src/gromacs/math/invertmatrix.cpp

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  35 /*! \internal \file
  36  * \brief
  37  * Routines to invert 3x3 matrices
  38  *
  39  * \author Mark Abraham <mark.j.abraham@gmail.com>
  40  * \ingroup module_math
  41  */
  42 #include "gmxpre.h"
  43
  44 #include "invertmatrix.h"
  45
  46 #include <cmath>
  47
  48 #include "gromacs/utility/fatalerror.h"
  49 #include "gromacs/utility/gmxassert.h"
  50
  51 namespace gmx
  52 {
  53
  54 void invertBoxMatrix(const matrix src, matrix dest)
  55 {
  56     double tmp = src[XX][XX] * src[YY][YY] * src[ZZ][ZZ];
  57     if (std::fabs(tmp) <= 100 * GMX_REAL_MIN)
  58     {
  59         gmx_fatal(FARGS, "Can not invert matrix, determinant is zero");
  60     }
  61
  62     dest[XX][XX] = 1 / src[XX][XX];
  63     dest[YY][YY] = 1 / src[YY][YY];
  64     dest[ZZ][ZZ] = 1 / src[ZZ][ZZ];
  65     dest[ZZ][XX] = (src[YY][XX] * src[ZZ][YY] * dest[YY][YY] - src[ZZ][XX]) * dest[XX][XX] * dest[ZZ][ZZ];
  66     dest[YY][XX] = -src[YY][XX] * dest[XX][XX] * dest[YY][YY];
  67     dest[ZZ][YY] = -src[ZZ][YY] * dest[YY][YY] * dest[ZZ][ZZ];
  68     dest[XX][YY] = 0.0;
  69     dest[XX][ZZ] = 0.0;
  70     dest[YY][ZZ] = 0.0;
  71 }
  72
  73 void invertMatrix(const matrix src, matrix dest)
  74 {
  75     const real smallreal = 1.0e-24_real;
  76     const real largereal = 1.0e24_real;
  77
  78     real determinant = det(src);
  79     real c           = 1.0_real / determinant;
  80     real fc          = std::fabs(c);
  81
  82     if ((fc <= smallreal) || (fc >= largereal))
  83     {
  84         gmx_fatal(FARGS, "Can not invert matrix, determinant = %e", determinant);
  85     }
  86     GMX_ASSERT(dest != src, "Cannot do in-place inversion of matrix");
  87
  88     dest[XX][XX] = c * (src[YY][YY] * src[ZZ][ZZ] - src[ZZ][YY] * src[YY][ZZ]);
  89     dest[XX][YY] = -c * (src[XX][YY] * src[ZZ][ZZ] - src[ZZ][YY] * src[XX][ZZ]);
  90     dest[XX][ZZ] = c * (src[XX][YY] * src[YY][ZZ] - src[YY][YY] * src[XX][ZZ]);
  91     dest[YY][XX] = -c * (src[YY][XX] * src[ZZ][ZZ] - src[ZZ][XX] * src[YY][ZZ]);
  92     dest[YY][YY] = c * (src[XX][XX] * src[ZZ][ZZ] - src[ZZ][XX] * src[XX][ZZ]);
  93     dest[YY][ZZ] = -c * (src[XX][XX] * src[YY][ZZ] - src[YY][XX] * src[XX][ZZ]);
  94     dest[ZZ][XX] = c * (src[YY][XX] * src[ZZ][YY] - src[ZZ][XX] * src[YY][YY]);
  95     dest[ZZ][YY] = -c * (src[XX][XX] * src[ZZ][YY] - src[ZZ][XX] * src[XX][YY]);
  96     dest[ZZ][ZZ] = c * (src[XX][XX] * src[YY][YY] - src[YY][XX] * src[XX][YY]);
  97 }
  98
  99 } // namespace gmx