/usr/share/postgresql/10/extension/earthdistance--1.1.sql is in postgresql-10 10.6-0ubuntu0.18.04.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 | /* contrib/earthdistance/earthdistance--1.1.sql */
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
\echo Use "CREATE EXTENSION earthdistance" to load this file. \quit
-- earth() returns the radius of the earth in meters. This is the only
-- place you need to change things for the cube base distance functions
-- in order to use different units (or a better value for the Earth's radius).
CREATE FUNCTION earth() RETURNS float8
LANGUAGE SQL IMMUTABLE PARALLEL SAFE
AS 'SELECT ''6378168''::float8';
-- Astronomers may want to change the earth function so that distances will be
-- returned in degrees. To do this comment out the above definition and
-- uncomment the one below. Note that doing this will break the regression
-- tests.
--
-- CREATE FUNCTION earth() RETURNS float8
-- LANGUAGE SQL IMMUTABLE
-- AS 'SELECT 180/pi()';
-- Define domain for locations on the surface of the earth using a cube
-- datatype with constraints. cube provides 3D indexing.
-- The cube is restricted to be a point, no more than 3 dimensions
-- (for less than 3 dimensions 0 is assumed for the missing coordinates)
-- and that the point must be very near the surface of the sphere
-- centered about the origin with the radius of the earth.
CREATE DOMAIN earth AS cube
CONSTRAINT not_point check(cube_is_point(value))
CONSTRAINT not_3d check(cube_dim(value) <= 3)
CONSTRAINT on_surface check(abs(cube_distance(value, '(0)'::cube) /
earth() - 1) < '10e-7'::float8);
CREATE FUNCTION sec_to_gc(float8)
RETURNS float8
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT CASE WHEN $1 < 0 THEN 0::float8 WHEN $1/(2*earth()) > 1 THEN pi()*earth() ELSE 2*earth()*asin($1/(2*earth())) END';
CREATE FUNCTION gc_to_sec(float8)
RETURNS float8
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT CASE WHEN $1 < 0 THEN 0::float8 WHEN $1/earth() > pi() THEN 2*earth() ELSE 2*earth()*sin($1/(2*earth())) END';
CREATE FUNCTION ll_to_earth(float8, float8)
RETURNS earth
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT cube(cube(cube(earth()*cos(radians($1))*cos(radians($2))),earth()*cos(radians($1))*sin(radians($2))),earth()*sin(radians($1)))::earth';
CREATE FUNCTION latitude(earth)
RETURNS float8
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT CASE WHEN cube_ll_coord($1, 3)/earth() < -1 THEN -90::float8 WHEN cube_ll_coord($1, 3)/earth() > 1 THEN 90::float8 ELSE degrees(asin(cube_ll_coord($1, 3)/earth())) END';
CREATE FUNCTION longitude(earth)
RETURNS float8
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT degrees(atan2(cube_ll_coord($1, 2), cube_ll_coord($1, 1)))';
CREATE FUNCTION earth_distance(earth, earth)
RETURNS float8
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT sec_to_gc(cube_distance($1, $2))';
CREATE FUNCTION earth_box(earth, float8)
RETURNS cube
LANGUAGE SQL
IMMUTABLE STRICT
PARALLEL SAFE
AS 'SELECT cube_enlarge($1, gc_to_sec($2), 3)';
--------------- geo_distance
CREATE FUNCTION geo_distance (point, point)
RETURNS float8
LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE AS 'MODULE_PATHNAME';
--------------- geo_distance as operator <@>
CREATE OPERATOR <@> (
LEFTARG = point,
RIGHTARG = point,
PROCEDURE = geo_distance,
COMMUTATOR = <@>
);
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