?nox2mtics
 The `set x2mtics` command changes tics on the x2 (top) axis to months of the
 year.  Please see `set xmtics` for details.
?commands set x2range
?commands show x2range
?set x2range
?show x2range
?x2range
 The `set x2range` command sets the horizontal range that will be displayed on
 the x2 (top) axis.  Please see `set xrange` for details.
?commands set x2tics
?commands unset x2tics
?commands show x2tics
?set x2tics
?unset x2tics
?show x2tics
?x2tics
?nox2tics
 The `set x2tics` command controls major (labelled) tics on the x2 (top) axis.
 Please see `set xtics` for details.
?commands set x2zeroaxis
?commands unset x2zeroaxis
?commands show x2zeroaxis
?set x2zeroaxis
?unset x2zeroaxis
?show x2zeroaxis
?x2zeroaxis
?nox2zeroaxis
 The `set x2zeroaxis` command draws a line at the origin of the x2 (top) axis
 (y2 = 0).  For details, please see `set zeroaxis`.
?commands set xdata
?commands show xdata
?set xdata
?show xdata
?xdata
 This command sets the datatype on the x axis to time/date.  A similar command
 does the same thing for each of the other axes.

 Syntax:
       set xdata {time}
       show xdata

 The same syntax applies to `ydata`, `zdata`, `x2data`, `y2data` and `cbdata`.

 The `time` option signals that the datatype is indeed time/date.  If the
 option is not specified, the datatype reverts to normal.

 See `set timefmt` to tell gnuplot how to read date or time data.  The
 time/date is converted to seconds from start of the century.  There is
 currently only one timefmt, which implies that all the time/date columns must
 conform to this format.  Specification of ranges should be supplied as quoted
 strings according to this format to avoid interpretation of the time/date as
 an expression.

 The function 'strftime' (type "man strftime" on unix to look it up) is used
 to print tic-mark labels.  `gnuplot` tries to figure out a reasonable format
 for this  unless the `set format x "string"` has supplied something that does
 not look like a decimal format (more than one '%' or neither %f nor %g).

 See also `time/date` for more information.
?commands set xdtics
?commands unset xdtics
?commands show xdtics
?set xdtics
?unset xdtics
?show xdtics
?xdtics
?noxdtics
 The `set xdtics` commands converts the x-axis tic marks to days of the week
 where 0=Sun and 6=Sat.  Overflows are converted modulo 7 to dates.  `set
 noxdtics` returns the labels to their default values.  Similar commands do
 the same things for the other axes.

 Syntax:
       set xdtics
       unset xdtics
       show xdtics

 The same syntax applies to `ydtics`, `zdtics`, `x2dtics`, `y2dtics` and
 `cbdtics`.

 See also the `set format` command.
?commands set xlabel
?commands show xlabel
?set xlabel
?show xlabel
?xlabel
 The `set xlabel` command sets the x axis label.  Similar commands set labels
 on the other axes.

 Syntax:
       set xlabel {"<label>"} {offset <offset>} {font "<font>{,<size>}"}
                  {textcolor <colorspec>} {{no}enhanced}
                  {rotate by <degrees> | rotate parallel | norotate}
       show xlabel

 The same syntax applies to `x2label`, `ylabel`, `y2label`, `zlabel` and
 `cblabel`.

 If <offset> is specified by either x,y or x,y,z the label is moved by the
 given offset.  It may be preceded by `first`, `second`, `graph`, `screen`,
 or `character` to select the coordinate system.  See `coordinates` for
 details.  By default, the `character` coordinate system is used.  For
 example, "`set xlabel offset -1,0`" will change only the x offset of the
 title, moving the label roughly one character width to the left.  The size
 of a character depends on both the font and the terminal.

 <font> is used to specify the font in which the label is written; the units
 of the font <size> depend upon which terminal is used.

 `noenhanced` requests that the label text not be processed by the enhanced text
 mode parser, even if enhanced text mode is currently active.

 To clear a label, put no options on the command line, e.g., "`set y2label`".

 The default positions of the axis labels are as follows:

 xlabel:  The x-axis label is centered below the bottom of the plot.

 ylabel:  The y-axis label is centered to the left of the plot, defaulting to
 either horizontal or vertical orientation depending on the terminal type.

 zlabel: The z-axis label is centered along the z axis and placed in the space
 above the grid level.

 cblabel: The color box axis label is centered along the box and placed below
 or to the right according to horizontal or vertical color box gradient.

 y2label: The y2-axis label is placed to the right of the y2 axis.  The
 position is terminal-dependent in the same manner as is the y-axis label.

 x2label: The x2-axis label is placed above the plot but below the title.
 It is also possible to create an x2-axis label by using new-line
 characters to make a multi-line plot title, e.g.,

       set title "This is the title\n\nThis is the x2label"

 Note that double quotes must be used.  The same font will be used for both
 lines, of course.

 The orientation (rotation angle) of the x, x2, y and y2 axis labels in 2D plots
 can be changed by specifying `rotate by <degrees>`.  The orientation of the x 
 and y axis labels in 3D plots defaults to horizontal but can be changed to run
 parallel to the axis by specifying `rotate parallel`.

 If you are not satisfied with the default position of an axis label, use `set
 label` instead--that command gives you much more control over where text is
 placed.

 Please see `syntax` for further information about backslash processing
 and the difference between single- and double-quoted strings.
?commands set xmtics
?commands unset xmtics
?commands show xmtics
?set xmtics
?unset xmtics
?show xmtics
?xmtics
?noxmtics
 The `set xmtics` command converts the x-axis tic marks to months of the
 year where 1=Jan and 12=Dec.  Overflows are converted modulo 12 to months.
 The tics are returned to their default labels by `unset xmtics`.  Similar
 commands perform the same duties for the other axes.

 Syntax:
       set xmtics
       unset xmtics
       show xmtics

 The same syntax applies to `x2mtics`, `ymtics`, `y2mtics`, `zmtics` and
 `cbmtics`.

 See also the `set format` command.
?commands set xrange
?commands show xrange
?set xrange
?show xrange
?writeback
?restore
?xrange
 The `set xrange` command sets the horizontal range that will be displayed.
 A similar command exists for each of the other axes, as well as for the
 polar radius r and the parametric variables t, u, and v.

 Syntax:
       set xrange { [{{<min>}:{<max>}}] {{no}reverse} {{no}writeback} }
                  | restore
       show xrange

 where <min> and <max> terms are constants, expressions or an asterisk to set
 autoscaling.  See below for full autoscaling syntax.  
 If the data are time/date, you must give the range as a quoted
 string according to the `set timefmt` format.  Any value omitted will not be
 changed.

 The same syntax applies to `yrange`, `zrange`, `x2range`, `y2range`, `cbrange`,
 `rrange`, `trange`, `urange` and `vrange`.

 The `reverse` option reverses the direction of the axis, e.g., `set xrange
 [0:1] reverse` will produce an axis with 1 on the left and 0 on the right.
 This is identical to the axis produced by `set xrange [1:0]`, of course.
 `reverse` is intended primarily for use with `autoscale`.

 Autoscaling:  If <min> (the same applies for correspondingly to <max>) is
 an asterisk "*" autoscaling is turned on.  The range in which autoscaling
 is being performed may be limited by a lower bound <lb> or an upper bound
 <ub> or both.  The syntax is 
       { <lb> < } * { < <ub> }
 For example,
       0 < * < 200
 sets <lb> = 0 and <ub> = 200.  With such a setting <min> would be autoscaled,
 but its final value will be between 0 and 200 (both inclusive despite the
 '<' sign).  If no lower or upper bound is specified, the '<' to also be
 ommited.  If <ub> is lower than <lb> the constraints will be turned off
 and full autoscaling will happen.
 This feature is useful to plot measured data with autoscaling but providing
 a limit on the range, to clip outliers, or to guarantee a minimum range
 that will be displayed even if the data would not need such a big range. 

 The `writeback` option essentially saves the range found by `autoscale` in
 the buffers that would be filled by `set xrange`.  This is useful if you wish
 to plot several functions together but have the range determined by only
 some of them.  The `writeback` operation is performed during the `plot`
 execution, so it must be specified before that command.  To restore,
 the last saved horizontal range use `set xrange restore`.  For example,

       set xrange [-10:10]
       set yrange [] writeback
       plot sin(x)
       set yrange restore
       replot x/2

 results in a yrange of [-1:1] as found only from the range of sin(x); the
 [-5:5] range of x/2 is ignored.  Executing `show yrange` after each command
 in the above example should help you understand what is going on.

 In 2D, `xrange` and `yrange` determine the extent of the axes, `trange`
 determines the range of the parametric variable in parametric mode or the
 range of the angle in polar mode.  Similarly in parametric 3D, `xrange`,
 `yrange`, and `zrange` govern the axes and `urange` and `vrange` govern the
 parametric variables.

 In polar mode, `rrange` determines the radial range plotted.  <rmin> acts as
 an additive constant to the radius, whereas <rmax> acts as a clip to the
 radius---no point with radius greater than <rmax> will be plotted.  `xrange`
 and `yrange` are affected---the ranges can be set as if the graph was of
 r(t)-rmin, with rmin added to all the labels.

 Any range may be partially or totally autoscaled, although it may not make
 sense to autoscale a parametric variable unless it is plotted with data.

 Ranges may also be specified on the `plot` command line.  A range given on
 the plot line will be used for that single `plot` command; a range given by
 a `set` command will be used for all subsequent plots that do not specify
 their own ranges.  The same holds true for `splot`.

 Examples:

 To set the xrange to the default:
       set xrange [-10:10]

 To set the yrange to increase downwards:
       set yrange [10:-10]

 To change zmax to 10 without affecting zmin (which may still be autoscaled):
       set zrange [:10]

 To autoscale xmin while leaving xmax unchanged:
       set xrange [*:]

 To autoscale xmin but keeping xmin positive:
       set xrange [0<*:]

 To autoscale x but keep minimum range of 10 to 50 (actual might be larger):
       set xrange [*<10:50<*]

 Autoscaling but limit maximum xrange to -1000 to 1000, i.e. autoscaling
 within [-1000:1000]
       set xrange [-1000<*:*<1000]

 Make sure xmin is somewhere between -200 and 100:
       set xrange [-200<*<100:]

?commands set xtics
?commands unset xtics
?commands show xtics
?set xtics
?unset xtics
?show xtics
?xtics
?noxtics
 Fine control of the major (labelled) tics on the x axis is possible with the
 `set xtics` command.  The tics may be turned off with the `unset xtics`
 command, and may be turned on (the default state) with `set xtics`.  Similar
 commands control the major tics on the y, z, x2 and y2 axes.

 Syntax:
       set xtics {axis | border} {{no}mirror}
                 {in | out} {scale {default | <major> {,<minor>}}}
                 {{no}rotate {by <ang>}} {offset <offset> | nooffset}
                 {left | right | center | autojustify}
                 {add}
                 {  autofreq
                  | <incr>
                  | <start>, <incr> {,<end>}
                  | ({"<label>"} <pos> {<level>} {,{"<label>"}...) }
                 { format "formatstring" } { font "name{,<size>}" }
                 { rangelimited }
                 { textcolor <colorspec> }
       unset xtics
       show xtics

 The same syntax applies to `ytics`, `ztics`, `x2tics`, `y2tics` and `cbtics`.

 `axis` or `border` tells `gnuplot` to put the tics (both the tics themselves
 and the accompanying labels) along the axis or the border, respectively.  If
 the axis is very close to the border, the `axis` option will move the
 tic labels to outside the border.  The relevant margin settings will usually
 be sized badly by the automatic layout algorithm in this case.

 `mirror` tells `gnuplot` to put unlabelled tics at the same positions on the
 opposite border.  `nomirror` does what you think it does.

 `in` and `out` change the tic marks to be drawn inwards or outwards.

 With `scale`, the size of the tic marks can be adjusted. If <minor> is not
 specified, it is 0.5*<major>.  The default size 1.0 for major tics and 0.5
 for minor tics is requested by `scale default`.

 `rotate` asks `gnuplot` to rotate the text through 90 degrees, which will be
 done if the terminal driver in use supports text rotation.  `norotate`
 cancels this. `rotate by <ang>` asks for rotation by <ang> degrees, supported
 by some terminal types.

 The defaults are `border mirror norotate` for tics on the x and y axes, and
 `border nomirror norotate` for tics on the x2 and y2 axes.  For the z axis,
 the `{axis | border}` option is not available and the default is
 `nomirror`.  If you do want to mirror the z-axis tics, you might want to
 create a bit more room for them with `set border`.

 The <offset> is specified by either x,y or x,y,z, and may be preceded by
 `first`, `second`, `graph`, `screen`, or `character` to select the
 coordinate system. <offset> is the offset of the tics texts from their
 default positions, while the default coordinate system is `character`.
 See `coordinates` for details. `nooffset` switches off the offset.

 Example:

 Move xtics more closely to the plot.
       set xtics offset 0,graph 0.05

 By default, tic labels are justified automatically depending on the axis and
 rotation angle to produce aesthetically pleasing results. If this is not
 desired, justification can be overridden with an explicit `left`, `right` or
 `center` keyword. `autojustify` restores the default behavior.

 `set xtics` with no options restores the default border or axis if xtics are
 being displayed;  otherwise it has no effect.  Any previously specified tic
 frequency or position {and labels} are retained.

 Positions of the tics are calculated automatically by default or if the
 `autofreq` option is given; otherwise they may be specified in either of
 two forms:

 The implicit <start>, <incr>, <end> form specifies that a series of tics will
 be plotted on the axis between the values <start> and <end> with an increment
 of <incr>.  If <end> is not given, it is assumed to be infinity.  The
 increment may be negative.  If neither <start> nor <end> is given, <start> is
 assumed to be negative infinity, <end> is assumed to be positive infinity,
 and the tics will be drawn at integral multiples of <incr>.  If the axis is
 logarithmic, the increment will be used as a multiplicative factor.

 If you specify to a negative <start> or <incr> after a numerical value
 (e.g., `rotate by <angle>` or `offset <offset>`), the parser fails because
 it subtracts <start> or <incr> from that value.  As a workaround, specify
 `0-<start>` resp. `0-<incr>` in that case.

 Example:
       set xtics border offset 0,0.5 -5,1,5
 Fails with 'invalid expression' at the last comma.
       set xtics border offset 0,0.5 0-5,1,5
 or
       set xtics offset 0,0.5 border -5,1,5
 Sets tics at the border, tics text with an offset of 0,0.5 characters, and
 sets the start, increment, and end to -5, 1, and 5, as requested.

 The `set grid` options 'front', 'back' and 'layerdefault' affect the drawing
 order of the xtics, too.

 Examples:

 Make tics at 0, 0.5, 1, 1.5, ..., 9.5, 10.
       set xtics 0,.5,10

 Make tics at ..., -10, -5, 0, 5, 10, ...
       set xtics 5

 Make tics at 1, 100, 1e4, 1e6, 1e8.
       set logscale x; set xtics 1,100,1e8

 The explicit ("<label>" <pos> <level>, ...) form allows arbitrary tic
 positions or non-numeric tic labels.  In this form, the tics do not
 need to be listed in numerical order.  Each tic has a
 position, optionally with a label.  Note that the label is
 a string enclosed by quotes.  It may be a constant string, such as
 "hello", may contain formatting information for converting the
 position into its label, such as "%3f clients", or may be empty, "".
 See `set format` for more information.  If no string is given, the
 default label (numerical) is used.

 An explicit tic mark has a third parameter, the "level".  The default
 is level 0, a major tic.  A level of 1 generates a minor tic.  If the
 level is specified, then the label must also be supplied.

 Examples:
       set xtics ("low" 0, "medium" 50, "high" 100)
       set xtics (1,2,4,8,16,32,64,128,256,512,1024)
       set ytics ("bottom" 0, "" 10, "top" 20)
       set ytics ("bottom" 0, "" 10 1, "top" 20)

 In the second example, all tics are labelled.  In the third, only the end
 tics are labelled.  In the fourth, the unlabeled tic is a minor tic.

 Normally if explicit tics are given, they are used instead of auto-generated
 tics. Conversely if you specify `set xtics auto` or the like it will erase
 any previously specified explicit tics. You can mix explicit and auto-
 generated tics by using the keyword `add`, which must appear before
 the tic style being added.

 Example:
       set xtics 0,.5,10
       set xtics add ("Pi" 3.14159)

 This will automatically generate tic marks every 0.5 along x, but will
 also add an explicit labeled tic mark at pi.

 However they are specified, tics will only be plotted when in range.

 Format (or omission) of the tic labels is controlled by `set format`, unless
 the explicit text of a label is included in the `set xtics ("<label>")` form.

 Minor (unlabelled) tics can be added automatically by the `set mxtics`
 command, or at explicit positions by the `set xtics ("" <pos> 1, ...)` form.
?set xtics time_axis tics
?xtics time_axis tics
?time_axis tics
 In case of timeseries data, axis tic position values must be given as quoted
 dates or times according to the format `timefmt`. If the <start>, <incr>, <end>
 form is used, <start> and <end> must be given according to `timefmt`, but
 <incr> must be in seconds.  Times will be written out according to the format
 given on `set format`, however.

 Examples:
       set xdata time
       set timefmt "%d/%m"
       set xtics format "%b %d"
       set xrange ["01/12":"06/12"]
       set xtics "01/12", 172800, "05/12"

       set xdata time
       set timefmt "%d/%m"
       set xtics format "%b %d"
       set xrange ["01/12":"06/12"]
       set xtics ("01/12", "" "03/12", "05/12")
 Both of these will produce tics "Dec 1", "Dec 3", and "Dec 5", but in the
 second example the tic at "Dec 3" will be unlabelled.
?set xtics rangelimited
?xtics rangelimited
?rangelimited
?range-frame
 This option limits both the auto-generated axis tic labels and the
 corresponding plot border to the range of values actually present in the data
 that has been plotted.  Note that this is independent of the current range 
 limits for the plot. For example, suppose that the data in "file.dat" all lies
 in the range 2 < y < 4.  Then the following commands will create a plot for
 which the left-hand plot border (y axis) is drawn for only this portion of the
 total y range, and only the axis tics in this region are generated.
 I.e., the plot will be scaled to the full range on y, but there will be a gap
 between 0 and 2 on the left border and another gap between 4 and 10. This
 style is sometimes referred to as a `range-frame` graph.
       set border 3
       set yrange [0:10]
       set ytics nomirror rangelimited
       plot "file.dat"
?commands set xyplane
?commands show xyplane
?set xyplane
?show xyplane
?xyplane
 The `set xyplane` command adjusts the position at which the xy plane is drawn
 in a 3D plot.  The synonym "set ticslevel" is accepted for backwards
 compatibility.

 Syntax:
       set xyplane at <zvalue>
       set xyplane relative <frac>
       set ticslevel <frac>        # equivalent to set xyplane relative
       show xyplane

 The form `set xyplane relative <frac>` places the xy plane below the range in
 Z, where the distance from the xy plane to Zmin is given as a fraction of the
 total range in z.  The default value is 0.5.  Negative values are permitted,
 but tic labels on the three axes may overlap.  The older, deprecated, form
 `set ticslevel` is retained for backwards compatibility.

 To place the xy-plane at a position 'pos' on the z-axis, `ticslevel` may
 be set equal to  (pos - zmin) / (zmin - zmax).  However, this position will
 change if the z range is changed.

 The alternative form `set xyplane at <zvalue>` fixes the placement of the
 xy plane at a specific Z value regardless of the current z range. Thus to
 force the x, y, and z axes to meet at a common origin one would specify
 `set xyplane at 0`.

 See also `set view`, and `set zeroaxis`.
?commands set xzeroaxis
?commands unset xzeroaxis
?commands show xzeroaxis
?set xzeroaxis
?unset xzeroaxis
?show xzeroaxis
?xzeroaxis
?noxzeroaxis
 The `set xzeroaxis` command draws a line at y = 0.  For details,
 please see `set zeroaxis`.
?commands set y2data
?commands show y2data
?set y2data
?show y2data
?y2data
 The `set y2data` command sets y2 (right-hand) axis data to timeseries
 (dates/times).  Please see `set xdata`.
?commands set y2dtics
?commands unset y2dtics
?set y2dtics
?unset y2dtics
?show y2dtics
?y2dtics
?noy2dtics
 The `set y2dtics` command changes tics on the y2 (right-hand) axis to days of
 the week.  Please see `set xdtics` for details.
?commands set y2label
?commands show y2label
?set y2label
?show y2label
?y2label
 The `set y2label` command sets the label for the y2 (right-hand) axis.
 Please see `set xlabel`.
?commands set y2mtics
?commands unset y2mtics
?commands show y2mtics
?set y2mtics
?unset y2mtics
?show y2mtics
?y2mtics
?noy2mtics
 The `set y2mtics` command changes tics on the y2 (right-hand) axis to months
 of the year.  Please see `set xmtics` for details.
?commands set y2range
?commands show y2range
?set y2range
?show y2range
?y2range
 The `set y2range` command sets the vertical range that will be displayed on
 the y2 (right-hand) axis.  Please see `set xrange` for details.
?commands set y2tics
?commands unset y2tics
?commands show y2tics
?set y2tics
?unset y2tics
?show y2tics
?y2tics
?noy2tics
 The `set y2tics` command controls major (labelled) tics on the y2 (right-hand)
 axis.  Please see `set xtics` for details.
?commands set y2zeroaxis
?commands unset y2zeroaxis
?commands show y2zeroaxis
?set y2zeroaxis
?unset y2zeroaxis
?show y2zeroaxis
?y2zeroaxis
?noy2zeroaxis
 The `set y2zeroaxis` command draws a line at the origin of the y2 (right-hand)
 axis (x2 = 0).  For details, please see `set zeroaxis`.
?commands set ydata
?commands show ydata
?set ydata
?show ydata
?ydata
 The `set ydata` commands sets y-axis data to timeseries (dates/times).
 Please see `set xdata`.
?commands set ydtics
?commands unset ydtics
?commands show ydtics
?set ydtics
?unset ydtics
?show ydtics
?ydtics
?noydtics
 The `set ydtics` command changes tics on the y axis to days of the week.
 Please see `set xdtics` for details.
?commands set ylabel
?commands show ylabel
?set ylabel
?show ylabel
?ylabel
 This command sets the label for the y axis.  Please see `set xlabel`.
?commands set ymtics
?commands unset ymtics
?commands show ymtics
?set ymtics
?unset ymtics
?show ymtics
?ymtics
?noymtics
 The `set ymtics` command changes tics on the y axis to months of the year.
 Please see `set xmtics` for details.
?commands set yrange
?commands show yrange
?set yrange
?show yrange
?yrange
 The `set yrange` command sets the vertical range that will be displayed on
 the y axis.  Please see `set xrange` for details.
?commands set ytics
?commands unset ytics
?commands show ytics
?set ytics
?unset ytics
?show ytics
?ytics
?noytics
 The `set ytics` command controls major (labelled) tics on the y axis.
 Please see `set xtics` for details.
?commands set yzeroaxis
?commands unset yzeroaxis
?commands show yzeroaxis
?set yzeroaxis
?unset yzeroaxis
?show yzeroaxis
?yzeroaxis
?noyzeroaxis
 The `set yzeroaxis` command draws a line at x = 0.  For details,
 please see `set zeroaxis`.
?commands set zdata
?commands show zdata
?set zdata
?show zdata
?zdata
 The `set zdata` command sets zaxis data to timeseries (dates/times).
 Please see `set xdata`.
?commands set zdtics
?commands unset zdtics
?commands show zdtics
?set zdtics
?unset zdtics
?show zdtics
?zdtics
?nozdtics
 The `set zdtics` command changes tics on the z axis to days of the week.
 Please see `set xdtics` for details.
?commands set zzeroaxis
?commands unset zzeroaxis
?commands show zzeroaxis
?set zzeroaxis
?unset zzeroaxis
?show zzeroaxis
?zzeroaxis
?nozzeroaxis
 The `set zzeroaxis` command draws a line through (x=0,y=0).  This has no effect
 on 2D plots, including splot with `set view map`. For details, please
 see `set zeroaxis` and `set xyplane`.
?commands set cbdata
?commands show cbdata
?set cbdata
?show cbdata
?cbdata
 Set color box axis data to timeseries (dates/times).  Please see `set xdata`.
?commands set cbdtics
?commands unset cbdtics
?commands show cbdtics
?set cbdtics
?unset cbdtics
?show cbdtics
?cbdtics
?nocbdtics
 The `set cbdtics` command changes tics on the color box axis to days of the
 week. Please see `set xdtics` for details.
?commands set zero
?commands show zero
?set zero
?show zero
?zero
 The `zero` value is the default threshold for values approaching 0.0.

 Syntax:
       set zero <expression>
       show zero

 `gnuplot` will not plot a point if its imaginary part is greater in magnitude
 than the `zero` threshold.  This threshold is also used in various other
 parts of `gnuplot` as a (crude) numerical-error threshold.  The default
 `zero` value is 1e-8.  `zero` values larger than 1e-3 (the reciprocal of the
 number of pixels in a typical bitmap display) should probably be avoided, but
 it is not unreasonable to set `zero` to 0.0.
?commands set zeroaxis
?commands unset zeroaxis
?commands show zeroaxis
?set zeroaxis
?unset zeroaxis
?show zeroaxis
?zeroaxis
 The x axis may be drawn by `set xzeroaxis` and removed by `unset xzeroaxis`.
 Similar commands behave similarly for the y, x2, y2, and z axes.

 Syntax:
       set {x|x2|y|y2|z}zeroaxis { {linestyle | ls <line_style>}
                                  | { linetype | lt <line_type>}
                                    { linewidth | lw <line_width>}}
       unset {x|x2|y|y2|z}zeroaxis
       show {x|y|z}zeroaxis


 By default, these options are off.  The selected zero axis is drawn
 with a line of type <line_type> and width <line_width> (if supported
 by the terminal driver currently in use), or a user-defined style
 <line_style>.

 If no linetype is specified, any zero axes selected will be drawn
 using the axis linetype (linetype 0).

 `set zeroaxis` is equivalent to `set xzeroaxis; set yzeroaxis`.
 Note that the z-axis must be set separately using `set zzeroaxis`.

 Examples:

 To simply have the y=0 axis drawn visibly:

        set xzeroaxis

 If you want a thick line in a different color or pattern, instead:

        set xzeroaxis linetype 3 linewidth 2.5
?commands set zlabel
?commands show zlabel
?set zlabel
?show zlabel
?zlabel
 This command sets the label for the z axis.  Please see `set xlabel`.
?commands set zmtics
?commands unset zmtics
?commands show zmtics
?set zmtics
?unset zmtics
?show zmtics
?zmtics
?nozmtics
 The `set zmtics` command changes tics on the z axis to months of the year.
 Please see `set xmtics` for details.
?commands set zrange
?commands show zrange
?set zrange
?show zrange
?zrange
 The `set zrange` command sets the range that will be displayed on the z axis.
 The zrange is used only by `splot` and is ignored by `plot`.  Please see
 `set xrange` for details.
?commands set ztics
?commands unset ztics
?commands show ztics
?set ztics
?unset ztics
?show ztics
?ztics
?noztics
 The `set ztics` command controls major (labelled) tics on the z axis.
 Please see `set xtics` for details.
?commands set cblabel
?commands show cblabel
?set cblabel
?show cblabel
?cblabel
 This command sets the label for the color box axis.  Please see `set xlabel`.
?commands set cbmtics
?commands unset cbmtics
?commands show cbmtics
?set cbmtics
?unset cbmtics
?show cbmtics
?cbmtics
?nocbmtics
 The `set cbmtics` command changes tics on the color box axis to months of the
 year. Please see `set xmtics` for details.
?commands set cbrange
?commands show cbrange
?set cbrange
?show cbrange
?cbrange
 The `set cbrange` command sets the range of values which are colored using
 the current `palette` by styles `with pm3d`, `with image` and `with palette`.
 Values outside of the color range use color of the nearest extreme.

 If the cb-axis is autoscaled in `splot`, then the colorbox range is taken from
 `zrange`.  Points drawn in `splot ... pm3d|palette` can be filtered by using
 different `zrange` and `cbrange`.

 Please see `set xrange` for details on `set cbrange` syntax. See also
 `set palette` and `set colorbox`.
?commands set cbtics
?commands unset cbtics
?commands show cbtics
?set cbtics
?unset cbtics
?show cbtics
?cbtics
?nocbtics
 The `set cbtics` command controls major (labelled) tics on the color box axis.
 Please see `set xtics` for details.
?commands shell
?shell
 The `shell` command spawns an interactive shell.  To return to `gnuplot`,
 type `logout` if using VMS, `exit` or the END-OF-FILE character if using
 Unix, or `exit` if using MS-DOS or OS/2.

 There are two ways of spawning a shell command: using `system` command
 or via `!` ($ if using VMS). The former command takes a string as a
 parameter and thus it can be used anywhere among other gnuplot commands,
 while the latter syntax requires to be the only command on the line. Control
 will return immediately to `gnuplot` after this command is executed.  For
 example, in MS-DOS or OS/2,

       ! dir
 or
       system "dir"

 prints a directory listing and then returns to `gnuplot`.

 Other examples of the former syntax:
        system "date"; set time; plot "a.dat"
        print=1; if (print) replot; set out; system "lpr x.ps"
?commands splot
?splot
 `splot` is the command for drawing 3D plots (well, actually projections on
 a 2D surface, but you knew that).  It can create a plot from functions or
 data read from files in a manner very similar to the `plot` command.
 `splot` provides only a single x, y, and z axis; there is no equivalent to the
 x2 and y2 secondary axes provided by `plot`.

 See the `plot` command for many options available in both 2D and 3D plots.

 Syntax:
       splot {<ranges>}
             {<iteration>}
             <function> | "<datafile>" {datafile-modifiers}}
             {<title-spec>} {with <style>}
             {, {definitions{,}} <function> ...}

 where either a <function> or the name of a data file enclosed in quotes is
 supplied.  The function can be a mathematical expression, or a triple of
 mathematical expressions in parametric mode.

 By default `splot` draws the xy plane completely below the plotted data.
 The offset between the lowest ztic and the xy plane can be changed by `set
 xyplane`.  The orientation of a `splot` projection is controlled by
 `set view`.  See `set view` and `set xyplane` for more information.

 The syntax for setting ranges on the `splot` command is the same as for
 `plot`.  In non-parametric mode, the order in which ranges must be given is
 `xrange`, `yrange`, and `zrange`.  In parametric mode, the order is `urange`,
 `vrange`, `xrange`, `yrange`, and `zrange`.

 The `title` option is the same as in `plot`.  The operation of `with` is also
 the same as in `plot`, except that the plotting styles available to `splot`
 are limited to `lines`, `points`, `linespoints`, `dots`, and `impulses`;  the
 error-bar capabilities of `plot` are not available for `splot`.

 The `datafile` options have more differences.

 See also `show plot`.
?commands splot datafile
?splot datafile
 `Splot`, like `plot`, can display from a file.

 Syntax:
       splot '<file_name>' {binary <binary list>}
                           {{nonuniform} matrix}
                           {index <index list>}
                           {every <every list>}
                           {using <using list>}

 The special filenames `""` and `"-"` are permitted, as in `plot`.
 See `special-filenames`.

 In brief, `binary` and `matrix` indicate that the data are in a special
 form, `index` selects which data sets in a multi-data-set file are to be
 plotted, `every` specifies which datalines (subsets) within a single data
 set are to be plotted, and `using` determines how the columns within a single
 record are to be interpreted.

 The options `index` and `every` behave the same way as with `plot`;  `using`
 does so also, except that the `using` list must provide three entries
 instead of two.

 The `plot` options `thru` and `smooth` are not available for `splot`, but
 `cntrparam` and `dgrid3d` provide limited smoothing capabilities.

 Data file organization is essentially the same as for `plot`, except that
 each point is an (x,y,z) triple.  If only a single value is provided, it
 will be used for z, the datablock number will be used for y, and the index
 of the data point in the datablock will be used for x.  If two or four values
 are provided, `gnuplot` uses the last value for calculating the color in
 pm3d plots.  Three values are interpreted as an (x,y,z) triple.  Additional
 values are generally used as errors, which can be used by `fit`.

 Single blank records separate datablocks in a `splot` datafile; `splot`
 treats datablocks as the equivalent of function y-isolines.  No line will
 join points separated by a blank record.  If all datablocks contain the same
 number of points, `gnuplot` will draw cross-isolines between datablocks,
 connecting corresponding points.  This is termed "grid data", and is required
 for drawing a surface, for contouring (`set contour`) and hidden-line removal
 (`set hidden3d`). See also `splot grid_data`.

 It is no longer necessary to specify `parametric` mode for three-column
 `splot`s.
?commands plot datafile matrix
?commands splot datafile matrix
?plot datafile matrix binary
?splot datafile matrix binary
?plot binary matrix
?splot binary matrix
?plot matrix binary
?splot matrix binary
?matrix binary
?binary matrix
 Gnuplot can interpret matrix input in two different ways.
 The first of these assumes a uniform grid of x and y coordinates, and assigns
 each value in the input matrix to one element of this uniform grid.
 This is the default for ascii data input, but not for binary input.
 Example commands for plotting uniform matrix data:
      splot 'file' matrix using 1:2:3          # ascii input
      splot 'file' binary general using 1:2:3  # binary input

 In a uniform grid matrix the z-values are read in a row at a time, i. e.,
     z11 z12 z13 z14 ...
     z21 z22 z23 z24 ...
     z31 z32 z33 z34 ...
 and so forth.

 For ascii input, a blank line or comment line ends the matrix, and starts a new
 surface mesh.  You can select among the meshes inside a file by the `index`
 option to the `splot` command, as usual. 
 The second interpretation assumes a non-uniform grid with explicit x and y
 coordinates. The first row of input data contains the y coordinates; 
 the first column of input data contains the x coordinates.  For binary input
 data, the first element of the first row must contain the number of data
 columns. (This number is ignored for ascii input).  Both the coordinates and
 the data values in a binary input are treated as single precision floats.
 Example commands for plotting non-uniform matrix data:
      splot 'file' nonuniform matrix using 1:2:3  # ascii input
      splot 'file' binary matrix using 1:2:3      # binary input

 Thus the data organization for non-uniform matrix input is

       <N+1>  <y0>   <y1>   <y2>  ...  <yN>
        <x0> <z0,0> <z0,1> <z0,2> ... <z0,N>
        <x1> <z1,0> <z1,1> <z1,2> ... <z1,N>
         :      :      :      :   ...    :

 which is then converted into triplets:
       <x0> <y0> <z0,0>
       <x0> <y1> <z0,1>
       <x0> <y2> <z0,2>
        :    :     :
       <x0> <yN> <z0,N>

       <x1> <y0> <z1,0>
       <x1> <y1> <z1,1>
        :    :     :

 These triplets are then converted into `gnuplot` iso-curves and then
 `gnuplot` proceeds in the usual manner to do the rest of the plotting.

 A collection of matrix and vector manipulation routines (in C) is provided
 in `binary.c`.  The routine to write binary data is

       int fwrite_matrix(file,m,nrl,nrl,ncl,nch,row_title,column_title)

 An example of using these routines is provided in the file `bf_test.c`, which
 generates binary files for the demo file `demo/binary.dem`.

 Usage in `plot`:
     plot `a.dat` matrix
     plot `a.dat` matrix using 1:3
     plot 'a.gpbin' {matrix} binary using 1:3
 will plot rows of the matrix, while using 2:3 will plot matrix columns, and
 using 1:2 the point coordinates (rather useless). Applying the `every` option
 you can specify explicit rows and columns.

 Example -- rescale axes of a matrix in an ascii file:
     splot `a.dat` matrix using (1+$1):(1+$2*10):3

 Example -- plot the 3rd row of a matrix in an ascii file:
     plot 'a.dat' matrix using 1:3 every 1:999:1:2
 (rows are enumerated from 0, thus 2 instead of 3).

 Gnuplot can read matrix binary files by use of the option `binary` appearing
 without keyword qualifications unique to general binary, i.e., `array`,
 `record`, `format`, or `filetype`.  Other general binary keywords for
 translation should also apply to matrix binary.  (See `binary general` for
 more details.)
?commands splot datafile example
?splot datafile example
?splot example
 A simple example of plotting a 3D data file is

       splot 'datafile.dat'

 where the file "datafile.dat" might contain:

       # The valley of the Gnu.
          0 0 10
          0 1 10
          0 2 10

          1 0 10
          1 1 5
          1 2 10

          2 0 10
          2 1 1
          2 2 10

          3 0 10
          3 1 0
          3 2 10

 Note that "datafile.dat" defines a 4 by 3 grid ( 4 rows of 3 points each ).
 Rows (datablocks) are separated by blank records.

 Note also that the x value is held constant within each dataline.  If you
 instead keep y constant, and plot with hidden-line removal enabled, you will
 find that the surface is drawn 'inside-out'.

 Actually for grid data it is not necessary to keep the x values constant
 within a datablock, nor is it necessary to keep the same sequence of y
 values.  `gnuplot` requires only that the number of points be the same for
 each datablock.  However since the surface mesh, from which contours are
 derived, connects sequentially corresponding points, the effect of an
 irregular grid on a surface plot is unpredictable and should be examined
 on a case-by-case basis.
?commands splot grid_data
?splot grid_data
?grid_data
 The 3D routines are designed for points in a grid format, with one sample,
 datapoint, at each mesh intersection; the datapoints may originate from
 either evaluating a function, see `set isosamples`, or reading a datafile,
 see `splot datafile`.  The term "isoline" is applied to the mesh lines for
 both functions and data.  Note that the mesh need not be rectangular in x
 and y, as it may be parameterized in u and v, see `set isosamples`.

 However, `gnuplot` does not require that format.  In the case of functions,
 'samples' need not be equal to 'isosamples', i.e., not every x-isoline
 sample need intersect a y-isoline. In the case of data files, if there
 are an equal number of scattered data points in each datablock, then
 "isolines" will connect the points in a datablock, and "cross-isolines"
 will connect the corresponding points in each datablock to generate a
 "surface".  In either case, contour and hidden3d modes may give different
 plots than if the points were in the intended format.  Scattered data can be
 converted to a {different} grid format with `set dgrid3d`.

 The contour code tests for z intensity along a line between a point on a
 y-isoline and the corresponding point in the next y-isoline.  Thus a `splot`
 contour of a surface with samples on the x-isolines that do not coincide with
 a y-isoline intersection will ignore such samples. Try:
        set xrange [-pi/2:pi/2]; set yrange [-pi/2:pi/2]
        set style function lp
        set contour
        set isosamples 10,10; set samples 10,10;
        splot cos(x)*cos(y)
        set samples 4,10; replot
        set samples 10,4; replot

?commands splot surfaces
?splot surfaces
 `splot` can display a surface as a collection of points, or by connecting
 those points.  As with `plot`, the points may be read from a data file or
 result from evaluation of a function at specified intervals, see
 `set isosamples`.  The surface may be approximated by connecting the points
 with straight line segments, see `set surface`, in which case the surface
 can be made opaque with `set hidden3d.`  The orientation from which the 3d
 surface is viewed can be changed with `set view`.

 Additionally, for points in a grid format, `splot` can interpolate points
 having a common amplitude (see `set contour`) and can then connect those
 new points to display contour lines, either directly with straight-line
 segments or smoothed lines (see `set cntrparam`).  Functions are already
 evaluated in a grid format, determined by `set isosamples` and `set samples`,
 while file data must either be in a grid format, as described in `data-file`,
 or be used to generate a grid (see `set dgrid3d`).

 Contour lines may be displayed either on the surface or projected onto the
 base.  The base projections of the contour lines may be written to a
 file, and then read with `plot`, to take advantage of `plot`'s additional
 formatting capabilities.
?commands stats
?stats
?statistics
 Syntax:
      stats 'filename' [using N[:M]] [name 'prefix'] [[no]output]]
 This command prepares a statistical summary of the data in one or two columns
 of a file. The using specifier is interpreted in the same way as for plot
 commands. See `plot` for details on the `index`, `every`, and `using`
 directives. Data points are filtered against both xrange and yrange before
 analysis. See `set xrange`. The summary is printed to the screen by default.
 Output can be redirected to a file by prior use of the command `set print`,
 or suppressed altogether using the `nooutput` option.  
 
 In addition to printed output, the program stores the individual statistics
 into three sets of variables.
 The first set of variables reports how the data is laid out in the file:
      STATS_records           # total number of in-range data records
      STATS_outofrange        # number of records filtered out by range limits
      STATS_invalid           # number of invalid/incomplete/missing records
      STATS_blank             # number of blank lines in the file
      STATS_blocks            # number of indexable data blocks in the file

 The second set reports properties of the in-range data from a single column.
 If the corresponding axis is autoscaled (x-axis for the 1st column, y-axis 
 for the optional second column) then no range limits are applied. If two
 columns are being analysed in a single `stats` command, the the suffix "_x"
 or "_y" is appended to each variable name.  I.e. STATS_min_x is the minimum
 value found in the first column, while STATS_min_y is the minimum value found
 in the second column.
      STATS_min               # minimum value of in-range data points
      STATS_max               # maximum value of in-range data points
      STATS_index_min         # index i for which data[i] == STATS_min
      STATS_index_max         # index i for which data[i] == STATS_max
      STATS_lo_quartile       # value of the lower (1st) quartile boundary
      STATS_median            # median value
      STATS_up_quartile       # value of the upper (3rd) quartile boundary
      STATS_mean              # mean value of in-range data points
      STATS_stddev            # standard deviation of the in-range data points
      STATS_sum               # sum
      STATS_sumsq             # sum of squares

 The third set of variables is only relevant to analysis of two data columns.
      STATS_correlation       # correlation coefficient between x and y values
      STATS_slope             # A corresponding to a linear fit y = Ax + B
      STATS_intercept         # B corresponding to a linear fit y = Ax + B
      STATS_sumxy             # sum of x*y
      STATS_pos_min_y         # x coordinate of a point with minimum y value
      STATS_pos_max_y         # x coordinate of a point with maximum y value
 
 It may be convenient to track the statistics from more than one file at the
 same time. The `name` option causes the default prefix "STATS" to be replaced
 by a user-specified string.  For example, the mean value of column 2 data from
 two different files could be compared by
      stats "file1.dat" using 2 name "A"
      stats "file2.dat" using 2 name "B"
      if (A_mean < B_mean) {...}

 The index reported in STATS_index_xxx corresponds to the value of pseudo-column
 0 ($0) in plot commands.  I.e. the first point has index 0, the last point
 has index N-1.

 Data values are sorted to find the median and quartile boundaries.
 If the total number of points N is odd, then the median value is taken as the
 value of data point (N+1)/2. If N is even, then the median is reported as the
 mean value of points N/2 and (N+2)/2. Equivalent treatment is used for the
 quartile boundaries.

 For an example of using the `stats` command to help annotate a subsequent plot,
 see
 stats.dem.

 The current implementation does not allow analysis if either the X or Y axis is
 set to log-scaling.  This restriction may be removed in a later version.

?commands system
?system
 `system "command"` executes "command" using the standard shell. See `shell`.
 If called as a function, `system("command")` returns the resulting character
 stream from stdout as a string.  One optional trailing newline is ignored.

 This can be used to import external functions into gnuplot scripts:

       f(x) = real(system(sprintf("somecommand %f", x)))
?commands test
?test palette
?test
 This command graphically tests or presents terminal and palette capabilities.

 Syntax:
       test {terminal | palette [rgb|rbg|grb|gbr|brg|bgr]}

 `test` or `test terminal` creates a display of line and point styles and other
 useful things appropriate for and supported by the `terminal` you are just
 using.

 `test palette` plots profiles of R(z),G(z),B(z), where 0<=z<=1. These are the
 RGB components of the current color `palette`. It also plots the apparent net
 intensity as calculated using NTSC coefficients to map RGB onto a grayscale.
 The optional parameter, a permutation of letters rgb, determines the sequence in
 which the r,g,b profiles are drawn.
?commands undefine
?undefine
 Clear one or more previously defined user variables.  This is useful in order
 to reset the state of a script containing an initialization test. 

 A variable name can contain the wildcard character `*` as last character. If the
 wildcard character is found, all variables with names that begin with the prefix 
 preceding the wildcard will be removed. This is useful to remove several variables 
 sharing a common prefix. Note that the wildcard character is only allowed at the 
 end of the variable name! Specifying the wildcard character as sole argument to 
 `undefine` has no effect.

 Example:

       undefine foo foo1 foo2
       if (!exists("foo")) load "initialize.gp"

       bar = 1; bar1 = 2; bar2 = 3
       undefine bar*                 # removes all three variables

?commands unset
?unset
 Options set using the `set` command may be returned to their default state by
 the corresponding `unset` command.  The `unset` command may contain an optional
 iteration clause. See `iteration`.

 Examples:
       set xtics mirror rotate by -45 0,10,100
       ...
       unset xtics

       # Unset labels numbered between 100 and 200
       unset for [i=100:200] label i
?unset terminal
 The default terminal that is active at the time of program entry depends on the
 system platform, gnuplot build options, and the environmental variable GNUTERM.
 Whatever this default may be, gnuplot saves it in the internal variable GNUTERM.
 The `unset terminal` command restores this initial state.  It is equivalent to
 `set terminal GNUTERM`.
?commands update
?update
 This command writes the current values of the fit parameters into the given
 file, formatted as an initial-value file (as described in the `fit`section).
 This is useful for saving the current values for later use or for restarting
 a converged or stopped fit.

 Syntax:
       update <filename> {<filename>}

 If a second filename is supplied, the updated values are written to this
 file, and the original parameter file is left unmodified.

 Otherwise, if the file already exists, `gnuplot` first renames it by
 appending `.old` and then opens a new file.  That is, "`update 'fred'`"
 behaves the same as "`!rename fred fred.old; update 'fred.old' 'fred'`".
 [On DOS and other systems that use the twelve-character "filename.ext"
 naming convention, "ext" will be "`old`" and "filename" will be related
 (hopefully recognizably) to the initial name.  Renaming is not done at all
 on VMS systems, since they use file-versioning.]

 Please see `fit` for more information.
?while
?commands while
 Syntax:
       while (<expr>) {
           <commands>
       }
 Execute a block of commands repeatedly so long as <expr> evaluates to 
 a non-zero value.  This command cannot be mixed with old-style (un-bracketed)
 if/else statements.  See `if`.
?complete list of terminals
?terminal
?term
 Gnuplot supports a large number of output formats. These are selected by
 choosing an appropriate terminal type, possibly with additional modifying
 options. See `set terminal`.

 This document may describe terminal types that are not available to you
 because they were not configured or installed on your system. To see a list of
 terminals available on a particular gnuplot installation, type 'set terminal'
 with no modifiers.
?commands set terminal gpic
?set terminal gpic
?set term gpic
?terminal gpic
?term gpic
?gpic
 The `gpic` terminal driver generates GPIC graphs in the Free Software
 Foundations's "groff" package.  The default size is 5 x 3 inches.  The only
 option is the origin, which defaults to (0,0).

 Syntax:
       set terminal gpic {<x> <y>}

 where `x` and `y` are in inches.

 A simple graph can be formatted using

       groff -p -mpic -Tps file.pic > file.ps.

 The output from pic can be pipe-lined into eqn, so it is possible to put
 complex functions in a graph with the `set label` and `set {x/y}label`
 commands.  For instance,

       set ylab '@space 0 int from 0 to x alpha ( t ) roman d t@'

 will label the y axis with a nice integral if formatted with the command:

       gpic filename.pic | geqn -d@@ -Tps | groff -m[macro-package] -Tps
           > filename.ps

 Figures made this way can be scaled to fit into a document.  The pic language
 is easy to understand, so the graphs can be edited by hand if need be.  All
 co-ordinates in the pic-file produced by `gnuplot` are given as x+gnuplotx
 and y+gnuploty.  By default x and y are given the value 0.  If this line is
 removed with an editor in a number of files, one can put several graphs in
 one figure like this (default size is 5.0x3.0 inches):

       .PS 8.0
       x=0;y=3
       copy "figa.pic"
       x=5;y=3
       copy "figb.pic"
       x=0;y=0
       copy "figc.pic"
       x=5;y=0
       copy "figd.pic"
       .PE

 This will produce an 8-inch-wide figure with four graphs in two rows on top
 of each other.

 One can also achieve the same thing by the command

       set terminal gpic x y

 for example, using

       .PS 6.0
       copy "trig.pic"
       .PE
?commands set terminal regis
?set terminal regis
?set term regis
?terminal regis
?term regis
?regis
 The `regis` terminal device generates output in the REGIS graphics language.
 It has the option of using 4 (the default) or 16 colors.

 Syntax:
       set terminal regis {4 | 16}
?commands set terminal tek410x
?set terminal tek410x
?set term tek410x
?terminal tek410x
?term tek410x
?tek410x
 The `tek410x` terminal driver supports the 410x and 420x family of Tektronix
 terminals.  It has no options.
?commands set terminal tek40xx
?set terminal tek40xx
?set term tek40xx
?terminal tek40xx
?term tek40xx
?tek40
?commands set terminal vttek
?set terminal vttek
?set term vttek
?terminal vttek
?term vttek
?vttek
?commands set terminal xterm
?set terminal xterm
?set term xterm
?terminal xterm
?term xterm
?xterm
 This family of terminal drivers supports a variety of VT-like terminals.
 `tek40xx` supports Tektronix 4010 and others as well as most TEK emulators.
 `vttek` supports VT-like tek40xx terminal emulators.
 The following are present only if selected when gnuplot is built:
 `kc-tek40xx` supports MS-DOS Kermit Tek4010 terminal emulators in color;
 `km-tek40xx` supports them in monochrome. `selanar` supports Selanar graphics.
 `bitgraph` supports BBN Bitgraph terminals.
 None have any options.
?commands set terminal x11
?set terminal x11
?set term x11
?terminal x11
?term x11
?x11
?X11

 Syntax:
    set terminal x11 {<n> | window "<string>"}
                     {title "<string>"}
                     {{no}enhanced} {font <fontspec>}
                     {linewidth LW} {solid|dashed}
                     {{no}persist} {{no}raise} {{no}ctrlq}
                     {close}
                     {size XX,YY} {position XX,YY}
    set terminal x11 {reset}

 Multiple plot windows are supported: `set terminal x11 <n>` directs the
 output to plot window number n.  If n is not 0, the terminal number will be
 appended to the window title (unless a title has been supplied manually)
 and the icon will be labeled `Gnuplot <n>`.  The active window may be
 distinguished by a change in cursor (from default to crosshair).

 The `x11` terminal can connect to X windows previously created by an outside
 application via the option `window` followed by a string containing the
 X ID for the window in hexadecimal format.  Gnuplot uses that external X
 window as a container since X does not allow for multiple clients selecting
 the ButtonPress event.  In this way, gnuplot's mouse features work within
 the contained plot window.

    set term x11 window "220001e"

 The x11 terminal supports enhanced text mode (see `enhanced`), subject
 to the available fonts. In order for font size commands embedded in text
 to have any effect, the default x11 font must be scalable. Thus the first
 example below will work as expected, but the second will not.

    set term x11 enhanced font "arial,15" 
    set title '{/=20 Big} Medium {/=5 Small}' 

    set term x11 enhanced font "terminal-14" 
    set title '{/=20 Big} Medium {/=5 Small}' 

 Plot windows remain open even when the `gnuplot` driver is changed to a
 different device.  A plot window can be closed by pressing the letter q
 while that window has input focus, or by choosing `close` from a window
 manager menu.  All plot windows can be closed by specifying `reset`, which
 actually terminates the subprocess which maintains the windows (unless
 `-persist` was specified).  The `close` command can be used to close
 individual plot windows by number.  However, after a `reset`, those plot
 windows left due to persist cannot be closed with the command `close`.
 A `close` without a number closes the current active plot window.

 The gnuplot outboard driver, gnuplot_x11, is searched in a default place
 chosen when the program is compiled.  You can override that by defining
 the environment variable GNUPLOT_DRIVER_DIR to point to a different
 location.

 Plot windows will automatically be closed at the end of the session
 unless the `-persist` option was given.

 The options `persist` and `raise` are unset by default, which means that
 the defaults (persist == no and raise == yes) or the command line options
 -persist / -raise or the Xresources are taken.  If [no]persist or
 [no]raise are specified, they will override command line options and
 Xresources.  Setting one of these options takes place immediately, so
 the behaviour of an already running driver can be modified.  If the window
 does not get raised, see discussion in `raise`.

 The option `title "<title name>"` will supply the title name of the window
 for the current plot window or plot window <n> if a number is given.
 Where (or if) this title is shown depends on your X window manager.

 The size option can be used to set the size of the plot window.  The
 size option will only apply to newly created windows.

 The position option can be used to set the position of the plot window.  The
 position option will only apply to newly created windows.

 The size or aspect ratio of a plot may be changed by resizing the `gnuplot`
 window.

 Linewidths and pointsizes may be changed from within `gnuplot` with
 `set linestyle`.

 For terminal type `x11`, `gnuplot` accepts (when initialized) the standard
 X Toolkit options and resources such as geometry, font, and name from the
 command line arguments or a configuration file.  See the X(1) man page
 (or its equivalent) for a description of such options.

 A number of other `gnuplot` options are available for the `x11` terminal.
 These may be specified either as command-line options when `gnuplot` is
 invoked or as resources in the configuration file ".Xdefaults".  They are
 set upon initialization and cannot be altered during a `gnuplot` session.
 (except `persist` and `raise`)
?commands set terminal x11 x11_fonts
?set terminal x11 x11_fonts
?set term x11 x11_fonts
?x11 x11_fonts
?x11_fonts
 Upon initial startup, the default font is taken from the X11 resources
 as set in the system or user .Xdefaults file or on the command line.

 Example:
       gnuplot*font: lucidasans-bold-12
 A new default font may be specified to the x11 driver from inside
 gnuplot using
      `set term x11 font "<fontspec>"`
 The driver first queries the X-server for a font of the exact name given.
 If this query fails, then it tries to interpret <fontspec> as
 "<font>,<size>,<slant>,<weight>" and to construct a full X11 font name
 of the form
       -*-<font>-<weight>-<s>-*-*-<size>-*-*-*-*-*-<encoding>

  <font> is the base name of the font (e.g. Times or Symbol)
  <size> is the point size (defaults to 12 if not specified)
  <s> is `i` if <slant>=="italic" `o` if <slant>=="oblique" `r` otherwise
  <weight> is `medium` or `bold` if explicitly requested, otherwise `*`
  <encoding> is set based on the current character set (see `set encoding`).
 So `set term x11 font "arial,15,italic"` will be translated to
 -*-arial-*-i-*-*-15-*-*-*-*-*-iso8859-1 (assuming default encoding).
 The <size>, <slant>, and <weight> specifications are all optional.
 If you do not specify <slant> or <weight> then you will get whatever font 
 variant the font server offers first.
 You may set a default enconding via the corresponding X11 resource. E.g.
       gnuplot*encoding: iso8859-15
 The driver also recognizes some common PostScript font names and
 replaces them with possible X11 or TrueType equivalents.
 This same sequence is used to process font requests from `set label`.

 If your gnuplot was built with configuration option --enable-x11-mbfonts,
 you can specify multi-byte fonts by using the prefix "mbfont:" on the font
 name. An additional font may be given, separated by a semicolon.
 Since multi-byte font encodings are interpreted according to the locale
 setting, you must make sure that the environmental variable LC_CTYPE is set
 to some appropriate locale value such as ja_JP.eucJP, ko_KR.EUC, or zh_CN.EUC.

 Example:
       set term x11 font 'mbfont:kana14;k14'
             # 'kana14' and 'k14' are Japanese X11 font aliases, and ';'
             # is the separator of font names.
       set term x11 font 'mbfont:fixed,16,r,medium'
             # <font>,<size>,<slant>,<weight> form is also usable.
       set title '(mb strings)' font 'mbfont:*-fixed-medium-r-normal--14-*'

 The same syntax applies to the default font in Xresources settings,
 for example,
       gnuplot*font: \
           mbfont:-misc-fixed-medium-r-normal--14-*-*-*-c-*-jisx0208.1983-0

 If gnuplot is built with --enable-x11-mbfonts, you can use two special
 PostScript font names 'Ryumin-Light-*' and 'GothicBBB-Medium-*' (standard
 Japanese PS fonts) without the prefix "mbfont:".

?commands set terminal x11 command-line-options
?set terminal x11 command-line-options
?set term x11 command-line-options
?x11 command-line-options
?command-line-options
 In addition to the X Toolkit options, the following options may be specified
 on the command line when starting `gnuplot` or as resources in your
 ".Xdefaults" file (note that `raise` and `persist` can be overridden
 later by `set term x11 [no]raise [no]persist)`:
  `-mono`     forces monochrome rendering on color displays.
  `-gray`     requests grayscale rendering on grayscale or color displays.
              (Grayscale displays receive monochrome rendering by default.)
  `-clear`    requests that the window be cleared momentarily before a
              new plot is displayed.
  `-tvtwm`    requests that geometry specifications for position of the
              window be made relative to the currently displayed portion
              of the virtual root.
  `-raise`    raises plot window after each plot
  `-noraise`  does not raise plot window after each plot
  `-noevents` does not process mouse and key events
  `-ctrlq   ` closes window on ctrl-q rather than q
  `-persist`  plot windows survive after main gnuplot program exits
 The options are shown above in their command-line syntax.  When entered as
 resources in ".Xdefaults", they require a different syntax.

 Example:
       gnuplot*gray:  on
       gnuplot*ctrlq: on

 `gnuplot` also provides a command line option (`-pointsize <v>`) and a
 resource, `gnuplot*pointsize: <v>`, to control the size of points plotted
 with the `points` plotting style.  The value `v` is a real number (greater
 than 0 and less than or equal to ten) used as a scaling factor for point
 sizes.  For example, `-pointsize 2` uses points twice the default size, and
 `-pointsize 0.5` uses points half the normal size.

 The `-noevents` switch disables all mouse and key event processing (except
 for `q` and `<space>` for closing the window). This is useful for programs
 which use the x11 driver independent of the gnuplot main program.

 The `-ctrlq` switch changes the hot-key that closes a plot window from `q`
 to `<ctrl>q`. This is useful is you are using the keystroke-capture feature
 `pause mouse keystroke`, since it allows the character `q` to be captured
 just as all other alphanumeric characters. The `-ctrlq` switch similarly
 replaces the <space> hot-key with <ctrl><space> for the same reason.

?commands set terminal x11 monochrome_options
?set terminal x11 monochrome_options
?set term x11 monochrome_options
?x11 monochrome_options
?monochrome_options
 For monochrome displays, `gnuplot` does not honor foreground or background
 colors.  The default is black-on-white.  `-rv` or `gnuplot*reverseVideo: on`
 requests white-on-black.

?commands set terminal x11 color_resources
?set terminal x11 color_resources
?set term x11 color_resources
?x11 color_resources
?color_resources
 The X11 terminal honors the following resources (shown here with their
 default values) or the greyscale resources.  The values may be color names
 as listed in the X11 rgb.txt file on your system, hexadecimal RGB color
 specifications (see X11 documentation), or a color name followed by a comma
 and an `intensity` value from 0 to 1.  For example, `blue, 0.5` means a half
 intensity blue.
  gnuplot*background:  white
  gnuplot*textColor:   black
  gnuplot*borderColor: black
  gnuplot*axisColor:   black
  gnuplot*line1Color:  red
  gnuplot*line2Color:  green
  gnuplot*line3Color:  blue
  gnuplot*line4Color:  magenta
  gnuplot*line5Color:  cyan
  gnuplot*line6Color:  sienna
  gnuplot*line7Color:  orange
  gnuplot*line8Color:  coral

 The command-line syntax for these is simple only for background,
 which maps directly to the usual X11 toolkit option "-bg".  All
 others can only be set on the command line by use of the generic
 "-xrm" resource override option

 Examples:

       gnuplot -background coral
 to change the background color.

       gnuplot -xrm 'gnuplot*line1Color:blue'
 to override the first linetype color.

?commands set terminal x11 grayscale_resources
?set terminal x11 grayscale_resources
?set term x11 grayscale_resources
?x11 grayscale_resources
?grayscale_resources
 When `-gray` is selected, `gnuplot` honors the following resources for
 grayscale or color displays (shown here with their default values).  Note
 that the default background is black.
  gnuplot*background: black
  gnuplot*textGray:   white
  gnuplot*borderGray: gray50
  gnuplot*axisGray:   gray50
  gnuplot*line1Gray:  gray100
  gnuplot*line2Gray:  gray60
  gnuplot*line3Gray:  gray80
  gnuplot*line4Gray:  gray40
  gnuplot*line5Gray:  gray90
  gnuplot*line6Gray:  gray50
  gnuplot*line7Gray:  gray70
  gnuplot*line8Gray:  gray30

?commands set terminal x11 line_resources
?set terminal x11 line_resources
?set term x11 line_resources
?x11 line_resources
?line_resources
 `gnuplot` honors the following resources for setting the width (in pixels) of
 plot lines (shown here with their default values.)  0 or 1 means a minimal
 width line of 1 pixel width.  A value of 2 or 3 may improve the appearance of
 some plots.
  gnuplot*borderWidth: 2
  gnuplot*axisWidth:   0
  gnuplot*line1Width:  0
  gnuplot*line2Width:  0
  gnuplot*line3Width:  0
  gnuplot*line4Width:  0
  gnuplot*line5Width:  0
  gnuplot*line6Width:  0
  gnuplot*line7Width:  0
  gnuplot*line8Width:  0

 `gnuplot` honors the following resources for setting the dash style used for
 plotting lines.  0 means a solid line.  A two-digit number `jk` (`j` and `k`
 are >= 1 and <= 9) means a dashed line with a repeated pattern of `j` pixels
 on followed by `k` pixels off.  For example, '16' is a dotted line with one
 pixel on followed by six pixels off.  More elaborate on/off patterns can be
 specified with a four-digit value.  For example, '4441' is four on, four off,
 four on, one off.  The default values shown below are for monochrome displays
 or monochrome rendering on color or grayscale displays.
 Color displays default to dashed:off 
  gnuplot*dashed:       off
  gnuplot*borderDashes:   0
  gnuplot*axisDashes:    16
  gnuplot*line1Dashes:    0
  gnuplot*line2Dashes:   42
  gnuplot*line3Dashes:   13
  gnuplot*line4Dashes:   44
  gnuplot*line5Dashes:   15
  gnuplot*line6Dashes: 4441
  gnuplot*line7Dashes:   42
  gnuplot*line8Dashes:   13

?commands set terminal x11 pm3d_resources
?set terminal x11 pm3d_resources
?set term x11 pm3d_resources
?x11 pm3d_resources
?pm3d_resources
?x11 pm3d
 Choosing the appropriate visual class and number of colors is a crucial
 point in X11 applications and a bit awkward, since X11 supports six visual
 types in different depths.

 By default `gnuplot` uses the default visual of the screen. The number of
 colors which can be allocated depends on the visual class chosen. On a
 visual class with a depth > 12bit, gnuplot starts with a maximal number
 of 0x200 colors.  On a visual class with a depth > 8bit (but <= 12 bit)
 the maximal number of colors is 0x100, on <= 8bit displays the maximum
 number of colors is 240 (16 are left for line colors).

 Gnuplot first starts to allocate the maximal number of colors as stated
 above.  If this fails, the number of colors is reduced by the factor 2
 until gnuplot gets all colors which are requested. If dividing `maxcolors`
 by 2 repeatedly results in a number which is smaller than `mincolors`
 `gnuplot` tries to install a private colormap. In this case the window
 manager is responsible for swapping colormaps when the pointer is moved
 in and out the x11 driver's window.

 The default for `mincolors` is maxcolors / (num_colormaps > 1 ? 2 : 8),
 where num_colormaps is the number of colormaps which are currently used
 by gnuplot (usually 1, if only one x11 window is open).

 Some systems support multiple (different) visual classes together on one
 screen. On these systems it might be necessary to force gnuplot to use a
 specific visual class, e.g. the default visual might be 8bit PseudoColor
 but the screen would also support 24bit TrueColor which would be the
 preferred choice.

 The information about an Xserver's capabilities can be obtained with the
 program `xdpyinfo`.  For the visual names below you can choose one of
 StaticGray, GrayScale, StaticColor, PseudoColor, TrueColor, DirectColor.
 If an Xserver supports a requested visual type at different depths,
 `gnuplot` chooses the visual class with the highest depth (deepest).
 If the requested visual class matches the default visual and multiple
 classes of this type are supported, the default visual is preferred.

 Example: on an 8bit PseudoColor visual you can force a private color map
 by specifying `gnuplot*maxcolors: 240` and `gnuplot*mincolors: 240`.

  gnuplot*maxcolors:  <integer>
  gnuplot*mincolors:  <integer>
  gnuplot*visual:     <visual name>

?commands set terminal x11 other_resources
?set terminal x11 other_resources
?set term x11 other_resources
?x11 other_resources
 By default the contents of the current plot window are exported to the X11
 clipboard in response to X events in the window. Setting the resource
 'gnuplot*exportselection' to 'off' or 'false' will disable this.

 By default text rotation is done using a method that is fast, but can
 corrupt nearby colors depending on the background.  If this is a problem,
 you can set the resource 'gnuplot.fastrotate' to 'off'

  gnuplot*exportselection:  off
  gnuplot*fastrotate:  on
  gnuplot*ctrlq:  off
?commands set terminal xlib
?set terminal xlib
?set term xlib
?terminal xlib
?term xlib
?xlib
 The `xlib` terminal driver supports the X11 Windows System.  It generates
 gnuplot_x11 commands, but sends them to the output file specified by
 `set output '<filename>'`. `set term x11` is equivalent to
 `set output "|gnuplot_x11 -noevents"; set term xlib`.
 `xlib` takes the same set of options as `x11`.
?commands set terminal canvas
?set terminal canvas
?set term canvas
?terminal canvas
?term canvas

 The `canvas` terminal creates a set of javascript commands that draw onto the
 HTML5 canvas element.
 Syntax:
       set terminal canvas {size <xsize>, <ysize>} {background <rgb_color>}
                           {font {<fontname>}{,<fontsize>}} | {fsize <fontsize>}
                           {{no}enhanced} {linewidth <lw>}
                           {rounded | butt}
                           {solid | dashed {dashlength <dl>}}
                           {standalone {mousing} | name '<funcname>'}
                           {jsdir 'URL/for/javascripts'}
                           {title '<some string>'}

 where <xsize> and <ysize> set the size of the plot area in pixels.
 The default size in standalone mode is 600 by 400 pixels.
 The default font size is 10.

 NB: Only one font is available, the ascii portion of Hershey simplex Roman
 provided in the file canvastext.js. You can replace this with the file
 canvasmath.js, which contains also UTF-8 encoded Hershey simplex Greek and
 math symbols. For consistency with other terminals, it is also possible to
 use `font "name,size"`. Currently the font `name` is ignored, but browser
 support for named fonts is likely to arrive eventually.

 The default `standalone` mode creates an html page containing javascript
 code that renders the plot using the HTML 5 canvas element.  The html page
 links to two required javascript files 'canvastext.js' and 'gnuplot_common.js'.
 An additional file 'gnuplot_dashedlines.js' is needed to support dashed lines.
 By default these point to local files, on unix-like systems usually in
 directory /usr/local/share/gnuplot/<version>/js.  See installation notes for
 other platforms. You can change this by using the `jsdir` option to specify
 either a different local directory or a general URL.  The latter is usually
 appropriate if the plot is exported for viewing on remote client machines.

 All plots produced by the canvas terminal are mouseable.  The additional
 keyword `mousing` causes the `standalone` mode to add a mouse-tracking box
 underneath the plot. It also adds a link to a javascript file
 'gnuplot_mouse.js' and to a stylesheet for the mouse box 'gnuplot_mouse.css'
 in the same local or URL directory as 'canvastext.js'.

 The `name` option creates a file containing only javascript. Both the
 javascript function it contains and the id of the canvas element that it
 draws onto are taken from the following string parameter.  The commands
       set term canvas name 'fishplot'
       set output 'fishplot.js'
 will create a file containing a javascript function fishplot() that will
 draw onto a canvas with id=fishplot.  An html page that invokes this
 javascript function must also load the canvastext.js function as described
 above.  A minimal html file to wrap the fishplot created above might be:

       <html>
       <head>
           <script src="canvastext.js"></script>
           <script src="gnuplot_common.js"></script>
       </head>
       <body onload="fishplot();">
           <script src="fishplot.js"></script>
           <canvas id="fishplot" width=600 height=400>
               <div id="err_msg">No support for HTML 5 canvas element</div>
           </canvas>
       </body>
       </html>

 The individual plots drawn on this canvas will have names fishplot_plot_1,
 fishplot_plot_2, and so on. These can be referenced by external javascript
 routines, for example gnuplot.toggle_visibility("fishplot_plot_2").

?commands set terminal cgm
?set terminal cgm
?set term cgm
?terminal cgm
?term cgm
?cgm
 The `cgm` terminal generates a Computer Graphics Metafile, Version 1. 
 This file format is a subset of the ANSI X3.122-1986 standard entitled
 "Computer Graphics - Metafile for the Storage and Transfer of Picture
 Description Information".

 Syntax:
       set terminal cgm {color | monochrome} {solid | dashed} {{no}rotate}
                        {<mode>} {width <plot_width>} {linewidth <line_width>}
                        {font "<fontname>,<fontsize>"}
                        {background <rgb_color>}
   [deprecated]         {<color0> <color1> <color2> ...}

 `solid` draws all curves with solid lines, overriding any dashed patterns;
 <mode> is `landscape`, `portrait`, or `default`;
 <plot_width> is the assumed width of the plot in points; 
 <line_width> is the line width in points (default 1); 
 <fontname> is the name of a font (see list of fonts below)
 <fontsize> is the size of the font in points (default 12).

 The first six options can be in any order.  Selecting `default` sets all
 options to their default values.

 The mechanism of setting line colors in the `set term` command is
 deprecated.  Instead you should set the background using a separate
 keyword and set the line colors using `set linetype`.
 The deprecated mechanism accepted colors of the form 'xrrggbb', where x is
 the literal character 'x' and 'rrggbb' are the red, green and blue components
 in hex. The first color was used for the background, subsequent colors are
 assigned to successive line types.

 Examples:
       set terminal cgm landscape color rotate dashed width 432 \
                      linewidth 1  'Helvetica Bold' 12       # defaults
       set terminal cgm linewidth 2  14  # wider lines & larger font
       set terminal cgm portrait "Times Italic" 12
       set terminal cgm color solid      # no pesky dashes!
?commands set terminal cgm font
?set terminal cgm font
?set term cgm font
?cgm font
 The first part of a Computer Graphics Metafile, the metafile description,
 includes a font table.  In the picture body, a font is designated by an
 index into this table.  By default, this terminal generates a table with
 the following 35 fonts, plus six more with `italic` replaced by
 `oblique`, or vice-versa (since at least the Microsoft Office and Corel
 Draw CGM import filters treat `italic` and `oblique` as equivalent):
       Helvetica
       Helvetica Bold
       Helvetica Oblique
       Helvetica Bold Oblique
       Times Roman
       Times Bold
       Times Italic
       Times Bold Italic
       Courier
       Courier Bold
       Courier Oblique
       Courier Bold Oblique
       Symbol
       Hershey/Cartographic_Roman
       Hershey/Cartographic_Greek
       Hershey/Simplex_Roman
       Hershey/Simplex_Greek
       Hershey/Simplex_Script
       Hershey/Complex_Roman
       Hershey/Complex_Greek
       Hershey/Complex_Script
       Hershey/Complex_Italic
       Hershey/Complex_Cyrillic
       Hershey/Duplex_Roman
       Hershey/Triplex_Roman
       Hershey/Triplex_Italic
       Hershey/Gothic_German
       Hershey/Gothic_English
       Hershey/Gothic_Italian
       Hershey/Symbol_Set_1
       Hershey/Symbol_Set_2
       Hershey/Symbol_Math
       ZapfDingbats
       Script
       15
 The first thirteen of these fonts are required for WebCGM.  The
 Microsoft Office CGM import filter implements the 13 standard fonts
 listed above, and also 'ZapfDingbats' and 'Script'.  However, the
 script font may only be accessed under the name '15'.  For more on
 Microsoft import filter font substitutions, check its help file which
 you may find here:
   C:\Program Files\Microsoft Office\Office\Cgmimp32.hlp
 and/or its configuration file, which you may find here:
   C:\Program Files\Common Files\Microsoft Shared\Grphflt\Cgmimp32.cfg

 In the `set term` command, you may specify a font name which does not
 appear in the default font table.  In that case, a new font table is
 constructed with the specified font as its first entry. You must ensure
 that the spelling, capitalization, and spacing of the name are
 appropriate for the application that will read the CGM file.  (Gnuplot
 and any MIL-D-28003A compliant application ignore case in font names.)
 If you need to add several new fonts, use several `set term` commands.

 Example:
       set terminal cgm 'Old English'
       set terminal cgm 'Tengwar'
       set terminal cgm 'Arabic'
       set output 'myfile.cgm'
       plot ...
       set output

 You cannot introduce a new font in a `set label` command.
?commands set terminal cgm fontsize
?set terminal cgm fontsize
?set term cgm fontsize
?cgm fontsize
 Fonts are scaled assuming the page is 6 inches wide.  If the `size`
 command is used to change the aspect ratio of the page or the CGM file
 is converted to a different width, the resulting font sizes will be
 scaled up or down accordingly.  To change the assumed width, use the
 `width` option.
?commands set terminal cgm linewidth
?set terminal cgm linewidth
?set term cgm linewidth
?cgm linewidth
 The `linewidth` option sets the width of lines in pt.  The default width
 is 1 pt.  Scaling is affected by the actual width of the page, as
 discussed under the `fontsize` and `width` options.
?commands set terminal cgm rotate
?set terminal cgm rotate
?set term cgm rotate
?cgm rotate
 The `norotate` option may be used to disable text rotation.  For
 example, the CGM input filter for Word for Windows 6.0c can accept
 rotated text, but the DRAW editor within Word cannot.  If you edit a
 graph (for example, to label a curve), all rotated text is restored to
 horizontal.  The Y axis label will then extend beyond the clip boundary.
 With `norotate`, the Y axis label starts in a less attractive location,
 but the page can be edited without damage.  The `rotate` option confirms
 the default behavior.
?set terminal cgm solid
?set term cgm solid
?cgm solid
 The `solid` option may be used to disable dashed line styles in the
 plots.  This is useful when color is enabled and the dashing of the
 lines detracts from the appearance of the plot. The `dashed` option
 confirms the default behavior, which gives a different dash pattern to
 each line type.
?commands set terminal cgm size
?set terminal cgm size
?set term cgm size
?cgm size
 Default size of a CGM plot is 32599 units wide and 23457 units high for
 landscape, or 23457 units wide by 32599 units high for portrait.
?commands set terminal cgm width
?set terminal cgm width
?set term cgm width
?cgm width
 All distances in the CGM file are in abstract units.  The application
 that reads the file determines the size of the final plot.  By default,
 the width of the final plot is assumed to be 6 inches (15.24 cm).  This
 distance is used to calculate the correct font size, and may be changed
 with the `width` option.  The keyword should be followed by the width in
 points.  (Here, a point is 1/72 inch, as in PostScript.  This unit is
 known as a "big point" in TeX.)  Gnuplot `expressions` can be used to
 convert from other units.

 Example:
       set terminal cgm width 432            # default
       set terminal cgm width 6*72           # same as above
       set terminal cgm width 10/2.54*72     # 10 cm wide
?commands set terminal cgm nofontlist
?set terminal cgm nofontlist
?set term cgm nofontlist
?cgm nofontlist
?set terminal cgm winword6
?set term cgm winword6
?cgm winword6
 The default font table includes the fonts recommended for WebCGM, which
 are compatible with the Computer Graphics Metafile input filter for
 Microsoft Office and Corel Draw.  Another application might use
 different fonts and/or different font names, which may not be
 documented.  The `nofontlist` (synonym `winword6`) option deletes the font
 table from the CGM file.  In this case, the reading application should
 use a default table.  Gnuplot will still use its own default font table
 to select font indices.  Thus, 'Helvetica' will give you an index of 1,
 which should get you the first entry in your application's default font
 table. 'Helvetica Bold' will give you its second entry, etc.

?commands set terminal corel
?set terminal corel
?set term corel
?terminal corel
?term corel
?corel
 The `corel` terminal driver supports CorelDraw.

 Syntax:
       set terminal corel {  default
                           | {monochrome | color
                                {"<font>" {<fontsize> 
                                   {<xsize> <ysize> {<linewidth> }}}}}

 where the fontsize and linewidth are specified in points and the sizes in
 inches.  The defaults are monochrome, "SwitzerlandLight", 22, 8.2, 10 and 1.2.
?commands set terminal dumb
?set terminal dumb
?set term dumb
?terminal dumb
?term dumb
?dumb
 The `dumb` terminal driver plots into a text block using ascii characters.
 It has an optional size specification and a trailing linefeed flag.

 Syntax:
       set terminal dumb {size <xchars>,<ychars>} {[no]feed}
                         {[no]enhanced}

 where <xchars> and <ychars> set the size of the text block. The default is
 79 by 24. The last newline is printed only if `feed` is enabled.

 Example:
       set term dumb size 60,15
       plot [-5:6.5] sin(x) with impulse

            1 +-------------------------------------------------+
          0.8 +|||++                   ++||||++   sin(x) +----+ |
          0.6 +|||||+                 ++|||||||+                |
          0.4 +||||||+               ++|||||||||+               |
          0.2 +|||||||+             ++|||||||||||+             +|
            0 ++++++++++++++++++++++++++++++++++++++++++++++++++|
         -0.2 +        +|||||||||||+              +|||||||||||+ |
         -0.4 +         +|||||||||+                +|||||||||+  |
         -0.6 +          +|||||||+                  +|||||||+   |
         -0.8 +   +       ++||||+   +       +        ++||||+  + |
           -1 +---+--------+--------+-------+--------+--------+-+
                 -4       -2        0       2        4        6  
?commands set terminal dxf
?set terminal dxf
?set term dxf
?terminal dxf
?term dxf
?dxf
 The `dxf` terminal driver creates pictures that can be imported into AutoCad
 (Release 10.x).  It has no options of its own, but some features of its plots
 may be modified by other means.  The default size is 120x80 AutoCad units,
 which can be changed by `set size`.  `dxf` uses seven colors (white, red,
 yellow, green, cyan, blue and magenta), which can be changed only by
 modifying the source file.  If a black-and-white plotting device is used, the
 colors are mapped to differing line thicknesses.  See the description of the
 AutoCad print/plot command.
?commands set terminal emf
?set terminal emf
?set term emf
?terminal emf
?term emf
?emf
 The `emf` terminal generates an Enhanced Metafile Format file.
 This file format is recognized by many Windows applications.

 Syntax:
       set terminal emf {color | monochrome} {solid | dashed}
                        {enhanced {noproportional}}
                        {rounded | butt}
                        {linewidth <LW>} {dashlength <DL>}
                        {size XX,YY} {background <rgb_color>}
                        {font "<fontname>{,<fontsize>}"}
                        {fontscale <scale>}

 In `monochrome` mode successive line types cycle through dash patterns.
 In `color` mode successive line types use successive colors, and only after
 all 8 default colors are exhausted is the dash pattern incremented.
 `solid` draws all curves with solid lines, overriding any dashed patterns;
 `linewidth <factor>` multiplies all line widths by this factor.
 `dashlength <factor>` is useful for thick lines.
 <fontname> is the name of a font; and 
 `<fontsize>` is the size of the font in points.

 The nominal size of the output image defaults to 1024x768 in arbitrary
 units. You may specify a different nominal size using the `size` option.

 Enhanced text mode tries to approximate proportional character spacing.
 If you are using a monospaced font, or don't like the approximation, you
 can turn off this correction using the `noproportional` option.

 The default settings are `color solid font "Arial,12" size 1024,768`
 Selecting `default` sets all options to their default values.

 Examples:
       set terminal emf 'Times Roman Italic, 12'
       set terminal emf dashed    # otherwise all lines are solid
?commands set terminal fig
?set terminal fig
?set term fig
?terminal fig
?term fig
?fig
?xfig
 The `fig` terminal device generates output in the Fig graphics language.

 Syntax:
       set terminal fig {monochrome | color}
                        {landscape | portrait}
                        {small | big | size <xsize> <ysize>}
                        {metric | inches}
                        {pointsmax <max_points>}
                        {solid | dashed}
                        {font "<fontname>{,<fontsize>}"}
                        {textnormal | {textspecial texthidden textrigid}}
                        {{thickness|linewidth} <units>}
                        {depth <layer>}
                        {version <number>}

 `monochrome` and `color` determine whether the picture is black-and-white or
 `color`.  `small` and `big` produce a 5x3 or 8x5 inch graph in the default
 `landscape` mode and 3x5 or 5x8 inches in `portrait` mode.
 `size` sets (overrides) the size of the drawing
 area to <xsize>*<ysize> in units of inches or centimeters depending on the
 `inches` or `metric` setting in effect.
 The latter settings is also used as default units for editing with "xfig".

 `pointsmax <max_points>` sets the maximum number of points per polyline.

 `solid` inhibits automatic usage of `dash`ed lines when solid linestyles are
 used up, which otherwise occurs.

 `font` sets the text font face to <fontname> and its size to <fontsize>
 points. `textnormal` resets the text flags and selects postscript fonts,
 `textspecial` sets the text flags for LaTeX specials, `texthidden` sets the
 hidden flag and `textrigid` the rigid flag.

 `depth` sets the default depth layer for all lines and text.  The default
 depth is 10 to leave room for adding material with "xfig" on top of the
 plot.

 `version` sets the format version of the generated fig output. Currently
 only versions 3.1 and 3.2 are supported.

 `thickness` sets the default line thickness, which is 1 if not specified.
 Overriding the thickness can be achieved by adding a multiple of 100 to the
 `linetype` value for a `plot` command.  In a similar way the `depth`
 of plot elements (with respect to the default depth) can be controlled by
 adding a multiple of 1000 to <linetype>.  The depth is then <layer> +
 <linetype>/1000 and the thickness is (<linetype>%1000)/100 or, if that is
 zero, the default line thickness. `linewidth` is a synonym for `thickness`.

 Additional point-plot symbols are also available with the `fig` driver. The
 symbols can be used through `pointtype` values % 100 above 50, with different
 fill intensities controlled by <pointtype> % 5 and outlines in black (for
 <pointtype> % 10 < 5) or in the current color.  Available symbols are
         50 - 59:  circles
         60 - 69:  squares
         70 - 79:  diamonds
         80 - 89:  upwards triangles
         90 - 99:  downwards triangles
 The size of these symbols is linked to the font size.  The depth of symbols
 is by default one less than the depth for lines to achieve nice error bars.
 If <pointtype> is above 1000, the depth is <layer> + <pointtype>/1000-1.  If
 <pointtype>%1000 is above 100, the fill color is (<pointtype>%1000)/100-1.

 Available fill colors are (from 1 to 9): black, blue, green, cyan, red,
 magenta, yellow, white and dark blue (in monochrome mode: black for 1 to 6
 and white for 7 to 9).

 See `plot with` for details of <linetype> and <pointtype>.

 The `big` option is a substitute for the `bfig` terminal in earlier versions,
 which is no longer supported.

 Examples:
       set terminal fig monochrome small pointsmax 1000  # defaults

       plot 'file.dat' with points linetype 102 pointtype 759
 would produce circles with a blue outline of width 1 and yellow fill color.

       plot 'file.dat' using 1:2:3 with err linetype 1 pointtype 554
 would produce errorbars with black lines and circles filled red.  These
 circles are one layer above the lines (at depth 9 by default).

 To plot the error bars on top of the circles use
       plot 'file.dat' using 1:2:3 with err linetype 1 pointtype 2554
?commands set terminal hp2623a
?set terminal hp2623a
?set term hp2623a
?terminal hp2623a
?term hp2623a
?hp2623a
 The `hp2623a` terminal driver supports the Hewlett Packard HP2623A.  It has
 no options.
?commands set terminal hp2648
?set terminal hp2648
?set term hp2648
?terminal hp2648
?term hp2648
?hp2648
 The `hp2648` terminal driver supports the Hewlett Packard HP2647 and HP2648.
 It has no options.
?commands set terminal hpgl
?set terminal hpgl
?set term hpgl
?terminal hpgl
?term hpgl
?hpgl
?commands set terminal pcl5
?set terminal pcl5
?set term pcl5
?terminal pcl5
?term pcl5
?pcl5
 The `hpgl` driver produces HPGL output for devices like the HP7475A plotter.
 There are two options which can be set: the number of pens and `eject`,
 which tells the plotter to eject a page when done.  The default is to use 6
 pens and not to eject the page when done.

 The international character sets ISO-8859-1 and CP850 are recognized via
 `set encoding iso_8859_1` or `set encoding cp850` (see `set encoding` for
 details).

 Syntax:
       set terminal hpgl {<number_of_pens>} {eject}

 The selection

       set terminal hpgl 8 eject

 is equivalent to the previous `hp7550` terminal, and the selection

       set terminal hpgl 4

 is equivalent to the previous `hp7580b` terminal.

 The `pcl5` driver supports plotters such as the Hewlett-Packard Designjet
 750C, the Hewlett-Packard Laserjet III, and the Hewlett-Packard Laserjet IV.
 It actually uses HPGL-2, but there is a name conflict among the terminal
 devices.  It has several options which must be specified in the order
 indicated below:

 Syntax:
       set terminal pcl5 {mode <mode>} {<plotsize>}
           {{color {<number_of_pens>}} | monochrome} {solid | dashed}
           {font <font>} {size <fontsize>} {pspoints | nopspoints}

 <mode> is `landscape` or `portrait`. <plotsize> is the physical
 plotting size of the plot, which is one of the following: `letter` for
 standard (8 1/2" X 11") displays, `legal` for (8 1/2" X 14") displays,
 `noextended` for (36" X 48") displays (a letter size ratio) or,
 `extended` for (36" X 55") displays (almost a legal size ratio).
 `color` is for multi-pen (i.e. color) plots, and <number_of_pens> is
 the number of pens (i.e. colors) used in color plots. `monochrome` is for
 one (e.g. black) pen plots. `solid` draws all lines as solid lines, or
 `dashed` will draw lines with different dashed and dotted line patterns.
 <font> is `stick`, `univers`, `cg_times`, `zapf_dingbats`, `antique_olive`,
 `arial`, `courier`, `garamond_antigua`, `letter_gothic`, `cg_omega`,
 `albertus`, `times_new_roman`, `clarendon`, `coronet`, `marigold`,
 `truetype_symbols`, or `wingdings`. <fontsize> is the font size in points.
 The point type selection can be the standard default set by specifying
 `nopspoints`, or the same set of point types found in the postscript terminal
 by specifying `pspoints`.

 Note that built-in support of some of these options is printer device
 dependent. For instance, all the fonts are supposedly supported by the HP
 Laserjet IV, but only a few (e.g. univers, stick) may be supported by the HP
 Laserjet III and the Designjet 750C. Also, color obviously won't work on the
 the laserjets since they are monochrome devices.

 Defaults: landscape, noextended, color (6 pens), solid, univers, 12 point,
           and nopspoints.

 With `pcl5` international characters are handled by the printer; you just put
 the appropriate 8-bit character codes into the text strings.  You don't need
 to bother with `set encoding`.

 HPGL graphics can be imported by many software packages.
?commands set terminal imagen
?set terminal imagen
?set term imagen
?terminal imagen
?term imagen
?imagen
 The `imagen` terminal driver supports Imagen laser printers.  It is capable
 of placing multiple graphs on a single page.

 Syntax:
       set terminal imagen {<fontsize>} {portrait | landscape}
                           {[<horiz>,<vert>]}

 where `fontsize` defaults to 12 points and the layout defaults to `landscape`.
 `<horiz>` and `<vert>` are the number of graphs in the horizontal and
 vertical directions; these default to unity.

 Example:
       set terminal imagen portrait [2,3]

 puts six graphs on the page in three rows of two in portrait orientation.
?commands set terminal mif
?set terminal mif
?set term mif
?terminal mif
?term mif
?mif
 The `mif` terminal driver produces Frame Maker MIF format version 3.00.  It
 plots in MIF Frames with the size 15*10 cm, and plot primitives with the same
 pen will be grouped in the same MIF group.  Plot primitives in a `gnuplot`
 page will be plotted in a MIF Frame, and several MIF Frames are collected in
 one large MIF Frame.  The MIF font used for text is "Times".

 Several options may be set in the MIF 3.00 driver.

 Syntax:
       set terminal mif {color | colour | monochrome} {polyline | vectors}
                        {help | ?}

 `colour` plots lines with line types >= 0 in colour (MIF sep. 2--7) and
 `monochrome` plots all line types in black (MIF sep. 0).
 `polyline` plots curves as continuous curves and `vectors` plots curves as
 collections of vectors.
 `help` and `?` print online help on standard error output---both print a
 short description of the usage; `help` also lists the options.

 Examples:
       set term mif colour polylines    # defaults
       set term mif                     # defaults
       set term mif vectors
       set term mif help
?commands set terminal png
?set terminal png
?set term png
?terminal png
?term png
?png
 Syntax:
       set terminal png 
              {{no}enhanced}
              {{no}transparent} {{no}interlace}
              {{no}truecolor} {rounded|butt}
              {linewidth <lw>} {dashlength <dl>}
              {tiny | small | medium | large | giant}
              {font "<face> {,<pointsize>}"} {fontscale <scale>}
              {size <x>,<y>} {{no}crop}
              {background <rgb_color>}

 PNG, JPEG and GIF images are created using the external library libgd.
 PNG plots may be viewed interactively by piping the output to the
 'display' program from the ImageMagick package as follows:
                set term png
                set output '| display png:-'
 You can view the output from successive plot commands interactively by typing
 <space> in the display window.  To save the current plot to a file,
 left click in the display window and choose `save`.

 `transparent` instructs the driver to make the background color transparent.
 Default is `notransparent`.

 `interlace` instructs the driver to generate interlaced PNGs.
 Default is `nointerlace`.

 The `linewidth` and `dashlength` options are scaling factors that affect all
 lines drawn, i.e. they are multiplied by values requested in various drawing
 commands.

 By default output png images use 256 indexed colors. The `truecolor` option
 instead creates TrueColor images with 24 bits of color information per pixel.
 Transparent fill styles require the `truecolor` option. See `fillstyle`.
 A transparent background is possible in either indexed or TrueColor images.

 `butt` instructs the driver to use a line drawing method that does
 not overshoot the desired end point of a line.  This setting is only
 applicable for line widths greater than 1.  This setting is most useful when
 drawing horizontal or vertical lines.  Default is `rounded`.

 The details of font selection are complicated.
 Two equivalent simple examples are given below:
      set term png font arial 11
      set term png font "arial,11"
 For more information please see the separate section under `fonts`.

 The output plot size <x,y> is given in pixels---it defaults to 640x480.
 Please see additional information under `canvas` and `set size`.
 Blank space at the edges of the finished plot may be trimmed using the `crop`
 option, resulting in a smaller final image size. Default is `nocrop`.

?set term png examples
       set terminal png medium size 640,480 background '#ffffff'

 Use the medium size built-in non-scaleable, non-rotatable font.
 Use white (24-bit RGB in hexadecimal) for the non-transparent background.

       set terminal png font arial 14 size 800,600

 Searches for a scalable font with face name 'arial' and sets the font
 size to 14pt.  Please see `fonts` for details of how the font search
 is done.

       set terminal png transparent truecolor enhanced

 Use 24 bits of color information per pixel, with a transparent background.
 Use the `enhanced text` mode to control the layout of strings to be printed.

?commands set terminal jpeg
?set terminal jpeg
?set term jpeg
?terminal jpeg
?term jpeg
?jpeg
 Syntax:
       set terminal jpeg 
              {{no}enhanced}
              {{no}interlace}
              {linewidth <lw>} {dashlength <dl>} {rounded|butt}
              {tiny | small | medium | large | giant}
              {font "<face> {,<pointsize>}"} {fontscale <scale>}
              {size <x>,<y>} {{no}crop}
              {background <rgb_color>}

 PNG, JPEG and GIF images are created using the external library libgd.
 In most cases, PNG is to be preferred for single plots, and GIF for
 animations.  Both are loss-less image formats, and produce better image
 quality than the lossy JPEG format. This is in particular noticeable
 for solid color lines against a solid background, i.e. exactly the sort
 of image typically created by gnuplot.

 The `interlace` option creates a progressive JPEG image.
 Default is `nointerlace`.

 The `linewidth` and `dashlength` options are scaling factors that affect all
 lines drawn, i.e. they are multiplied by values requested in various drawing
 commands.

 `butt` instructs the driver to use a line drawing method that does
 not overshoot the desired end point of a line.  This setting is only
 applicable for line widths greater than 1.  This setting is most useful when
 drawing horizontal or vertical lines.  Default is `rounded`.

 The details of font selection are complicated.
 Two equivalent simple examples are given below:
      set term jpeg font arial 11
      set term jpeg font "arial,11"
 For more information please see the separate section under `fonts`.

 The output plot size <x,y> is given in pixels---it defaults to 640x480.
 Please see additional information under `canvas` and `set size`.
 Blank space at the edges of the finished plot may be trimmed using the `crop`
 option, resulting in a smaller final image size. Default is `nocrop`.

?commands set terminal gif
?set terminal gif
?set term gif
?terminal gif
?term gif
?gif
 Syntax:
       set terminal gif 
              {{no}enhanced}
              {{no}transparent} {rounded|butt}
              {linewidth <lw>} {dashlength <dl>}
              {tiny | small | medium | large | giant}
              {font "<face> {,<pointsize>}"} {fontscale <scale>}
              {size <x>,<y>} {{no}crop}
              {animate {delay <d>} {loop <n>} {{no}optimize}}
              {background <rgb_color>}

 PNG, JPEG and GIF images are created using the external library libgd.
 GIF plots may be viewed interactively by piping the output to the
 'display' program from the ImageMagick package as follows:
                set term gif
                set output '| display gif:-'
 You can view the output from successive plot commands interactively by typing
 <space> in the display window.  To save the current plot to a file,
 left click in the display window and choose `save`.

 `transparent` instructs the driver to make the background color transparent.
 Default is `notransparent`.

 The `linewidth` and `dashlength` options are scaling factors that affect all
 lines drawn, i.e. they are multiplied by values requested in various drawing
 commands.

 `butt` instructs the driver to use a line drawing method that does
 not overshoot the desired end point of a line.  This setting is only
 applicable for line widths greater than 1.  This setting is most useful when
 drawing horizontal or vertical lines.  Default is `rounded`.

 The details of font selection are complicated.
 Two equivalent simple examples are given below:
      set term gif font arial 11
      set term gif font "arial,11"
 For more information please see the separate section under `fonts`.

 The `animate` option is available only if your local gd library supports
 the creation of animated gifs. The default delay between display of
 successive images may be specified in units of 1/100 second (default 5).
 The actual delay may vary depending on the program used as a viewer.
 Number of animation loops can be specified, default 0 means infinity.
 An animation sequence is terminated by the next `set output` or `set term`
 command.  The `optimize` option has two effects on the animation.

 1) A single color map is used for the entire animation. This requires
 that all colors used in any frame of the animation are already
 defined in the first frame.

 2) If possible, only the portions of a frame that differ from the
 previous frame are stored in the animation file.  This space saving
 may not be possible if the animation uses transparency.

 Both of these optimizations are intended to produce a smaller output file,
 but the decrease in size is probably only significant for long animations
 or very small frame sizes.
 The `nooptimize` option turns off both of the effects just described.
 Each frame is stored in its entirety along with a private color map.
 Note that it is possible to post-process a non-optimized animation
 using external utilities, and this post-processing can yield a smaller
 file than gnuplot's internal optimization mode.
 The default is `nooptimize`.

 The output plot size <x,y> is given in pixels---it defaults to 640x480.
 Please see additional information under `canvas` and `set size`.
 Blank space at the edges of the finished plot may be trimmed using the `crop`
 option, resulting in a smaller final image size. Default is `nocrop`.

?set term gif examples
       set terminal gif medium size 640,480 background '#ffffff'

 Use the medium size built-in non-scaleable, non-rotatable font.
 Use white (24 bit RGB in hexadecimal) for the non-transparent background.

       set terminal gif font arial 14 enhanced

 Searches for a scalable font with face name 'arial' and sets the font
 size to 14pt.  Please see `fonts` for details of how the font search
 is done.  Because this is a scalable font, we can use enhanced text mode.

       set term gif animate transparent opt delay 10 size 200,200
       load "animate2.dem"

 Open the gif terminal for creation of an animated gif file.  The individual
 frames of the animation sequence are created by the script file animate2.dem
 from the standard collection of demos.


?commands set terminal epslatex
?set terminal epslatex
?set term epslatex
?terminal epslatex
?term epslatex
?epslatex
 The `epslatex` driver generates output for further processing by LaTeX.

 Syntax:
       set terminal epslatex   {default}
       set terminal epslatex   {standalone | input}
                               {oldstyle | newstyle}
                               {level1 | leveldefault}
                               {color | colour | monochrome}
                               {background <rgbcolor> | nobackground}
                               {solid | dashed}
                               {dashlength | dl <DL>}
                               {linewidth | lw <LW>}
                               {rounded | butt}
                               {clip | noclip}
                               {palfuncparam <samples>{,<maxdeviation>}}
                               {size <XX>{unit},<YY>{unit}}
                               {header <header> | noheader}
                               {blacktext | colortext | colourtext}
                               {{font} "fontname{,fontsize}" {<fontsize>}}
                               {fontscale <scale>}

 The epslatex terminal prints a plot as `terminal postscript eps`
 but transfers the texts to LaTeX instead of including in the PostScript
 code. Thus, many options are the same as in the `postscript terminal`.

 The appearance of the epslatex terminal changed between versions 4.0 and 4.2
 to reach better consistency with the postscript terminal:
 The plot size has been changed from 5 x 3 inches to 5 x 3.5 inches;
 the character width is now estimated to be 60% of the font size
 while the old epslatex terminal used 50%;  now, the larger number of
 postscript linetypes and symbols are used.  To reach an appearance that is
 nearly identical to the old one specify the option `oldstyle`. (In fact
 some small differences remain: the symbol sizes are slightly different, the
 tics are half as large as in the old terminal which can be changed using
 `set tics scale`, and the arrows have all features as in the postscript
 terminal.)

 If you see the error message
       "Can't find PostScript prologue file ... "
 Please see and follow the instructions in `postscript prologue`.

 The option `color` enables color, while `monochrome` prefers black and white
 drawing elements. Further, `monochrome` uses gray `palette` but it does not
 change color of objects specified with an explicit `colorspec`.
 `solid` draws all plots with solid lines, overriding any dashed patterns.
 `dashlength` or `dl` scales the length of the dashed-line segments by <DL>,
 which is a floating-point number greater than zero.
 `linewidth` or `lw` scales all linewidths by <LW>.

 By default the generated PostScript code uses language features that were
 introduced in PostScript Level 2, notably filters and pattern-fill of
 irregular objects such as filledcurves.  PostScript Level 2 features are
 conditionally protected so that PostScript Level 1 interpreters do not issue
 errors but, rather, display a message or a PostScript Level 1 approximation.
 The `level1` option substitutes PostScript Level 1 approximations of these
 features and uses no PostScript Level 2 code.  This may be required by some
 old printers and old versions of Adobe Illustrator.  The flag `level1` can be
 toggled later by editing a single line in the PostScript output file to force
 PostScript Level 1 interpretation.  In the case of files containing level 2
 code, the above features will not appear or will be replaced by a note when
 this flag is set or when the interpreting program does not indicate that it
 understands level 2 PostScript or higher.

 `rounded` sets line caps and line joins to be rounded; `butt` is the
 default, butt caps and mitered joins.

 `clip` tells PostScript to clip all output to the bounding box;
 `noclip` is the default.

 `palfuncparam` controls how `set palette functions` are encoded as gradients
 in the output. Analytic color component functions (set via
 `set palette functions`) are encoded as linear interpolated gradients in the
 postscript output:  The color component functions are sampled at <samples>
 points and all points are removed from this gradient which can be removed
 without changing the resulting colors by more than <maxdeviation>. For
 almost every useful palette you may safely leave the defaults of
 <samples>=2000 and <maxdeviation>=0.003 untouched.

 The default size for postscript output is 10 inches x 7 inches. The default
 for eps output is 5 x 3.5 inches.  The `size` option changes this to
 whatever the user requests. By default the X and Y sizes are taken to be in
 inches, but other units are possibly (currently only cm). The BoundingBox
 of the plot is correctly adjusted to contain the resized image.
 Screen coordinates always run from 0.0 to 1.0 along the full length of the
 plot edges as specified by the `size` option.
 NB: `this is a change from the previously recommended method of using the
 set size command prior to setting the terminal type`.  The old method left
 the BoundingBox unchanged and screen coordinates did not correspond to the
 actual limits of the plot.

 `blacktext` forces all text to be written in black even in color mode;

 The epslatex driver offers a special way of controlling text positioning:
 (a) If any text string begins with '{', you also need to include a '}' at the
 end of the text, and the whole text will be centered both horizontally
 and vertically by LaTeX.  (b) If the text string begins with '[', you need
 to continue it with: a position specification (up to two out of t,b,l,r,c),
 ']{', the text itself, and finally, '}'. The text itself may be anything
 LaTeX can typeset as an LR-box. \rule{}{}'s may help for best positioning.
 See also the documentation for the `pslatex` terminal driver.
 To create multiline labels, use \shortstack, for example
    set ylabel '[r]{\shortstack{first line \\ second line}}' 

 The `back` option of `set label` commands is handled slightly different
 than in other terminals. Labels using 'back' are printed behind all other
 elements of the plot while labels using 'front' are printed above 
 everything else.

 The driver produces two different files, one for the eps part of the figure
 and one for the LaTeX part. The name of the LaTeX file is taken from the
 `set output` command. The name of the eps file is derived by replacing
 the file extension (normally `.tex`) with `.eps` instead.  There is no
 LaTeX output if no output file is given!  Remember to close the
 `output file` before next plot unless in `multiplot` mode.

 In your LaTeX documents use '\input{filename}' to include the figure.
 The `.eps` file is included by the command \includegraphics{...}, so you
 must also include \usepackage{graphicx} in the LaTeX preamble.  If you
 want to use coloured text (option `textcolour`) you also have to include
 \usepackage{color} in the LaTeX preamble.

 Pdf files can be made from the eps file using 'epstopdf'. If the graphics
 package is properly configured, the LaTeX files can also be processed by
 pdflatex without changes, using the pdf files instead of the eps files.
 The behaviour concerning font selection depends on the header mode.
 In all cases, the given font size is used for the calculation of proper
 spacing. When not using the `standalone` mode the actual LaTeX font and
 font size at the point of inclusion is taken, so use LaTeX commands for
 changing fonts. If you use e.g. 12pt as font size for your LaTeX
 document, use '"" 12' as options. The font name is ignored. If using
 `standalone` the given font and font size are used, see below for a
 detailed description.

 If text is printed coloured is controlled by the TeX booleans \ifGPcolor
 and \ifGPblacktext. Only if \ifGPcolor is true and \ifGPblacktext is
 false, text is printed coloured. You may either change them in the
 generated TeX file or provide them globally in your TeX file, for example
 by using
    \newif\ifGPblacktext
    \GPblacktexttrue
 in the preamble of your document. The local assignment is only done if no
 global value is given.

 When using the epslatex terminal give the name of the TeX file in the
 `set output` command including the file extension (normally ".tex").
 The eps filename is generated by replacing the extension by ".eps".

 If using the `standalone` mode a complete LaTeX header is added to the
 LaTeX file; and "-inc" is added to the filename of the eps file.
 The `standalone` mode generates a TeX file that produces
 output with the correct size when using dvips, pdfTeX, or VTeX.
 The default, `input`, generates a file that has to be included into a
 LaTeX document using the \input command.

 If a font other than "" or "default" is given it is interpreted as
 LaTeX font name.  It contains up to three parts, separated by a comma:
 'fontname,fontseries,fontshape'.  If the default fontshape or fontseries
 are requested, they can be omitted.  Thus, the real syntax for the fontname
 is '[fontname][,fontseries][,fontshape]'.  The naming convention for all
 parts is given by the LaTeX font scheme.  The fontname is 3 to 4 characters
 long and is built as follows: One character for the font vendor, two
 characters for the name of the font, and optionally one additional
 character for special fonts, e.g., 'j' for fonts with old-style numerals
 or 'x' for expert fonts. The names of many fonts is described in
           http://www.tug.org/fontname/fontname.pdf
 For example, 'cmr' stands for Computer Modern Roman, 'ptm' for Times-Roman,
 and 'phv' for Helvetica.  The font series denotes the thickness of the
 glyphs, in most cases 'm' for normal ("medium") and 'bx' or 'b' for bold
 fonts.  The font shape is 'n' for upright, 'it' for italics, 'sl' for
 slanted, or 'sc' for small caps, in general.  Some fonts may provide
 different font series or shapes.

 Examples:

 Use Times-Roman boldface (with the same shape as in the surrounding text):
       set terminal epslatex 'ptm,bx'
 Use Helvetica, boldface, italics:
       set terminal epslatex 'phv,bx,it'
 Continue to use the surrounding font in slanted shape:
       set terminal epslatex ',,sl'
 Use small capitals:
       set terminal epslatex ',,sc'

 By this method, only text fonts are changed. If you also want to change
 the math fonts you have to use the "gnuplot.cfg" file or the `header`
 option, described below.

 In standalone mode, the font size is taken from the given font size in the
 `set terminal` command. To be able to use a specified font size, a file
 "size<size>.clo" has to reside in the LaTeX search path.  By default,
 10pt, 11pt, and 12pt are supported.  If the package "extsizes" is
 installed, 8pt, 9pt, 14pt, 17pt, and 20pt are added.

 The `header` option takes a string as argument.  This string is written
 into the generated LaTeX file.  If using the `standalone` mode, it is 
 written into the preamble, directly before the \begin{document} command.
 In the `input` mode, it is placed directly after the \begingroup command
 to ensure that all settings are local to the plot.

 Examples:

 Use T1 fontencoding, change the text and math font to Times-Roman as well
 as the sans-serif font to Helvetica:
     set terminal epslatex standalone header \
     "\\usepackage[T1]{fontenc}\n\\usepackage{mathptmx}\n\\usepackage{helvet}"
 Use a boldface font in the plot, not influencing the text outside the plot:
     set terminal epslatex input header "\\bfseries"

 If the file "gnuplot.cfg" is found by LaTeX it is input in the preamble
 the LaTeX document, when using `standalone` mode.  It can be used for
 further settings, e.g., changing the document font to Times-Roman,
 Helvetica, and Courier, including math fonts (handled by "mathptmx.sty"):
       \usepackage{mathptmx}
       \usepackage[scaled=0.92]{helvet}
       \usepackage{courier}
 The file "gnuplot.cfg" is loaded before the header information given
 by the `header` command.  Thus, you can use `header` to overwrite some of
 settings performed using "gnuplot.cfg"

?commands set terminal pslatex
?set terminal pslatex
?set term pslatex
?terminal pslatex
?term pslatex
?pslatex
?commands set terminal pstex
?set terminal pstex
?set term pstex
?terminal pstex
?term pstex
?pstex
 The `pslatex` driver generates output for further processing by LaTeX,
 while the `pstex` driver generates output for further processing by
 TeX. `pslatex` uses \specials understandable by dvips and xdvi. Figures
 generated by `pstex` can be included in any plain-based format (including
 LaTeX).

 Syntax:
       set terminal [pslatex | pstex] {default}
       set terminal [pslatex | pstex]
                               {rotate | norotate}
                               {oldstyle | newstyle}
                               {auxfile | noauxfile}
                               {level1 | leveldefault}
                               {color | colour | monochrome}
                               {background <rgbcolor> | nobackground}
                               {solid | dashed}
                               {dashlength | dl <DL>}
                               {linewidth | lw <LW>}
                               {rounded | butt}
                               {clip | noclip}
                               {palfuncparam <samples>{,<maxdeviation>}}
                               {size <XX>{unit},<YY>{unit}}
                               {<font_size>}

 If you see the error message
       "Can't find PostScript prologue file ... "
 Please see and follow the instructions in `postscript prologue`.

 The option `color` enables color, while `monochrome` prefers black and white
 drawing elements. Further, `monochrome` uses gray `palette` but it does not
 change color of objects specified with an explicit `colorspec`.
 `solid` draws all plots with solid lines, overriding any dashed patterns.
 `dashlength` or `dl` scales the length of the dashed-line segments by <DL>,
 which is a floating-point number greater than zero.
 `linewidth` or `lw` scales all linewidths by <LW>.

 By default the generated PostScript code uses language features that were
 introduced in PostScript Level 2, notably filters and pattern-fill of
 irregular objects such as filledcurves.  PostScript Level 2 features are
 conditionally protected so that PostScript Level 1 interpreters do not issue
 errors but, rather, display a message or a PostScript Level 1 approximation.
 The `level1` option substitutes PostScript Level 1 approximations of these
 features and uses no PostScript Level 2 code.  This may be required by some
 old printers and old versions of Adobe Illustrator.  The flag `level1` can be
 toggled later by editing a single line in the PostScript output file to force
 PostScript Level 1 interpretation.  In the case of files containing level 2
 code, the above features will not appear or will be replaced by a note when
 this flag is set or when the interpreting program does not indicate that it
 understands level 2 PostScript or higher.

 `rounded` sets line caps and line joins to be rounded; `butt` is the
 default, butt caps and mitered joins.

 `clip` tells PostScript to clip all output to the bounding box;
 `noclip` is the default.

 `palfuncparam` controls how `set palette functions` are encoded as gradients
 in the output. Analytic color component functions (set via
 `set palette functions`) are encoded as linear interpolated gradients in the
 postscript output:  The color component functions are sampled at <samples>
 points and all points are removed from this gradient which can be removed
 without changing the resulting colors by more than <maxdeviation>. For
 almost every useful palette you may safely leave the defaults of
 <samples>=2000 and <maxdeviation>=0.003 untouched.

 The default size for postscript output is 10 inches x 7 inches. The default
 for eps output is 5 x 3.5 inches.  The `size` option changes this to
 whatever the user requests. By default the X and Y sizes are taken to be in
 inches, but other units are possibly (currently only cm). The BoundingBox
 of the plot is correctly adjusted to contain the resized image.
 Screen coordinates always run from 0.0 to 1.0 along the full length of the
 plot edges as specified by the `size` option.
 NB: `this is a change from the previously recommended method of using the
 set size command prior to setting the terminal type`.  The old method left
 the BoundingBox unchanged and screen coordinates did not correspond to the
 actual limits of the plot.

 if `rotate` is specified, the y-axis label is rotated.
 <font_size> is the size (in pts) of the desired font.

 If `auxfile` is specified, it directs the driver to put the PostScript
 commands into an auxiliary file instead of directly into the LaTeX file.
 This is useful if your pictures are large enough that dvips cannot handle
 them.  The name of the auxiliary PostScript file is derived from the name of
 the TeX file given on the `set output` command; it is determined by replacing
 the trailing `.tex` (actually just the final extent in the file name) with
 `.ps` in the output file name, or, if the TeX file has no extension, `.ps`
 is appended.  The `.ps` is included into the `.tex` file by a
 \special{psfile=...} command.  Remember to close the `output file` before
 next plot unless in `multiplot` mode.

 Gnuplot versions prior to version 4.2 generated plots of the size
 5 x 3 inches using the ps(la)tex terminal while the current version generates
 5 x 3.5 inches to be consistent with the postscript eps terminal.  In
 addition, the character width is now estimated to be 60% of the font size
 while the old epslatex terminal used 50%. To reach the old format specify
 the option `oldstyle`.

 The pslatex driver offers a special way of controlling text positioning: 
 (a) If any text string begins with '{', you also need to include a '}' at the
 end of the text, and the whole text will be centered both horizontally
 and vertically by LaTeX.  (b) If the text string begins with '[', you need
 to continue it with: a position specification (up to two out of t,b,l,r),
 ']{', the text itself, and finally, '}'. The text itself may be anything
 LaTeX can typeset as an LR-box. \rule{}{}'s may help for best positioning.

 The options not described here are identical to the `Postscript terminal`.
 Look there if you want to know what they do.

 Examples:
       set term pslatex monochrome dashed rotate       # set to defaults
 To write the PostScript commands into the file "foo.ps":
       set term pslatex auxfile
       set output "foo.tex"; plot ...; set output
 About label positioning:
 Use gnuplot defaults (mostly sensible, but sometimes not really best):
        set title '\LaTeX\ -- $ \gamma $'
 Force centering both horizontally and vertically:
        set label '{\LaTeX\ -- $ \gamma $}' at 0,0
 Specify own positioning (top here):
        set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
 The other label -- account for long ticlabels:
        set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'

 Linewidths and pointsizes may be changed with `set style line`.
?commands set terminal postscript
?set terminal postscript
?set term postscript
?terminal postscript
?term postscript
?postscript
 Several options may be set in the `postscript` driver.

 Syntax:
       set terminal postscript {default}
       set terminal postscript {landscape | portrait | eps}
                               {enhanced | noenhanced}
                               {defaultplex | simplex | duplex}
                               {fontfile [add | delete] "<filename>"
                                | nofontfiles} {{no}adobeglyphnames}
                               {level1 | leveldefault}
                               {color | colour | monochrome}
                               {background <rgbcolor> | nobackground}
                               {solid | dashed}
                               {dashlength | dl <DL>}
                               {linewidth | lw <LW>}
                               {rounded | butt}
                               {clip | noclip}
                               {palfuncparam <samples>{,<maxdeviation>}}
                               {size <XX>{unit},<YY>{unit}}
                               {blacktext | colortext | colourtext}
                               {{font} "fontname{,fontsize}" {<fontsize>}}
                               {fontscale <scale>}
 If you see the error message
       "Can't find PostScript prologue file ... "
 Please see and follow the instructions in `postscript prologue`.


 `landscape` and `portrait` choose the plot orientation.
 `eps` mode generates EPS (Encapsulated PostScript) output, which is just
 regular PostScript with some additional lines that allow the file to be
 imported into a variety of other applications.  (The added lines are
 PostScript comment lines, so the file may still be printed by itself.)  To
 get EPS output, use the `eps` mode and make only one plot per file.  In `eps`
 mode the whole plot, including the fonts, is reduced to half of the default
 size.

 `enhanced` enables enhanced text mode features (subscripts,
 superscripts and mixed fonts). See `enhanced` for more information.
 `blacktext` forces all text to be written in black even in color mode;

 Duplexing in PostScript is the ability of the printer to print on both
 sides of the same sheet of paper.  With `defaultplex`, the default setting
 of the printer is used; with `simplex` only one side is printed; `duplex`
 prints on both sides (ignored if your printer can't do it).

 `"<fontname>"` is the name of a valid PostScript font; and `<fontsize>` is
 the size of the font in PostScript points.
 In addition to the standard postscript fonts, an oblique version of the
 Symbol font, useful for mathematics, is defined. It is called
 "Symbol-Oblique".

 `default` sets all options to their defaults: `landscape`, `monochrome`,
 `dashed`, `dl 1.0`, `lw 1.0`, `defaultplex`, `noenhanced`, "Helvetica" and
 14pt.  Default size of a PostScript plot is 10 inches wide and 7 inches high.
 The option `color` enables color, while `monochrome` prefers black and white
 drawing elements. Further, `monochrome` uses gray `palette` but it does not
 change color of objects specified with an explicit `colorspec`.
 `solid` draws all plots with solid lines, overriding any dashed patterns.
 `dashlength` or `dl` scales the length of the dashed-line segments by <DL>,
 which is a floating-point number greater than zero.
 `linewidth` or `lw` scales all linewidths by <LW>.

 By default the generated PostScript code uses language features that were
 introduced in PostScript Level 2, notably filters and pattern-fill of
 irregular objects such as filledcurves.  PostScript Level 2 features are
 conditionally protected so that PostScript Level 1 interpreters do not issue
 errors but, rather, display a message or a PostScript Level 1 approximation.
 The `level1` option substitutes PostScript Level 1 approximations of these
 features and uses no PostScript Level 2 code.  This may be required by some
 old printers and old versions of Adobe Illustrator.  The flag `level1` can be
 toggled later by editing a single line in the PostScript output file to force
 PostScript Level 1 interpretation.  In the case of files containing level 2
 code, the above features will not appear or will be replaced by a note when
 this flag is set or when the interpreting program does not indicate that it
 understands level 2 PostScript or higher.

 `rounded` sets line caps and line joins to be rounded; `butt` is the
 default, butt caps and mitered joins.

 `clip` tells PostScript to clip all output to the bounding box;
 `noclip` is the default.

 `palfuncparam` controls how `set palette functions` are encoded as gradients
 in the output. Analytic color component functions (set via
 `set palette functions`) are encoded as linear interpolated gradients in the
 postscript output:  The color component functions are sampled at <samples>
 points and all points are removed from this gradient which can be removed
 without changing the resulting colors by more than <maxdeviation>. For
 almost every useful palette you may safely leave the defaults of
 <samples>=2000 and <maxdeviation>=0.003 untouched.

 The default size for postscript output is 10 inches x 7 inches. The default
 for eps output is 5 x 3.5 inches.  The `size` option changes this to
 whatever the user requests. By default the X and Y sizes are taken to be in
 inches, but other units are possibly (currently only cm). The BoundingBox
 of the plot is correctly adjusted to contain the resized image.
 Screen coordinates always run from 0.0 to 1.0 along the full length of the
 plot edges as specified by the `size` option.
 NB: `this is a change from the previously recommended method of using the
 set size command prior to setting the terminal type`.  The old method left
 the BoundingBox unchanged and screen coordinates did not correspond to the
 actual limits of the plot.

 Fonts listed by `fontfile` or `fontfile add` encapsulate the font
 definitions of the listed font from a postscript Type 1 or TrueType font
 file directly into the gnuplot output postscript file.  Thus, the enclosed
 font can be used in labels, titles, etc.  See the section
 `postscript fontfile` for more details.  With `fontfile delete`, a fontfile
 is deleted from the list of embedded files.  `nofontfiles` cleans the list
 of embedded fonts.

 Examples:
       set terminal postscript default       # old postscript
       set terminal postscript enhanced      # old enhpost
       set terminal postscript landscape 22  # old psbig
       set terminal postscript eps 14        # old epsf1
       set terminal postscript eps 22        # old epsf2
       set size 0.7,1.4; set term post portrait color "Times-Roman" 14
       set term post "VAGRoundedBT_Regular" 14 fontfile "bvrr8a.pfa"

 Linewidths and pointsizes may be changed with `set style line`.

 The `postscript` driver supports about 70 distinct pointtypes, selectable
 through the `pointtype` option on `plot` and `set style line`.

 Several possibly useful files about `gnuplot`'s PostScript are included
 in the /docs/psdoc subdirectory of the `gnuplot` distribution and at the
 distribution sites.  These are "ps_symbols.gpi" (a `gnuplot` command file
 that, when executed, creates the file "ps_symbols.ps" which shows all the
 symbols available through the `postscript` terminal), "ps_guide.ps" (a
 PostScript file that contains a summary of the enhanced syntax and a page
 showing what the octal codes produce with text and symbol fonts),
 "ps_file.doc" (a text file that contains a discussion of the organization
 of a PostScript file written by `gnuplot`), and "ps_fontfile_doc.tex"
 (a LaTeX file which contains a short documentation concerning the
 encapsulation of LaTeX fonts with a glyph table of the math fonts).

 A PostScript file is editable, so once `gnuplot` has created one, you are
 free to modify it to your heart's desire.  See the `editing postscript`
 section for some hints.
?commands set terminal postscript editing
?set terminal postscript editing
?set term postscript editing
?terminal postscript editing
?term postscript editing
?editing_postscript
?editing postscript
 The PostScript language is a very complex language---far too complex to
 describe in any detail in this document.  Nevertheless there are some things
 in a PostScript file written by `gnuplot` that can be changed without risk of
 introducing fatal errors into the file.

 For example, the PostScript statement "/Color true def" (written into the
 file in response to the command `set terminal postscript color`), may be
 altered in an obvious way to generate a black-and-white version of a plot.
 Similarly line colors, text colors, line weights and symbol sizes can also be
 altered in straight-forward ways.  Text (titles and labels) can be edited to
 correct misspellings or to change fonts.  Anything can be repositioned, and
 of course anything can be added or deleted, but modifications such as these
 may require deeper knowledge of the PostScript language.

 The organization of a PostScript file written by `gnuplot` is discussed in
 the text file "ps_file.doc" in the docs/ps subdirectory of the gnuplot
 source distribution.
?commands set terminal postscript fontfile
?set terminal postscript fontfile
?set term postscript fontfile
?terminal postscript fontfile
?term postscript fontfile
?postscript fontfile
?fontfile
 The `fontfile` or `fontfile add` option takes one file name as argument
 and encapsulates this file into the postscript output in order to make
 this font available for text elements (labels, tic marks, titles, etc.).
 The `fontfile delete` option also takes one file name as argument. It
 deletes this file name from the list of encapsulated files.

 The postscript terminal understands some
 font file formats: Type 1 fonts in ASCII file format (extension ".pfa"),
 Type 1 fonts in binary file format (extension ".pfb"), and TrueType
 fonts (extension ".ttf"). Pfa files are understood directly, pfb and ttf
 files are converted on the fly if appropriate conversion tools are
 installed (see below). You have to specify the full filename including the
 extension. Each `fontfile` option takes exact one font file name. This
 option can be used multiple times in order to include more than one font
 file.

 The font file is searched in the working directory and in all directories
 listed in the fontpath which is determined by `set fontpath`.
 In addition, the fontpath can be set using the environment variable
 GNUPLOT_FONTPATH. If this is not set a system dependent default search
 list is used. See `set fontpath` for more details.

 For using the encapsulated font file you have to specify the font name
 (which normally is not the same as the file name). When embedding a
 font file by using the `fontfile` option in interactive mode, the 
 font name is printed on the screen. E.g.
    Font file 'p052004l.pfb' contains the font 'URWPalladioL-Bold'. Location:
    /usr/lib/X11/fonts/URW/p052004l.pfb

 When using pfa or pfb fonts, you can also find it out by looking into the
 font file. There is a line similar to "/FontName /URWPalladioL-Bold def".
 The middle string without the slash is the fontname, here
 "URWPalladioL-Bold".
 For TrueType fonts, this is not so easy since the font name is stored in a
 binary format. In addition, they often have spaces in the font names which
 is not supported by Type 1 fonts (in which a TrueType is converted on the
 fly). The font names are changed in order to eliminate the spaces in the
 fontnames. The easiest way to find out which font name is generated for
 use with gnuplot, start gnuplot in interactive mode and type in
 "set terminal postscript fontfile '<filename.ttf>'".

 For converting font files (either ttf or pfb) to pfa format, the conversion
 tool has to read the font from a file and write it to standard output. If
 the output cannot be written to standard output, on-the-fly conversion is
 not possible.

 For pfb files "pfbtops" is a tool which can do this. If this program
 is installed on your system the on the fly conversion should work.
 Just try to encapsulate a pfb file. If the compiled in program call does
 not work correctly you can specify how this program is called by
 defining the environment variable GNUPLOT_PFBTOPFA e.g. to
 "pfbtops %s". The `%s` will be replaced by the font file name and thus
 has to exist in the string.

 If you don't want to do the conversion on the fly but get a pfa file of
 the font you can use the tool "pfb2pfa" which is written in simple c
 and should compile with any c compiler.
 It is available from many ftp servers, e.g.
           ftp://ftp.dante.de/tex-archive/fonts/utilities/ps2mf/
 In fact, "pfbtopfa" and "pfb2ps" do the same job. "pfbtopfa" puts
 the resulting pfa code into a file, whereas "pfbtops" writes it to
 standard output.

 TrueType fonts are converted into Type 1 pfa format, e.g.
 by using the tool "ttf2pt1" which is available from
           http://ttf2pt1.sourceforge.net/
 If the builtin conversion does not
 work, the conversion command can be changed by the environment variable
 GNUPLOT_TTFTOPFA. For usage with ttf2pt1 it may be set to
 "ttf2pt1 -a -e -W 0 %s - ". Here again, `%s` stands for the
 file name.

 For special purposes you also can use a pipe (if available for your
 operating system). Therefore you start the file name definition with 
 the character "<" and append a program call. This program has 
 to write pfa data to standard output. Thus, a pfa file may be accessed
 by `set fontfile "< cat garamond.pfa"`.

 For example, including Type 1 font files can be used for including the
 postscript output in LaTeX documents. The "european computer modern"
 font (which is a variant of the "computer modern" font) is available
 in pfb format from any CTAN server, e.g.
           ftp://ftp.dante.de/tex-archive/fonts/ps-type1/cm-super/
 For example, the file "sfrm1000.pfb" contains the normal upright fonts
 with serifs in the design size 10pt (font name "SFRM1000").
 The computer modern fonts, which are still necessary for mathematics,
 are available from
           ftp://ftp.dante.de/tex-archive/fonts/cm/ps-type1/bluesky
 With these you can use any character available in TeX. However, the
 computer modern fonts have a strange encoding. (This is why you should not
 use cmr10.pfb for text, but sfrm1000.pfb instead.)
 The usage of TeX fonts is shown in one of the demos.
 The file "ps_fontfile_doc.tex" in the /docs/psdoc subdirectory of the
 `gnuplot` source distribution contains a table with glyphs of the TeX
 mathfonts.

 If the font "CMEX10" is embedded (file "cmex10.pfb") gnuplot defines
 the additional font "CMEX10-Baseline". It is shifted vertically in order
 to fit better to the other glyphs (CMEX10 has its baseline at the top of
 the symbols).
?commands set terminal postscript prologue
?set terminal postscript prologue
?terminal postscript prologue
?postscript prologue
?prologue
 Each PostScript output file includes a %%Prolog section and possibly some
 additional user-defined sections containing, for example, character encodings.
 These sections are copied from a set of PostScript prologue files that are
 either compiled into the gnuplot executable or stored elsewhere on your
 computer. A default directory where these files live is set at the time
 gnuplot is built. However, you can override this default either by using the
 gnuplot command `set psdir` or by defining an environment variable
 GNUPLOT_PS_DIR. See `set psdir`.
?commands set terminal postscript adobeglyphnames
?set terminal postscript adobeglyphnames
?terminal postscript adobeglyphnames
?postscript adobeglyphnames
?adobeglyphnames
 This setting is only relevant to PostScript output with UTF-8 encoding.
 It controls the names used to describe characters with Unicode entry points
 higher than 0x00FF.  That is, all characters outside of the Latin1 set.
 In general unicode characters do not have a unique name; they have only a
 unicode identification code.  However, Adobe have a recommended scheme for
 assigning names to certain ranges of characters (extended Latin, Greek, etc).
 Some fonts use this scheme, others do not.  By default, gnuplot will use
 the Adobe glyph names.  E.g. the lower case Greek letter alpha will be called
 /alpha.  If you specific `noadobeglyphnames` then instead gnuplot will use
 /uni03B1 to describe this character.  If you get this setting wrong, the
 character may not be found even if it is present in the font.
 It is probably always correct to use the default for Adobe fonts, but for
 other fonts you may have to try both settings.  See also `fontfile`.


?commands set terminal qms
?set terminal qms
?set term qms
?terminal qms
?term qms
?qms
 The `qms` terminal driver supports the QMS/QUIC Laser printer, the Talaris
 1200 and others.  It has no options.
?commands set terminal svg
?set terminal svg
?set term svg
?terminal svg
?term svg
?svg
 This terminal produces files in the W3C Scalable Vector Graphics format.

 Syntax:
       set terminal svg {size <x>,<y> {|fixed|dynamic}}
                        {{no}enhanced}
                        {fname "<font>"} {fsize <fontsize>}
                        {mouse} {standalone | jsdir <dirname>}
                        {name <plotname>}
                        {font "<fontname>{,<fontsize>}"}
                        {fontfile <filename>}
                        {rounded|butt} {solid|dashed} {linewidth <lw>}
                        {background <rgb_color>}

 where <x> and <y> are the size of the SVG plot to generate,
 `dynamic` allows a svg-viewer to resize plot, whereas the default
 setting, `fixed`, will request an absolute size.

 `linewidth <w>` increases the width of all lines used in the figure
 by a factor of <w>.

 <font> is the name of the default font to use (default Arial) and
 <fontsize> is the font size (in points, default 12). SVG viewing
 programs may substitute other fonts when the file is displayed.

 The svg terminal supports an enhanced text mode, which allows font
 and other formatting commands to be embedded in labels and other text
 strings. The enhanced text mode syntax is shared with other gnuplot
 terminal types. See `enhanced` for more details.

 The `mouse` option tells gnuplot to add support for mouse tracking and for
 toggling individual plots on/off by clicking on the corresponding key entry.
 By default this is done by including a link that points to a script in a
 local directory, usually /usr/local/share/gnuplot/<version>/js.
 You can change this by using the `jsdir` option to specify either a
 different local directory or a general URL. The latter is usually
 appropriate if you are embedding the svg into a web page.
 Alternatively, the `standalone` option embeds the mousing code in the
 svg document itself rather than linking to an external resource.

 When an SVG file will be used in conjunction with external files,
 e.g. if it embeds a PNG image or is referenced by javascript code
 in a web page or embedding document, then a unique name is required
 to avoid potential conflicting references to other SVG plots.
 Use the `name` option to ensure uniqueness.

 SVG allows you to embed fonts directly into an SVG document, or to
 provide a hypertext link to the desired font. The `fontfile` option
 specifies a local file which is copied into the <defs> section of the
 resulting SVG output file.  This file may either itself contain a font,
 or may contain the records necessary to create a hypertext reference to
 the desired font. Gnuplot will look for the requested file using the
 directory list in the GNUPLOT_FONTPATH environmental variable.
 NB: You must embed an svg font, not a TrueType or PostScript font.
?commands set terminal tgif
?set terminal tgif
?set term tgif
?terminal tgif
?term tgif
?tgif
 Tgif is an X11-based drawing tool---it has nothing to do with GIF.

 The `tgif` driver supports different pointsizes (with `set pointsize`),
 different label fonts and font sizes (e.g. `set label "Hallo" at x,y font
 "Helvetica,34"`) and multiple graphs on the page.  The proportions of the
 axes are not changed.

 Syntax:
       set terminal tgif {portrait | landscape | default} {<[x,y]>}
                         {monochrome | color}
                         {{linewidth | lw} <LW>}
                         {solid | dashed}
                         {font "<fontname>{,<fontsize>}"}

 where <[x,y]> specifies the number of graphs in the x and y directions on the
 page, `color` enables color, `linewidth` scales all linewidths by <LW>,
 "<fontname>" is the name of a valid PostScript font, and <fontsize>
 specifies the size of the PostScript font.
 `defaults` sets all options to their defaults: `portrait`, `[1,1]`, `color`,
 `linwidth 1.0`, `dashed`, `"Helvetica,18"`.

 The `solid` option is usually prefered if lines are colored, as they often
 are in the editor.  Hardcopy will be black-and-white, so `dashed` should be
 chosen for that.

 Multiplot is implemented in two different ways.

 The first multiplot implementation is the standard gnuplot multiplot feature:

       set terminal tgif
       set output "file.obj"
       set multiplot
       set origin x01,y01
       set size  xs,ys
       plot ...
            ...
       set origin x02,y02
       plot ...
       unset multiplot

 See `set multiplot` for further information.

 The second version is the [x,y] option for the driver itself.  The advantage
 of this implementation is that everything is scaled and placed automatically
 without the need for setting origins and sizes; the graphs keep their natural
 x/y proportions of 3/2 (or whatever is fixed by `set size`).

 If both multiplot methods are selected, the standard method is chosen and a
 warning message is given.

 Examples of single plots (or standard multiplot):
       set terminal tgif                  # defaults
       set terminal tgif "Times-Roman,24"
       set terminal tgif landscape
       set terminal tgif landscape solid

 Examples using the built-in multiplot mechanism:
       set terminal tgif portrait [2,4]  # portrait; 2 plots in the x-
                                         # and 4 in the y-direction
       set terminal tgif [1,2]           # portrait; 1 plot in the x-
                                         # and 2 in the y-direction
       set terminal tgif landscape [3,3] # landscape; 3 plots in both
                                         # directions
?commands set terminal tkcanvas
?set terminal tkcanvas
?set term tkcanvas
?terminal tkcanvas
?term tkcanvas
?tkcanvas
 This terminal driver generates Tk canvas widget commands based on Tcl/Tk
 (default) or Perl.  To use it, rebuild `gnuplot` (after uncommenting or
 inserting the appropriate line in "term.h"), then

  gnuplot> set term tkcanvas {perltk} {interactive}
  gnuplot> set output 'plot.file'

 After invoking "wish", execute the following sequence of Tcl/Tk commands:

  % source plot.file
  % canvas .c
  % pack .c
  % gnuplot .c

 Or, for Perl/Tk use a program like this:

  use Tk;
  my $top = MainWindow->new;
  my $c = $top->Canvas->pack;
  my $gnuplot = do "plot.pl";
  $gnuplot->($c);
  MainLoop;

 The code generated by `gnuplot` creates a procedure called "gnuplot"
 that takes the name of a canvas as its argument.  When the procedure is
 called, it clears the canvas, finds the size of the canvas and draws the plot
 in it, scaled to fit.

 For 2-dimensional plotting (`plot`) two additional procedures are defined:
 "gnuplot_plotarea" will return a list containing the borders of the plotting
 area "xleft, xright, ytop, ybot" in canvas screen coordinates, while the ranges
 of the two axes "x1min, x1max, y1min, y1max, x2min, x2max, y2min, y2max" in plot
 coordinates can be obtained calling "gnuplot_axisranges".
 If the "interactive" option is specified, mouse clicking on a line segment
 will print the coordinates of its midpoint to stdout. Advanced actions
 can happen instead if the user supplies a procedure named
 "user_gnuplot_coordinates", which takes the following arguments:
 "win id x1s y1s x2s y2s x1e y1e x2e y2e x1m y1m x2m y2m",
 the name of the canvas and the id of the line segment followed by the
 coordinates of its start and end point in the two possible axis ranges; the
 coordinates of the midpoint are only filled for logarithmic axes.

 The current version of `tkcanvas` supports neither `multiplot` nor `replot`.
?commands set terminal emtex
?set terminal emtex
?set term emtex
?terminal emtex
?term emtex
?emtex
?commands set terminal latex
?set terminal latex
?set term latex
?terminal latex
?term latex
?latex
 Syntax:
       set terminal {latex | emtex} {default | {courier|roman} {<fontsize>}}
                    {size <XX>{unit}, <YY>{unit}} {rotate | norotate}

 By default the plot will inherit font settings from the embedding document.
 You have the option of forcing either Courier (cmtt) or Roman (cmr) fonts
 instead. In this case you may also specify a fontsize.
 Unless your driver is capable of building fonts at any size (e.g. dvips),
 stick to the standard 10, 11 and 12 point sizes.

 METAFONT users beware: METAFONT does not like odd sizes.

 All drivers for LaTeX offer a special way of controlling text positioning:
 If any text string begins with '{', you also need to include a '}' at the
 end of the text, and the whole text will be centered both horizontally and
 vertically.  If the text string begins with '[', you need to follow this with
 a position specification (up to two out of t,b,l,r), ']{', the text itself,
 and finally '}'.  The text itself may be anything LaTeX can typeset as an
 LR-box.  '\rule{}{}'s may help for best positioning.

 Points, among other things, are drawn using the LaTeX commands "\Diamond" and
 "\Box".  These commands no longer belong to the LaTeX2e core; they are included
 in the latexsym package, which is part of the base distribution and thus part
 of any LaTeX implementation.  Please do not forget to use this package.
 Other point types use symbols from the amssymb package.

 The default size for the plot is 5 inches by 3 inches. The `size` option
 changes this to whatever the user requests. By default the X and Y sizes
 are taken to be in inches, but other units are possible (currently only cm).

 If 'rotate' is specified, rotated text, especially a rotated y-axis label,
 is possible (the packages graphics or graphicx are needed). The 'stacked'
 y-axis label mechanism is then deactivated.

 Examples:
 About label positioning:
 Use gnuplot defaults (mostly sensible, but sometimes not really best):
        set title '\LaTeX\ -- $ \gamma $'
 Force centering both horizontally and vertically:
        set label '{\LaTeX\ -- $ \gamma $}' at 0,0
 Specify own positioning (top here):
        set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
 The other label -- account for long ticlabels:
        set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'
?commands set terminal eepic
?set terminal eepic
?set term eepic
?terminal eepic
?term eepic
?eepic
 The `eepic` terminal driver supports the extended LaTeX picture environment.
 It is an alternative to the `latex` driver.

 The output of this terminal is intended for use with the "eepic.sty" macro
 package for LaTeX.  To use it, you need "eepic.sty", "epic.sty" and a
 printer driver that supports the "tpic" \specials.  If your printer driver
 doesn't support those \specials, "eepicemu.sty" will enable you to use some
 of them.
 dvips and dvipdfm do support the "tpic" \specials.

 Syntax:
    set terminal eepic {default} {color|dashed} {rotate} {size XX,YY}
                       {small|tiny|<fontsize>}

 Options:
 You can give options in any order you wish.
 'color' causes gnuplot to produce \color{...} commands so that the graphs are
 colored. Using this option, you must include \usepackage{color} in the preambel
 of your latex document.
 'dashed' will allow dashed line types; without this option, only solid lines
 with varying thickness will be used.
 'dashed' and 'color' are mutually exclusive; if 'color' is specified, then
 'dashed' will be ignored.
 'rotate' will enable true rotated text (by 90 degrees). Otherwise, rotated text
 will be typeset with letters stacked above each other. If you use this option
 you must include \usepackage{graphicx} in the preamble.
 'small' will use \scriptsize symbols as point markers (Probably does not work
 with TeX, only LaTeX2e). Default is to use the default math size.
 'tiny' uses \scriptscriptstyle symbols.
 'default' resets all options to their defaults = no color, no dashed lines,
 pseudo-rotated (stacked) text, large point symbols.
 <fontsize> is a number which specifies the font size inside the picture
 environment; the unit is pt (points), i.e., 10 pt equals approx. 3.5 mm.
 If fontsize is not specified, then all text inside the picture will be set
 in \footnotesize.

 Notes:
 Remember to escape the # character (or other chars meaningful to (La-)TeX)
 by \\ (2 backslashes).
 It seems that dashed lines become solid lines when the vertices of a plot
 are too close. (I do not know if that is a general problem with the tpic
 specials, or if it is caused by a bug in eepic.sty or dvips/dvipdfm.)
 The default size of an eepic plot is 5x3 inches. You can change this using 
 the `size` terminal option.
 Points, among other things, are drawn using the LaTeX commands "\Diamond",
 "\Box", etc.  These commands no longer belong to the LaTeX2e core; they are
 included in the latexsym package, which is part of the base distribution and
 thus part of any LaTeX implementation. Please do not forget to use this package.
 Instead of latexsym, you can also include the amssymb package.
 All drivers for LaTeX offer a special way of controlling text positioning:
 If any text string begins with '{', you also need to include a '}' at the
 end of the text, and the whole text will be centered both horizontally and
 vertically.  If the text string begins with '[', you need to follow this with
 a position specification (up to two out of t,b,l,r), ']{', the text itself,
 and finally '}'.  The text itself may be anything LaTeX can typeset as an
 LR-box.  '\rule{}{}'s may help for best positioning.

 Examples:
 set term eepic
   output graphs as eepic macros inside a picture environment;
   \input the resulting file in your LaTeX document.
 set term eepic color tiny rotate 8
   eepic macros with \color macros, \scripscriptsize point markers,
   true rotated text, and all text set with 8pt.

 About label positioning:
 Use gnuplot defaults (mostly sensible, but sometimes not really best):
        set title '\LaTeX\ -- $ \gamma $'
 Force centering both horizontally and vertically:
        set label '{\LaTeX\ -- $ \gamma $}' at 0,0
 Specify own positioning (top here):
        set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
 The other label -- account for long ticlabels:
        set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'
?commands set terminal tpic
?set terminal tpic
?set term tpic
?terminal tpic
?term tpic
?tpic
 The `tpic` terminal driver supports the LaTeX picture environment with tpic
 \specials.  It is an alternative to the `latex` and `eepic` terminal drivers.
 Options are the point size, line width, and dot-dash interval.

 Syntax:
       set terminal tpic <pointsize> <linewidth> <interval>

 where `pointsize` and `linewidth` are integers in milli-inches and `interval`
 is a float in inches.  If a non-positive value is specified, the default is
 chosen: pointsize = 40, linewidth = 6, interval = 0.1.

 All drivers for LaTeX offer a special way of controlling text positioning:
 If any text string begins with '{', you also need to include a '}' at the
 end of the text, and the whole text will be centered both horizontally
 and vertically by LaTeX. --- If the text string begins with '[', you need
 to continue it with: a position specification (up to two out of t,b,l,r),
 ']{', the text itself, and finally, '}'. The text itself may be anything
 LaTeX can typeset as an LR-box. \rule{}{}'s may help for best positioning.

 Examples:
 About label positioning:
 Use gnuplot defaults (mostly sensible, but sometimes not really best):
        set title '\LaTeX\ -- $ \gamma $'
 Force centering both horizontally and vertically:
        set label '{\LaTeX\ -- $ \gamma $}' at 0,0
 Specify own positioning (top here):
        set xlabel '[t]{\LaTeX\ -- $ \gamma $}'
 The other label -- account for long ticlabels:
        set ylabel '[r]{\LaTeX\ -- $ \gamma $\rule{7mm}{0pt}}'
?commands set terminal pstricks
?set terminal pstricks
?set term pstricks
?terminal pstricks
?term pstricks
?pstricks
 The `pstricks` driver is intended for use with the "pstricks.sty" macro
 package for LaTeX.  It is an alternative to the `eepic` and `latex` drivers.
 You need "pstricks.sty", and, of course, a printer that understands
 PostScript, or a converter such as Ghostscript.

 PSTricks is available via anonymous ftp from the /pub directory at
 Princeton.edu.  This driver definitely does not come close to using the full
 capability of the PSTricks package.

 Syntax:
       set terminal pstricks {hacktext | nohacktext} {unit | nounit}

 The first option invokes an ugly hack that gives nicer numbers; the second
 has to do with plot scaling.  The defaults are `hacktext` and `nounit`.
?commands set terminal texdraw
?set terminal texdraw
?set term texdraw
?terminal texdraw
?term texdraw
?texdraw
 The `texdraw` terminal driver supports the LaTeX texdraw environment.  It is
 intended for use with "texdraw.sty" and "texdraw.tex" in the texdraw package.

 Points, among other things, are drawn using the LaTeX commands "\Diamond" and
 "\Box".  These commands no longer belong to the LaTeX2e core; they are included
 in the latexsym package, which is part of the base distribution and thus part
 of any LaTeX implementation.  Please do not forget to use this package.

 It has no options.
?commands set terminal mf
?set terminal mf
?set term mf
?terminal mf
?term mf
?mf
?metafont
 The `mf` terminal driver creates an input file to the METAFONT program.  Thus a
 figure may be used in the TeX document in the same way as is a character.

 To use a picture in a document, the METAFONT program must be run with the
 output file from `gnuplot` as input.  Thus, the user needs a basic knowledge
 of the font creating process and the procedure for including a new font in a
 document.  However, if the METAFONT program is set up properly at the local
 site, an unexperienced user could perform the operation without much trouble.

 The text support is based on a METAFONT character set.  Currently the
 Computer Modern Roman font set is input, but the user is in principal free to
 choose whatever fonts he or she needs.  The METAFONT source files for the
 chosen font must be available.  Each character is stored in a separate
 picture variable in METAFONT.  These variables may be manipulated (rotated,
 scaled etc.) when characters are needed.  The drawback is the interpretation
 time in the METAFONT program.  On some machines (i.e. PC) the limited amount
 of memory available may also cause problems if too many pictures are stored.

 The `mf` terminal has no options.
?commands set terminal mf detailed
?set terminal mf detailed
?set term mf detailed
?mf detailed
?metafont detailed

 - Set your terminal to METAFONT:
   set terminal mf
 - Select an output-file, e.g.:
   set output "myfigures.mf"
 - Create your pictures. Each picture will generate a separate character. Its
 default size will be 5*3 inches. You can change the size by saying `set size
 0.5,0.5` or whatever fraction of the default size you want to have.

 - Quit `gnuplot`.

 - Generate a TFM and GF file by running METAFONT on the output of `gnuplot`.
 Since the picture is quite large (5*3 in), you will have to use a version of
 METAFONT that has a value of at least 150000 for memmax.  On Unix systems
 these are conventionally installed under the name bigmf.  For the following
 assume that the command virmf stands for a big version of METAFONT.  For
 example:

 - Invoke METAFONT:
     virmf '&plain'
 - Select the output device: At the METAFONT prompt ('*') type:
     \mode:=CanonCX;     % or whatever printer you use
 - Optionally select a magnification:
     mag:=1;             % or whatever you wish
 - Input the `gnuplot`-file:
     input myfigures.mf
 On a typical Unix machine there will usually be a script called "mf" that
 executes virmf '&plain', so you probably can substitute mf for virmf &plain.
 This will generate two files: mfput.tfm and mfput.$$$gf (where $$$ indicates
 the resolution of your device).  The above can be conveniently achieved by
 typing everything on the command line, e.g.:
 virmf '&plain' '\mode:=CanonCX; mag:=1; input myfigures.mf'
 In this case the output files will be named myfigures.tfm and
 myfigures.300gf.

 - Generate a PK file from the GF file using gftopk:
   gftopk myfigures.300gf myfigures.300pk
 The name of the output file for gftopk depends on the DVI driver you use.
 Ask your local TeX administrator about the naming conventions.  Next, either
 install the TFM and PK files in the appropriate directories, or set your
 environment variables properly.  Usually this involves setting TEXFONTS to
 include the current directory and doing the same thing for the environment
 variable that your DVI driver uses (no standard name here...).  This step is
 necessary so that TeX will find the font metric file and your DVI driver will
 find the PK file.

 - To include your pictures in your document you have to tell TeX the font:
   \font\gnufigs=myfigures
 Each picture you made is stored in a single character.  The first picture is
 character 0, the second is character 1, and so on...  After doing the above
 step, you can use the pictures just like any other characters.  Therefore, to
 place pictures 1 and 2 centered in your document, all you have to do is:
   \centerline{\gnufigs\char0}
   \centerline{\gnufigs\char1}
 in plain TeX.  For LaTeX you can, of course, use the picture environment and
 place the picture wherever you wish by using the \makebox and \put macros.

 This conversion saves you a lot of time once you have generated the font;
 TeX handles the pictures as characters and uses minimal time to place them,
 and the documents you make change more often than the pictures do.  It also
 saves a lot of TeX memory.  One last advantage of using the METAFONT driver
 is that the DVI file really remains device independent, because no \special
 commands are used as in the eepic and tpic drivers.
?commands set terminal mpost
?set terminal mp
?set term mp
?terminal mp
?term mp
?mp
?metapost

 The `mp` driver produces output intended to be input to the Metapost program.
 Running Metapost on the file creates EPS files containing the plots. By
 default, Metapost passes all text through TeX.  This has the advantage of
 allowing essentially  any TeX symbols in titles and labels.

 Syntax:
    set term mp {color | colour | monochrome}
                {solid | dashed}
                {notex | tex | latex}
                {magnification <magsize>}
                {psnfss | psnfss-version7 | nopsnfss}
                {prologues <value>}
                {a4paper}
                {amstex}
                {"<fontname> {,<fontsize>}"} 

 The option `color` causes lines to be drawn in color (on a printer or display
 that supports it), `monochrome` (or nothing) selects black lines.  The option
 `solid` draws solid lines, while `dashed` (or nothing) selects lines with
 different patterns of dashes.  If `solid` is selected but `color` is not,
 nearly all lines will be identical.  This may occasionally be useful, so it is
 allowed.

 The option `notex` bypasses TeX entirely, therefore no TeX code can be used in
 labels under this option.  This is intended for use on old plot files or files
 that make frequent use of common characters like `$` and `%` that require
 special handling in TeX.

 The option `tex` sets the terminal to output its text for TeX to process.

 The option `latex` sets the terminal to output its text for processing by
 LaTeX. This allows things like \frac for fractions which LaTeX knows about
 but TeX does not.  Note that you must set the environment variable TEX to the
 name of your LaTeX executable (normally latex) if you use this option or use
 `mpost --tex=<name of LaTeX executable> ...`. Otherwise metapost will try and
 use TeX to process the text and it won't work.

 Changing font sizes in TeX has no effect on the size of mathematics, and there
 is no foolproof way to make such a change, except by globally  setting a
 magnification factor. This is the purpose of the `magnification` option. It
 must be followed by a scaling factor. All text (NOT the graphs) will be scaled
 by this factor. Use this if you have math that you want at some size other
 than the default 10pt. Unfortunately, all math will be the same size, but see
 the discussion below on editing the MP output. `mag` will also work under
 `notex` but there seems no point in using it as the font size option (below)
 works as well.

 The option `psnfss` uses postscript fonts in combination with LaTeX. Since
 this option only makes sense, if LaTeX is being used, the `latex` option is selected
 automatically. This option includes the following packages for LaTeX:
 inputenc(latin1), fontenc(T1), mathptmx, helvet(scaled=09.2), courier, latexsym 
 and textcomp.

 The option `psnfss-version7` uses also postscript fonts in LaTeX (option `latex`
 is also automatically selected), but uses the following packages with LaTeX:
 inputenc(latin1), fontenc(T1), times, mathptmx, helvet and courier.

 The option `nopsnfss` is the default and uses the standard font (cmr10 if not
 otherwise specified).

 The option `prologues` takes a value as an additional argument and adds the line
 `prologues:=<value>` to the metapost file. If a value of `2` is specified metapost
 uses postscript fonts to generate the eps-file, so that the result can be viewed
 using e.g. ghostscript. Normally the output of metapost uses TeX fonts and therefore
 has to be included in a (La)TeX file before you can look at it.

 The option `noprologues` is the default. No additional line specifying the prologue
 will be added.

 The option `a4paper` adds a `[a4paper]` to the documentclass. Normally letter paper
 is used (default). Since this option is only used in case of LaTeX, the `latex` option
 is selected automatically.

 The option `amstex` automatically selects the `latex` option and includes the following
 LaTeX packages: amsfonts, amsmath(intlimits). By default these packages are not
 included.

 A name in quotes selects the font that will be used when no explicit font is
 given in a `set label` or `set title`.  A name recognized by TeX (a TFM file
 exists) must be used.  The default is "cmr10" unless `notex` is selected,
 then it is "pcrr8r" (Courier).  Even under `notex`, a TFM file is needed by
 Metapost. The file `pcrr8r.tfm` is the name given to Courier in LaTeX's psnfss
 package.  If you change the font from the `notex` default, choose a font that
 matches the ASCII encoding at least in the range 32-126.  `cmtt10` almost
 works, but it has a nonblank character in position 32 (space).

 The size can be any number between 5.0 and 99.99.  If it is omitted, 10.0 is
 used.  It is advisable to use `magstep` sizes: 10 times an integer or
 half-integer power of 1.2, rounded to two decimals, because those are the most
 available sizes of fonts in TeX systems.

 All the options are optional.  If font information is given, it must be at the
 end, with size (if present) last.  The size is needed to select a size for the
 font, even if the font name includes size information.  For example,
 `set term mp "cmtt12"` selects cmtt12 shrunk to the default size 10.  This
 is probably not what you want or you would have used cmtt10.

 The following common ascii characters need special treatment in TeX:
    $, &, #, %, _;  |, <, >;  ^, ~,  \, {, and }
 The five characters $, #, &, _, and % can simply be escaped, e.g., `\$`.
 The three characters <, >, and | can be wrapped in math mode, e.g., `$<$`.
 The remainder require some TeX work-arounds.  Any good book on TeX will give
 some guidance.

 If you type your labels inside double quotes, backslashes in TeX code need to
 be escaped (doubled). Using single quotes will avoid having to do this, but
 then you cannot use `\n` for line breaks.  As of this writing, version 3.7 of
 gnuplot processes titles given in a `plot` command differently than in other
 places, and backslashes in TeX commands need to be doubled regardless of the
 style of quotes.

 Metapost pictures are typically used in TeX documents.  Metapost deals with
 fonts pretty much the same way TeX does, which is different from most other
 document preparation programs.  If the picture is included in a LaTeX document
 using the graphics package, or in a plainTeX document via epsf.tex, and then
 converted to PostScript with dvips (or other dvi-to-ps converter), the text in
 the plot will usually be handled correctly.  However, the text may not appear
 if you send the Metapost output as-is to a PostScript interpreter.

?commands set terminal mp detailed
?set terminal mp detailed
?set term mp detailed
?mp detailed
?metapost detailed

 - Set your terminal to Metapost, e.g.:
    set terminal mp mono "cmtt12" 12

 - Select an output-file, e.g.:
    set output "figure.mp"

 - Create your pictures.  Each plot (or multiplot group) will generate a
 separate Metapost beginfig...endfig group.  Its default size will be 5 by 3
 inches.  You can change the size by saying `set size 0.5,0.5` or whatever
 fraction of the default size you want to have.

 - Quit gnuplot.

 - Generate EPS files by running Metapost on the output of gnuplot:
    mpost figure.mp  OR  mp figure.mp
 The name of the Metapost program depends on the system, typically `mpost` for
 a Unix machine and `mp` on many others.  Metapost will generate one EPS file
 for each picture.

 - To include your pictures in your document you can use the graphics package
 in LaTeX or epsf.tex in plainTeX:
    \usepackage{graphics} % LaTeX
    \input epsf.tex       % plainTeX
 If you use a driver other than dvips for converting TeX DVI output to PS, you
 may need to add the following line in your LaTeX document:
    \DeclareGraphicsRule{*}{eps}{*}{}
 Each picture you made is in a separate file.  The first picture is in, e.g.,
 figure.0, the second in figure.1, and so on....  To place the third picture in
 your document, for example, all you have to do is:
    \includegraphics{figure.2} % LaTeX
    \epsfbox{figure.2}         % plainTeX

 The advantage, if any, of the mp terminal over a postscript terminal is
 editable output.  Considerable effort went into making this output as clean as
 possible.  For those knowledgeable in the Metapost language, the default line
 types and colors can be changed by editing the arrays `lt[]` and `col[]`.
 The choice of solid vs dashed lines, and color vs black lines can be change by
 changing the values assigned to the booleans `dashedlines` and `colorlines`.
 If the default `tex` option was in effect, global changes to the text of
 labels can be achieved by editing the `vebatimtex...etex` block.  In
 particular, a LaTeX preamble can be added if desired, and then LaTeX's
 built-in size changing commands can be used for maximum flexibility. Be sure
 to set the appropriate MP configuration variable to force Metapost to run
 LaTeX instead of plainTeX.
?commands set terminal context
?set terminal context
?terminal context
?set term context
?term context
?context
 ConTeXt is a macro package for TeX, highly integrated with Metapost
 (for drawing figures) and intended for creation of high-quality PDF documents.
 The terminal outputs Metafun source, which can be edited manually,
 but you should be able to configure most things from outside.

 For an average user of ConTeXt + gnuplot module it's recommended to refer to
 `Using ConTeXt` rather than reading this page
 or to read the manual of the gnuplot module for ConTeXt.

 The `context` terminal supports the following options:

 Syntax:
      set term context {default}
              {defaultsize | size <scale> | size <xsize>{in|cm}, <ysize>{in|cm}}
              {input | standalone}
              {timestamp | notimestamp}
              {noheader | header "<header>"}
              {color | colour | monochrome}
              {rounded | mitered | beveled} {round | butt | squared}
              {dashed | solid} {dashlength | dl <dl>}
              {linewidth | lw <lw>}
              {fontscale <fontscale>}
              {mppoints | texpoints}
              {inlineimages | externalimages}
              {defaultfont | font "{<fontname>}{,<fontsize>}"}

 In non-standalone (`input`) graphic only parameters `size` to select graphic
 size, `fontscale` to scale all the labels for a factor <fontscale>
 and font size, make sense, the rest is silently
 ignored and should be configured in the .tex file which inputs the graphic.
 It's highly recommended to set the proper fontsize if document font differs from
 12pt, so that gnuplot will know how much space to reserve for labels.

 `default` resets all the options to their default values.

 `defaultsize` sets the plot size to 5in,3in.
 `size` <scale> sets the plot size to <scale> times <default value>.
 If two arguments are given (separated with ','), the first one sets
 the horizontal size and the second one the vertical size.
 Size may be given without units (in which case it means relative to the default
 value), with inches ('in') or centimeters ('cm').

 `input` (default) creates a graphic that can be included into another ConTeXt
 document.
 `standalone` adds some lines, so that the document might be compiled as-is.
 You might also want to add `header` in that case.

 Use `header` for any additional settings/definitions/macros
 that you might want to include in a standalone graphic. `noheader` is the default.

 `notimestamp` prevents printing creation time in comments
 (if version control is used, one may prefer not to commit new version when only date changes).

 `color` to make color plots is the default, but `monochrome` doesn't do anything special yet.
 If you have any good ideas how the behaviour should differ to suit the monochrome printers better,
 your suggestions are welcome.

 `rounded` (default), `mitered` and `beveled` control the shape of line joins.
 `round` (default), `butt` and `squared` control the shape of line caps.
 See PostScript or PDF Reference Manual for explanation. For wild-behaving functions
 and thick lines
 it is better to use `rounded` and `round` to prevent sharp corners in line joins.
 (Some general support for this should be added to Gnuplot, so that the same options
 could be set for each line (style) separately).

 `dashed` (default) uses different dash patterns for different line types,
 `solid` draws all plots with solid lines.

 `dashlength` or `dl` scales the length of the dashed-line segments by <dl>.
 `linewidth` or `lw` scales all linewidths by <lw>.
 (lw 1 stands for 0.5bp, which is the default line width when drawing with Metapost.)
 `fontscale` scales text labels for factor <fontscale> relative to default document font.

 `mppoints` uses predefined point shapes, drawn in Metapost.
 `texpoints` uses easily configurable set of symbols, defined with ConTeXt
 in the following way:
      \defineconversion[my own points][+,{\ss x},\mathematics{\circ}]
      \setupGNUPLOTterminal[context][points=tex,pointset=my own points]

 `inlineimages` writes binary images to a string and only works in ConTeXt MKIV.
 `externalimages` writes PNG files to disk and also works with ConTeXt MKII.
 Gnuplot needs to have support for PNG images built in for this to work.

 With `font` you can set font name and size in standalone graphics.
 In non-standalone (`input`) mode only the font size is important
 to reserve enough space for text labels.
 The command
      set term context font "myfont,ss,10"
 will result in
      \setupbodyfont[myfont,ss,10pt]
 If you additionaly set `fontscale` to 0.8 for example,
 then the resulting font will be 8pt big and
      set label ... font "myfont,12"
 will come out as 9.6pt.

 It is your own responsibility to provide proper typescripts (and header),
 otherwise switching the font will have no effect.
 For a standard font in ConTeXt MKII (pdfTeX) you could use:
      set terminal context standalone header '\usetypescript[iwona][ec]' \
          font "iwona,ss,11"
 Please take a look into ConTeXt documentation, wiki or mailing list (archives)
 for any up-to-date information about font usage.

 Examples:
      set terminal context size 10cm, 5cm     # 10cm, 5cm
      set terminal context size 4in, 3in      # 4in, 3in
 For standalone (whole-page) plots with labels in UTF-8 encoding:
      set terminal context standalone header '\enableregime[utf-8]'

 You need gnuplot module for ConTeXt
      http://ctan.org/pkg/context-gnuplot
 and a recent version of ConTeXt.
 If you want to call gnuplot on-the-fly, you also need write18 enabled.
 In most TeX distributions this can be set with shell_escape=t in texmf.cnf.

 See
           http://wiki.contextgarden.net/Gnuplot
 for details about this terminal and for more exhaustive help & examples.

 The easiest way to make plots in ConTeXt documents is
      \usemodule[gnuplot]
      \starttext
      \title{How to draw nice plots with {\sc gnuplot}?}
      \startGNUPLOTscript[sin]
      set format y "%.1f"
      plot sin(x) t '$\sin(x)$'
      \stopGNUPLOTscript
      \useGNUPLOTgraphic[sin]
      \stoptext
 This will run gnuplot automatically and include the resulting figure in the document.
?set terminal wxt
?terminal wxt
?set term wxt
?term wxt
?wxt
 The `wxt` terminal device generates output in a separate window. The window
 is created by the wxWidgets library, where the 'wxt' comes from. The actual
 drawing is done via cairo, a 2D graphics library, and pango, a library for
 laying out and rendering text.

 Syntax:
         set term wxt {<n>}
                      {size <width>,<height>} {background <rgb_color>}
                      {{no}enhanced}
                      {font <font>} {fontscale <scale>}
                      {title "title"}
                      {dashed|solid} {dashlength <dl>}
                      {{no}persist}
                      {{no}raise}
                      {{no}ctrl}
                      {close}

 Multiple plot windows are supported: `set terminal wxt <n>` directs the
 output to plot window number n.

 The default window title is based on the window number. This title can also
 be specified with the keyword "title".

 Plot windows remain open even when the `gnuplot` driver is changed to a
 different device.  A plot window can be closed by pressing the letter 'q'
 while that window has input focus, by choosing `close` from a window
 manager menu, or with `set term wxt <n> close`.

 The size of the plot area is given in pixels, it defaults to 640x384.
 In addition to that, the actual size of the window also includes the space
 reserved for the toolbar and the status bar.
 When you resize a window, the plot is immediately scaled to fit in the
 new size of the window. Unlike other interactive terminals, the `wxt`
 terminal scales the whole plot, including fonts and linewidths, and keeps
 its global aspect ratio constant, leaving an empty space painted in gray.
 If you type `replot`, click the `replot` icon in the terminal toolbar or
 type a new `plot` command, the new plot will completely fit in the window
 and the font size and the linewidths will be reset to their defaults.

 The active plot window (the one selected by `set term wxt <n>`) is
 interactive. Its behaviour is shared with other terminal types. See `mouse`
 for details. It also has some extra icons, which are supposed to be
 self-explanatory.

 This terminal supports an enhanced text mode, which allows font and other
 formatting commands (subscripts, superscripts, etc.) to be embedded in labels
 and other text strings. The enhanced text mode syntax is shared with other
 gnuplot terminal types. See `enhanced` for more details.

 <font> is in the format "FontFace,FontSize", i.e. the face and the size
 comma-separated in a single string. FontFace is a usual font face name, such
 as 'Arial'. If you do not provide FontFace, the wxt terminal will use
 'Sans'. FontSize is the font size, in points. If you do not provide it,
 the wxt terminal will use a size of 10 points.
    For example :
       set term wxt font "Arial,12"
       set term wxt font "Arial" # to change the font face only
       set term wxt font ",12" # to change the font size only
       set term wxt font "" # to reset the font name and size

 The fonts are retrieved from the usual fonts subsystems. Under Windows,
 those fonts are to be found and configured in the entry "Fonts" of the
 control panel. Under UNIX, they are handled by "fontconfig".

 Pango, the library used to layout the text, is based on utf-8. Thus, the wxt
 terminal has to convert from your encoding to utf-8. The default input
 encoding is based on your 'locale'. If you want to use another encoding,
 make sure gnuplot knows which one you are using. See `encoding` for more
 details.

 Pango may give unexpected results with fonts that do not respect the unicode
 mapping. With the Symbol font, for example, the wxt terminal will use the map
 provided by http://www.unicode.org/ to translate character codes to unicode.
 Pango will do its best to find a font containing this character, looking for
 your Symbol font, or other fonts with a broad unicode coverage, like the
 DejaVu fonts. Note that "the Symbol font" is to be understood as the Adobe
 Symbol font, distributed with Acrobat Reader as "SY______.PFB".
 Alternatively, the OpenSymbol font, distributed with OpenOffice.org as
 "opens___.ttf", offers the same characters. Microsoft has distributed a
 Symbol font ("symbol.ttf"), but it has a different character set with
 several missing or moved mathematic characters. If you experience problems
 with your default setup (if the demo enhancedtext.dem is not displayed
 properly for example), you probably have to install one of the Adobe or
 OpenOffice Symbol fonts, and remove the Microsoft one.
 Other non-conform fonts, such as "wingdings" have been observed working.

 The rendering of the plot can be altered with a dialog available from the
 toolbar. To obtain the best output possible, the rendering involves three
 mechanisms : antialiasing, oversampling and hinting.
 Antialiasing allows to display non-horizontal and non-vertical lines
 smoother.
 Oversampling combined with antialiasing provides subpixel accuracy,
 so that gnuplot can draw a line from non-integer coordinates. This avoids
 wobbling effects on diagonal lines ('plot x' for example).
 Hinting avoids the blur on horizontal and vertical lines caused by
 oversampling. The terminal will snap these lines to integer coordinates so
 that a one-pixel-wide line will actually be drawn on one and only one pixel.

 By default, the window is raised to the top of your desktop when a plot is
 drawn. This can be controlled with the keyword "raise".
 The keyword "persist" will prevent gnuplot from exiting before you
 explicitely close all the plot windows.
 Finally, by default the key <space> raises the gnuplot console window, and
 'q' closes the plot window. The keyword "ctrl" allows you to replace those
 bindings by <ctrl>+<space> and <ctrl>+'q', respectively.
 These three keywords (raise, persist and ctrl) can also be set and remembered
 between sessions through the configuration dialog.
?set terminal epscairo
?terminal epscairo
?set term epscairo
?term epscairo
?epscairo
 The `epscairo` terminal device generates encapsulated PostScript (*.eps) using
 the cairo and pango support libraries.  cairo verion >= 1.6 is required.

 Please read the help for the `pdfcairo` terminal.
?set terminal cairolatex
?terminal cairolatex
?set term cairolatex
?term cairolatex
?cairolatex
 The `cairolatex` terminal device generates encapsulated PostScript (*.eps) or
 PDF output using the cairo and pango support libraries and uses LaTeX for
 text output using the same routines as the `epslatex` terminal.

 Syntax:
       set terminal cairolatex
                      {eps | pdf}
                      {standalone | input}
                      {blacktext | colortext | colourtext}
                      {header <header> | noheader}
                      {mono|color} {solid|dashed}
                      {{no}transparent} {{no}crop} {background <rgbcolor>}
                      {font <font>} {fontscale <scale>}
                      {linewidth <lw>} {rounded|butt} {dashlength <dl>}
                      {size <XX>{unit},<YY>{unit}}

 The cairolatex terminal prints a plot like `terminal epscairo` or
 `terminal pdfcairo` but transfers the texts to LaTeX instead of including
 them in the graph. For reference of options not explained here see `pdfcairo`.

 `eps` and `pdf` select the type of grahics output. Use `eps` with
 latex/dvips and `pdf` for pdflatex.

 `blacktext` forces all text to be written in black even in color mode;

 The `cairolatex` driver offers a special way of controlling text positioning:
 (a) If any text string begins with '{', you also need to include a '}' at the
 end of the text, and the whole text will be centered both horizontally
 and vertically by LaTeX.  (b) If the text string begins with '[', you need
 to continue it with: a position specification (up to two out of t,b,l,r,c),
 ']{', the text itself, and finally, '}'. The text itself may be anything
 LaTeX can typeset as an LR-box. \rule{}{}'s may help for best positioning.
 See also the documentation for the `pslatex` terminal driver.
 To create multiline labels, use \shortstack, for example
    set ylabel '[r]{\shortstack{first line \\ second line}}'

 The `back` option of `set label` commands is handled slightly different
 than in other terminals. Labels using 'back' are printed behind all other
 elements of the plot while labels using 'front' are printed above
 everything else.

 The driver produces two different files, one for the eps or pdf part of the
 figure and one for the LaTeX part. The name of the LaTeX file is taken from
 the `set output` command. The name of the eps/pdf file is derived by
 replacing the file extension (normally '.tex') with '.eps' or '.pdf' instead.
 There is no LaTeX output if no output file is given!  Remember to close the
 `output file` before next plot unless in `multiplot` mode.

 In your LaTeX documents use '\input{filename}' to include the figure.
 The '.eps' or '.pdf' file is included by the command \includegraphics{...},
 so you must also include \usepackage{graphicx} in the LaTeX preamble.  If
 you want to use coloured text (option `colourtext`) you also have to include
 \usepackage{color} in the LaTeX preamble.

 The behaviour concerning font selection depends on the header mode.
 In all cases, the given font size is used for the calculation of proper
 spacing. When not using the `standalone` mode the actual LaTeX font and
 font size at the point of inclusion is taken, so use LaTeX commands for
 changing fonts. If you use e.g. 12pt as font size for your LaTeX
 document, use '", 12"' as options. The font name is ignored. If using
 `standalone` the given font and font size are used, see below for a
 detailed description.

 If text is printed coloured is controlled by the TeX booleans \ifGPcolor
 and \ifGPblacktext. Only if \ifGPcolor is true and \ifGPblacktext is
 false, text is printed coloured. You may either change them in the
 generated TeX file or provide them globally in your TeX file, for example
 by using
    \newif\ifGPblacktext
    \GPblacktexttrue
 in the preamble of your document. The local assignment is only done if no
 global value is given.

 When using the cairolatex terminal give the name of the TeX file in the
 `set output` command including the file extension (normally ".tex").
 The graph filename is generated by replacing the extension.

 If using the `standalone` mode a complete LaTeX header is added to the
 LaTeX file; and "-inc" is added to the filename of the gaph file.
 The `standalone` mode generates a TeX file that produces
 output with the correct size when using dvips, pdfTeX, or VTeX.
 The default, `input`, generates a file that has to be included into a
 LaTeX document using the \input command.

 If a font other than "" or "default" is given it is interpreted as
 LaTeX font name.  It contains up to three parts, separated by a comma:
 'fontname,fontseries,fontshape'.  If the default fontshape or fontseries
 are requested, they can be omitted.  Thus, the real syntax for the fontname
 is '{fontname}{,fontseries}{,fontshape}'.  The naming convention for all
 parts is given by the LaTeX font scheme.  The fontname is 3 to 4 characters
 long and is built as follows: One character for the font vendor, two
 characters for the name of the font, and optionally one additional
 character for special fonts, e.g., 'j' for fonts with old-style numerals
 or 'x' for expert fonts. The names of many fonts is described in
           http://www.tug.org/fontname/fontname.pdf
 For example, 'cmr' stands for Computer Modern Roman, 'ptm' for Times-Roman,
 and 'phv' for Helvetica.  The font series denotes the thickness of the
 glyphs, in most cases 'm' for normal ("medium") and 'bx' or 'b' for bold
 fonts.  The font shape is 'n' for upright, 'it' for italics, 'sl' for
 slanted, or 'sc' for small caps, in general.  Some fonts may provide
 different font series or shapes.

 Examples:

 Use Times-Roman boldface (with the same shape as in the surrounding text):
       set terminal cairolatex font 'ptm,bx'
 Use Helvetica, boldface, italics:
       set terminal cairolatex font 'phv,bx,it'
 Continue to use the surrounding font in slanted shape:
       set terminal cairolatex font ',,sl'
 Use small capitals:
       set terminal cairolatex font ',,sc'

 By this method, only text fonts are changed. If you also want to change
 the math fonts you have to use the "gnuplot.cfg" file or the `header`
 option, described below.

 In `standalone` mode, the font size is taken from the given font size in the
 `set terminal` command. To be able to use a specified font size, a file
 "size<size>.clo" has to reside in the LaTeX search path.  By default,
 10pt, 11pt, and 12pt are supported.  If the package "extsizes" is
 installed, 8pt, 9pt, 14pt, 17pt, and 20pt are added.

 The `header` option takes a string as argument.  This string is written
 into the generated LaTeX file.  If using the `standalone` mode, it is
 written into the preamble, directly before the \begin{document} command.
 In the `input` mode, it is placed directly after the \begingroup command
 to ensure that all settings are local to the plot.

 Examples:

 Use T1 fontencoding, change the text and math font to Times-Roman as well
 as the sans-serif font to Helvetica:
     set terminal cairolatex standalone header \
     "\\usepackage[T1]{fontenc}\n\\usepackage{mathptmx}\n\\usepackage{helvet}"
 Use a boldface font in the plot, not influencing the text outside the plot:
     set terminal cairolatex input header "\\bfseries"

 If the file "gnuplot.cfg" is found by LaTeX it is input in the preamble
 the LaTeX document, when using `standalone` mode.  It can be used for
 further settings, e.g., changing the document font to Times-Roman,
 Helvetica, and Courier, including math fonts (handled by "mathptmx.sty"):
       \usepackage{mathptmx}
       \usepackage[scaled=0.92]{helvet}
       \usepackage{courier}
 The file "gnuplot.cfg" is loaded before the header information given
 by the `header` command.  Thus, you can use `header` to overwrite some of
 settings performed using "gnuplot.cfg"

?set terminal pdfcairo
?terminal pdfcairo
?set term pdfcairo
?term pdfcairo
?pdfcairo
 The `pdfcairo` terminal device generates output in pdf. The actual
 drawing is done via cairo, a 2D graphics library, and pango, a library for
 laying out and rendering text.

 Syntax:
         set term pdfcairo
                      {{no}enhanced} {mono|color} {solid|dashed}
                      {font <font>} {fontscale <scale>}
                      {linewidth <lw>} {rounded|butt} {dashlength <dl>}
                      {size <XX>{unit},<YY>{unit}}

 This terminal supports an enhanced text mode, which allows font and other
 formatting commands (subscripts, superscripts, etc.) to be embedded in labels
 and other text strings. The enhanced text mode syntax is shared with other
 gnuplot terminal types. See `enhanced` for more details.

 The width of all lines in the plot can be modified by the factor <lw>
 specified in `linewidth`. The default linewidth is 0.25 points.
 (1 "PostScript" point = 1/72 inch = 0.353 mm)

 `rounded` sets line caps and line joins to be rounded; `butt` is the
 default, butt caps and mitered joins.

 The default size for the output is 5 inches x 3 inches. The `size` option
 changes this to whatever the user requests. By default the X and Y sizes are
 taken to be in inches, but other units are possible (currently only cm).
 Screen coordinates always run from 0.0 to 1.0 along the full length of the
 plot edges as specified by the `size` option.

 <font> is in the format "FontFace,FontSize", i.e. the face and the size
 comma-separated in a single string. FontFace is a usual font face name, such
 as 'Arial'. If you do not provide FontFace, the pdfcairo terminal will use
 'Sans'. FontSize is the font size, in points. If you do not provide it,
 the pdfcairo terminal will use a nominal font size of 12 points.
 However, the default fontscale parameter for this terminal is 0.5,
 so the apparent font size is smaller than this if the pdf output is
 viewed at full size.
    For example :
       set term pdfcairo font "Arial,12"
       set term pdfcairo font "Arial" # to change the font face only
       set term pdfcairo font ",12" # to change the font size only
       set term pdfcairo font "" # to reset the font name and size

 The fonts are retrieved from the usual fonts subsystems. Under Windows,
 those fonts are to be found and configured in the entry "Fonts" of the
 control panel. Under UNIX, they are handled by "fontconfig".

 Pango, the library used to layout the text, is based on utf-8. Thus, the pdfcairo
 terminal has to convert from your encoding to utf-8. The default input
 encoding is based on your 'locale'. If you want to use another encoding,
 make sure gnuplot knows which one you are using. See `encoding` for more
 details.

 Pango may give unexpected results with fonts that do not respect the unicode
 mapping. With the Symbol font, for example, the pdfcairo terminal will use the map
 provided by http://www.unicode.org/ to translate character codes to unicode.
 Note that "the Symbol font" is to be understood as the Adobe
 Symbol font, distributed with Acrobat Reader as "SY______.PFB".
 Alternatively, the OpenSymbol font, distributed with OpenOffice.org as
 "opens___.ttf", offers the same characters. Microsoft has distributed a
 Symbol font ("symbol.ttf"), but it has a different character set with
 several missing or moved mathematic characters. If you experience problems
 with your default setup (if the demo enhancedtext.dem is not displayed
 properly for example), you probably have to install one of the Adobe or
 OpenOffice Symbol fonts, and remove the Microsoft one.
 Other non-conform fonts, such as "wingdings" have been observed working.

 The rendering of the plot cannot be altered yet. To obtain the best output
 possible, the rendering involves two mechanisms : antialiasing and
 oversampling.
 Antialiasing allows to display non-horizontal and non-vertical lines
 smoother.
 Oversampling combined with antialiasing provides subpixel accuracy,
 so that gnuplot can draw a line from non-integer coordinates. This avoids
 wobbling effects on diagonal lines ('plot x' for example).

?set terminal pngcairo
?terminal pngcairo
?set term pngcairo
?term pngcairo
?pngcairo
 The `pngcairo` terminal device generates output in png. The actual
 drawing is done via cairo, a 2D graphics library, and pango, a library for
 laying out and rendering text.

 Syntax:
         set term pngcairo
                      {{no}enhanced} {mono|color} {solid|dashed}
                      {{no}transparent} {{no}crop} {background <rgbcolor>
                      {font <font>} {fontscale <scale>}
                      {linewidth <lw>} {rounded|butt} {dashlength <dl>}
                      {size <XX>{unit},<YY>{unit}}

 This terminal supports an enhanced text mode, which allows font and other
 formatting commands (subscripts, superscripts, etc.) to be embedded in labels
 and other text strings. The enhanced text mode syntax is shared with other
 gnuplot terminal types. See `enhanced` for more details.

 The width of all lines in the plot can be modified by the factor <lw>.

 `rounded` sets line caps and line joins to be rounded; `butt` is the
 default, butt caps and mitered joins.

 The default size for the output is 640 x 480 pixels. The `size` option
 changes this to whatever the user requests. By default the X and Y sizes are
 taken to be in pixels, but other units are possible (currently cm and inch).
 A size given in centimeters or inches will be converted into pixels assuming
 a resolution of 72 dpi. Screen coordinates always run from 0.0 to 1.0 along
 the full length of the plot edges as specified by the `size` option.

 <font> is in the format "FontFace,FontSize", i.e. the face and the size
 comma-separated in a single string. FontFace is a usual font face name, such
 as 'Arial'. If you do not provide FontFace, the pngcairo terminal will use
 'Sans'. FontSize is the font size, in points. If you do not provide it,
 the pngcairo terminal will use a size of 12 points.
    For example :
       set term pngcairo font "Arial,12"
       set term pngcairo font "Arial" # to change the font face only
       set term pngcairo font ",12" # to change the font size only
       set term pngcairo font "" # to reset the font name and size

 The fonts are retrieved from the usual fonts subsystems. Under Windows,
 those fonts are to be found and configured in the entry "Fonts" of the
 control panel. Under UNIX, they are handled by "fontconfig".

 Pango, the library used to layout the text, is based on utf-8. Thus, the pngcairo
 terminal has to convert from your encoding to utf-8. The default input
 encoding is based on your 'locale'. If you want to use another encoding,
 make sure gnuplot knows which one you are using. See `encoding` for more
 details.

 Pango may give unexpected results with fonts that do not respect the unicode
 mapping. With the Symbol font, for example, the pngcairo terminal will use the map
 provided by http://www.unicode.org/ to translate character codes to unicode.
 Note that "the Symbol font" is to be understood as the Adobe
 Symbol font, distributed with Acrobat Reader as "SY______.PFB".
 Alternatively, the OpenSymbol font, distributed with OpenOffice.org as
 "opens___.ttf", offers the same characters. Microsoft has distributed a
 Symbol font ("symbol.ttf"), but it has a different character set with
 several missing or moved mathematic characters. If you experience problems
 with your default setup (if the demo enhancedtext.dem is not displayed
 properly for example), you probably have to install one of the Adobe or
 OpenOffice Symbol fonts, and remove the Microsoft one.
 Other non-conform fonts, such as "wingdings" have been observed working.

 The rendering of the plot cannot be altered yet. To obtain the best output
 possible, the rendering involves two mechanisms : antialiasing and
 oversampling.
 Antialiasing allows to display non-horizontal and non-vertical lines
 smoother.
 Oversampling combined with antialiasing provides subpixel accuracy,
 so that gnuplot can draw a line from non-integer coordinates. This avoids
 wobbling effects on diagonal lines ('plot x' for example).

?commands set terminal lua
?set terminal lua
?set term lua
?terminal lua
?term lua
?lua
 The `lua` generic terminal driver works in conjunction with an
 external Lua script to create a target-specific plot file.
 Currently the only supported target is TikZ -> pdflatex.

 Information about Lua is available at http://www.lua.org .

 Syntax:
    set terminal lua <target name> | "<file name>"
                        {<script_args> ...}
                        {help}

 A 'target name' or 'file name' (in quotes) for a script is mandatory.
 If a 'target name' for the script is given, the terminal will look for
 "gnuplot-<target name>.lua" in the local directory and on failure in
 the environmental variable GNUPLOT_LUA_DIR.

 All arguments will be provided to the selected script for further
 evaluation. E.g. 'set term lua tikz help' will cause the script itself
 to print additional help on options and choices for the script.
?set terminal lua tikz
?set term lua tikz
?term lua tikz
 The TikZ driver is one output mode of the generic Lua terminal.

 Syntax:
     set terminal lua tikz

      {latex | tex | context}
      {color | monochrome}
      {dashed | solid}
      {nooriginreset | originreset}
      {nogparrows | gparrows}
      {nogppoints | gppoints}
      {picenvironment | nopicenvironment}
      {noclip | clip}
      {notightboundingbox | tightboundingbox}
      {background "<colorpec>"}
      {size <x>{unit},<y>{unit}}
      {scale <x>,<y>}
      {plotsize <x>{unit},<y>{unit}}
      {charsize <x>{unit},<y>{unit}}
      {font "<fontdesc>"}
      {{fontscale | textscale} <scale>}
      {nofulldoc | nostandalone | fulldoc | standalone}
      {{preamble | header} "<preamble_string>"}
      {tikzplot <ltn>,...}
      {notikzarrows | tikzarrows}
      {rgbimages | cmykimages}
      {noexternalimages|externalimages}
      {bitmap | nobitmap}
      {providevars <var name>,...}
      {createstyle}
      {help}

 For all options that expect lengths as their arguments they
 will default to 'cm' if no unit is specified. For all lengths
 the following units may be used: 'cm', 'mm', 'in' or 'inch',
 'pt', 'pc', 'bp', 'dd', 'cc'. Blanks between numbers and units
 are not allowed.

 'monochrome' disables line coloring and switches to grayscaled
 fills.

 'solid' use only solid lines.

 'originreset' moves the origin of the TikZ picture to the lower
 left corner of the plot. It may be used to align several plots
 within one tikzpicture environment. This is not tested with
 multiplots and pm3d plots!

 'gparrows' use gnuplot's internal arrow drawing function
 instead of the ones provided by TikZ.

 'gppoints' use gnuplot's internal plotmark drawing function
 instead of the ones provided by TikZ.

 'nopicenvironment' omits the declaration of the 'tikzpicture'
 environment in order to set it manually. This permits putting
 some PGF/TikZ code directly before or after the plot.

 'clip' crops the plot at the defined canvas size. Default is
 'noclip' by which only a minimum bounding box of the canvas size
 is set. Neither a fixed bounding box nor a crop box is set if the
 'plotsize' or 'tightboundingbox' option is used.

 If 'tightboundingbox' is set the 'clip' option is ignored and the
 final bounding box is the natural bounding box calculated by tikz.

 'background' sets the background color to the value specified in
 the <colorpec> argument. <colorspec> must be a valid color name or
 a 3 byte RGB code as a hexadecimal number with a preceding number
 sign ('#'). E.g. '#ff0000' specifies pure red. If omitted the
 background is transparent.

 The 'size' option expects two lenghts <x> and <y> as the canvas
 size. The default size of the canvas is 12.5cm x 8.75cm.

 The 'scale' option works similar to the 'size' option but expects
 scaling factors <x> and <y> instead of lengths.

 The 'plotsize' option permits setting the size of the plot area
 instead of the canvas size, which is the usual gnuplot behaviour.
 Using this option may lead to slightly asymmetric tic lengths.
 Like 'originreset' this option may not lead to convenient results
 if used with multiplots or pm3d plots. An alternative approach
 is to set all margins to zero and to use the 'noclip' option.
 The plot area has then the dimensions of the given canvas sizes.

 The 'charsize' option expects the average horizontal and vertical
 size of the used font. Look at the generated style file for an
 example of how to use it from within your TeX document.

 'fontscale' or 'textscale' expects a scaling factor as a parameter.
 All texts in the plot are scaled by this factor then.

 The options 'tex', 'latex' and 'context' choose the TeX output
 format. LaTeX is the default. To load the style file put the
 according line at the beginning of your document:
   \input gnuplot-lua-tikz.tex    % (for plain TeX)
   \usepackage{gnuplot-lua-tikz}  % (for LaTeX)
   \usemodule[gnuplot-lua-tikz]   % (for ConTeXt)

 'createstyle' derives the TeX/LaTeX/ConTeXt styles from the script
 and writes them to the appropriate files.

 'fulldoc' or 'standalone' produces a full LaTeX document for direct
 compilation.

 'preamble' or 'header' may be used to put any additional LaTeX code
 into the document preamble in standalone mode.

 With the 'tikzplot' option the '\path plot' command will be used
 instead of only '\path'. The following list of numbers of linetypes
 (<ltn>,...) defines the affected plotlines. There exists a plotstyle
 for every linetype. The default plotstyle is 'smooth' for every
 linetype >= 1.

 By using the 'tikzarrows' option the gnuplot arrow styles defined by
 the user will be mapped to TikZ arrow styles. This is done by 'misusing'
 the angle value of the arrow definition. E.g. an arrow style with the
 angle '7' will be mapped to the TikZ style 'gp arrow 7' ignoring all the
 other given values. By default the TikZ terminal uses the stealth' arrow
 tips for all arrows. To obtain the default gnuplot behaviour please use
 the 'gparrows' option.

 With 'cmykimages' the CMYK color model will be used for inline image data
 instead of the RGB model. All other colors (like line colors etc.) are
 not affected by this option, since they are handled e.g. by LaTeX's
 xcolor package. This option is ignored if images are externalized.

 By using the 'externalimages' option all bitmap images will be written
 as external PNG images and included at compile time of the document.
 Generating DVI and later postscript files requires to convert the PNGs
 into EPS files in a seperate step e.g. by using ImageMagick's `convert`.
 Transparent bitmap images are always generated as an external PNGs.

 The 'nobitmap' option let images be rendered as filled rectangles instead
 of the nativ PS or PDF inline image format. This option is ignored if
 images are externalized.

 The 'providevars' options makes gnuplot's internal and user variables
 available by using the '\gpgetvar{<var name>}' commmand within the TeX
 script. Use gnuplot's 'show variables all' command to see the list
 of valid variables.

 The <fontdesc> string may contain any valid TeX/LaTeX/ConTeXt font commands
 like e.g. '\small'. It is passed directly as a node parameter in form of
 "font={<fontdesc>}". This can be 'misused' to add further code to a node,
 e.g. '\small,yshift=1ex' or ',yshift=1ex' are also valid while the
 latter does not change the current font settings. One exception is
 the second argument of the list. If it is a number of the form
 <number>{unit} it will be interpreted as a fontsize like in other
 terminals and will be appended to the first argument. If the unit is
 omitted the value is interpreted as 'pt'. As an example the string
 '\sffamily,12,fill=red' sets the font to LaTeX's sans serif font at
 a size of 12pt and red background color.
 The same applies to ConTeXt, e.g. '\switchtobodyfont[iwona],10' changes the
 font to Iwona at a size of 10pt.
 Plain TeX users have to change the font size explicitly within the first
 argument. The second should be set to the same value to get proper scaling
 of text boxes.

 Strings have to be put in single or double quotes. Double quoted
 strings may contain special characters like newlines '\n' etc.

?commands set terminal tikz
?set terminal tikz
?set term tikz
?terminal tikz
?term tikz
?tikz
 This driver creates output for use with the TikZ package of graphics macros
 in TeX.  It is currently implemented via an external lua script, and 
 `set term tikz` is a short form of the command `set term lua tikz`.
 See `term lua` for more information.  Use the command `set term tikz help`
 to print terminal options.
?set terminal qt
?terminal qt
?set term qt
?term qt
?qt
 The `qt` terminal device generates output in a separate window with the Qt library.
 Syntax:
         set term qt {<n>}
                     {size <width>,<height>}
                     {{no}enhanced}
                     {font <font>}
                     {title "title"}
                     {{no}persist}
                     {{no}raise}
                     {{no}ctrl}
                     {close}
                     {widget <id>}

 Multiple plot windows are supported: `set terminal qt <n>` directs the
 output to plot window number n.

 The default window title is based on the window number. This title can also
 be specified with the keyword "title".

 Plot windows remain open even when the `gnuplot` driver is changed to a
 different device. A plot window can be closed by pressing the letter 'q'
 while that window has input focus, by choosing `close` from a window
 manager menu, or with `set term qt <n> close`.

 The size of the plot area is given in pixels, it defaults to 640x480.
 In addition to that, the actual size of the window also includes the space
 reserved for the toolbar and the status bar.
 When you resize a window, the plot is immediately scaled to fit in the
 new size of the window. The `qt` terminal scales the whole plot, including
 fonts and linewidths, and keeps its global aspect ratio constant.
 If you type `replot`, click the `replot` icon in the terminal toolbar or
 type a new `plot` command, the new plot will completely fit in the window
 and the font size and the linewidths will be reset to their defaults.

 The active plot window (the one selected by `set term qt <n>`) is
 interactive. Its behaviour is shared with other terminal types. See `mouse`
 for details. It also has some extra icons, which are supposed to be
 self-explanatory.

 This terminal supports an enhanced text mode, which allows font and other
 formatting commands (subscripts, superscripts, etc.) to be embedded in labels
 and other text strings. The enhanced text mode syntax is shared with other
 gnuplot terminal types. See `enhanced` for more details.

 <font> is in the format "FontFace,FontSize", i.e. the face and the size
 comma-separated in a single string. FontFace is a usual font face name, such
 as 'Arial'. If you do not provide FontFace, the qt terminal will use
 'Sans'. FontSize is the font size, in points. If you do not provide it,
 the qt terminal will use a size of 9 points.
    For example :
       set term qt font "Arial,12"
       set term qt font "Arial" # to change the font face only
       set term qt font ",12" # to change the font size only
       set term qt font "" # to reset the font name and size

 The Qt rendering speed is affected strongly by the rendering mode used.
 In Qt version 4.7 or newer this can be controlled by the environmental
 variable QT_GRAPHICSSYSTEM. The options are "native", "raster", or
 "opengl" in order of increasing rendering speed.  For earlier versions
 of Qt the terminal defaults to "raster".

 To obtain the best output possible, the rendering involves three
 mechanisms : antialiasing, oversampling and hinting.
 Oversampling combined with antialiasing provides subpixel accuracy,
 so that gnuplot can draw a line from non-integer coordinates. This avoids
 wobbling effects on diagonal lines ('plot x' for example).
 Hinting avoids the blur on horizontal and vertical lines caused by
 oversampling. The terminal will snap these lines to integer coordinates so
 that a one-pixel-wide line will actually be drawn on one and only one pixel.

 By default, the window is raised to the top of your desktop when a plot is
 drawn. This can be controlled with the keyword "raise".
 The keyword "persist" will prevent gnuplot from exiting before you
 explicitely close all the plot windows.
 Finally, by default the key <space> raises the gnuplot console window, and
 'q' closes the plot window. The keyword "ctrl" allows you to replace those
 bindings by <ctrl>+<space> and <ctrl>+'q', respectively.

 The gnuplot outboard driver, gnuplot_qt, is searched in a default place
 chosen when the program is compiled.  You can override that by defining
 the environment variable GNUPLOT_DRIVER_DIR to point to a different
 location.
?bugs
 Please e-mail bug reports to the gnuplot-bugs mailing list or
 upload the report to the gnuplot web site on SourceForge.
 Please give complete information on the version of gnuplot you are using
 and, if possible, a test script that demonstrates the bug.
 See `seeking-assistance`.

 It is not possible to use in-line data (e.g. plot '-' ...) inside the curly
 brackets of a `do` or `while` loop.

 The layout and positioning of the plot key is inaccurate whenever superscripts,
 subscripts, or explicit fonts are used in the key text.  (Fixed in 4.7)

 Floating point exceptions (floating point number too large/small, divide by
 zero, etc.) may occasionally be generated by user defined functions.  Some of
 the demos in particular may cause numbers to exceed the floating point range.
 Whether the system ignores such exceptions (in which case `gnuplot` labels
 the corresponding point as undefined) or aborts `gnuplot` depends on the
 compiler/runtime environment.

 The gamma, bessel, and erf functions do not work for complex arguments.

 Coordinates specified as "time" wrap at 24 hours.

 The 'nohidden3d' option that is supposed to exempt individual plots from the
 global property 'set hidden3d' does not work for parametric curves.

 X11 terminal: It is difficult to select UTF-8 fonts.  The program does not
 track the true aspect ratio of the x11 terminal window.  In order for commands
 such as "set size ratio" to work, the x11 window must itself have equal height
 and width.  Only one color palette at a time is active for any given x11 plot
 window.  This means that multiplots whose constituent plots use different
 palettes will not display correctly in x11.

 Qt terminal: If the local qt environment does not support "opengl" as a
 rendering mode then display of polygons and surfaces can be very slow.

?bugs external_libraries
 External library GD (used by PNG/JPEG/GIF drivers):
 Versions of libgd through 2.0.33 contain various bugs in mapping the characters
 of Adobe's Symbol font.  Also it is possible to trigger a library segfault if
 an anti-aliased line crosses an upper corner of the canvas.

 External library PDFlib (used by PDF driver):
 Gnuplot can be linked against libpdf versions 4, 5, or 6. However, these
 versions differ in their handling of piped I/O.  Therefore gnuplot scripts
 using piped output to PDF may work only for some versions of PDFlib.

 External library svgalib (used by linux and vgagl driver):
 Requires gnuplot to be suid root (bad!) and has many bugs that are specific
 to the video card or graphics driver used in X11.

 Internationalization (locale settings):
 Gnuplot uses the C runtime library routine setlocale() to control
 locale-specific formatting of input and output number, times, and date strings.
 The locales available, and the level of support for locale features such as
 "thousands' grouping separator", depend on the internationalization support
 provided by your individual machine.