This file is indexed.

/usr/include/root/Math/Dfact.h is in libroot-math-smatrix-dev 5.34.30-0ubuntu8.

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
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
// @(#)root/smatrix:$Id$
// Authors: T. Glebe, L. Moneta    2005  

#ifndef ROOT_Math_Dfact
#define ROOT_Math_Dfact
// ********************************************************************
//
// source:
//
// type:      source code
//
// created:   02. Apr 2001
//
// author:    Thorsten Glebe
//            HERA-B Collaboration
//            Max-Planck-Institut fuer Kernphysik
//            Saupfercheckweg 1
//            69117 Heidelberg
//            Germany
//            E-mail: T.Glebe@mpi-hd.mpg.de
//
// Description: Determinant of a square matrix
//              Code was taken from CERNLIB::kernlib dfact function, translated
//              from FORTRAN to C++ and optimized.
//
// changes:
// 02 Apr 2001 (TG) creation
//
// ********************************************************************

#include <cmath>

#ifndef ROOT_Math_MatrixRepresentationsStatic
#include "Math/MatrixRepresentationsStatic.h"
#endif

namespace ROOT { 

  namespace Math { 



/** 
    Detrminant for a general squared matrix
    Function to compute the determinant from a square matrix (\f$ \det(A)\f$) of
    dimension idim and order n.

    @author T. Glebe
*/
template <unsigned int n, unsigned int idim = n>
class Determinant { 
public:
 
template <class T> 
static bool Dfact(MatRepStd<T,n,idim>& rhs, T& det) {

#ifdef XXX
  if (idim < n || n <= 0) {
    return false;
  }
#endif


  /* Initialized data */
  //  const typename MatrixRep::value_type* A = rhs.Array();
  //typename MatrixRep::value_type* a = rhs.Array();

  /* Local variables */
  unsigned int nxch, i, j, k, l;
  //static typename MatrixRep::value_type p, q, tf;
  T p, q, tf;
  
  /* Parameter adjustments */
  //  a -= idim + 1;
  const int arrayOffset = - int(idim+1);
  /* Function Body */
  
  // fact.inc
  
   nxch = 0;
   det = 1.;
   for (j = 1; j <= n; ++j) {
      const unsigned int ji = j * idim;
      const unsigned int jj = j + ji;

      k = j;
      p = std::abs(rhs[jj + arrayOffset]);

      if (j != n) {
         for (i = j + 1; i <= n; ++i) {
            q = std::abs(rhs[i + ji + arrayOffset]);
            if (q > p) {
               k = i;
               p = q;
            }
         } // for i
         if (k != j) {
            for (l = 1; l <= n; ++l) {
               const unsigned int li = l*idim;
               const unsigned int jli = j + li;
               const unsigned int kli = k + li;
               tf = rhs[jli + arrayOffset];
               rhs[jli + arrayOffset] = rhs[kli + arrayOffset];
               rhs[kli + arrayOffset] = tf;
            } // for l
            ++nxch;
         } // if k != j
      } // if j!=n

      if (p <= 0.) {
         det = 0;
         return false;
      }

      det *= rhs[jj + arrayOffset];
#ifdef XXX
      t = std::abs(det);
      if (t < 1e-19 || t > 1e19) {
         det = 0;
         return false;
      }
#endif
      // using 1.0f removes a warning on Windows (1.0f is still the same  as 1.0)
      rhs[jj + arrayOffset] = 1.0f / rhs[jj + arrayOffset];
      if (j == n) {
         continue;
      }

      const unsigned int jm1 = j - 1;
      const unsigned int jpi = (j + 1) * idim;
      const unsigned int jjpi = j + jpi;

      for (k = j + 1; k <= n; ++k) {
         const unsigned int ki  = k * idim;
         const unsigned int jki = j + ki;
         const unsigned int kji = k + jpi;
         if (j != 1) {
            for (i = 1; i <= jm1; ++i) {
               const unsigned int ii = i * idim;
               rhs[jki + arrayOffset] -= rhs[i + ki + arrayOffset] * rhs[j + ii + arrayOffset];
               rhs[kji + arrayOffset] -= rhs[i + jpi + arrayOffset] * rhs[k + ii + arrayOffset];
            } // for i
         }
         rhs[jki + arrayOffset] *= rhs[jj + arrayOffset];
         rhs[kji + arrayOffset] -= rhs[jjpi + arrayOffset] * rhs[k + ji + arrayOffset];
      } // for k
   } // for j
   
   if (nxch % 2 != 0) {
      det = -(det);
  }
  return true;
} // end of Dfact


   // t.b.d re-implement methods for symmetric
  // symmetric function (copy in a general  one) 
  template <class T>
  static bool Dfact(MatRepSym<T,n> & rhs, T & det) {
    // not very efficient but need to re-do Dsinv for new storage of 
    // symmetric matrices
    MatRepStd<T,n> tmp; 
    for (unsigned int i = 0; i< n*n; ++i) 
      tmp[i] = rhs[i];
    if (! Determinant<n>::Dfact(tmp,det) ) return false;
//     // recopy the data
//     for (int i = 0; i< idim*n; ++i) 
//       rhs[i] = tmp[i];

    return true; 
  }

};


  }  // namespace Math

}  // namespace ROOT
          


#endif /* ROOT_Math_Dfact */