src/gromacs/math/invertmatrix.cpp

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
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   4  * Copyright (c) 2015, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
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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]
  66                     - src[ZZ][XX])*dest[XX][XX]*dest[ZZ][ZZ];
  67     dest[YY][XX] = -src[YY][XX]*dest[XX][XX]*dest[YY][YY];
  68     dest[ZZ][YY] = -src[ZZ][YY]*dest[YY][YY]*dest[ZZ][ZZ];
  69     dest[XX][YY] = 0.0;
  70     dest[XX][ZZ] = 0.0;
  71     dest[YY][ZZ] = 0.0;
  72 }
  73
  74 void invertMatrix(const matrix src, matrix dest)
  75 {
  76     const real smallreal = (real)1.0e-24;
  77     const real largereal = (real)1.0e24;
  78
  79     real       determinant = det(src);
  80     real       c           = (real)1.0/determinant;
  81     real       fc          = (real)std::fabs(c);
  82
  83     if ((fc <= smallreal) || (fc >= largereal))
  84     {
  85         gmx_fatal(FARGS, "Can not invert matrix, determinant = %e", determinant);
  86     }
  87     GMX_ASSERT(dest != src, "Cannot do in-place inversion of matrix");
  88
  89     dest[XX][XX] = c*(src[YY][YY]*src[ZZ][ZZ]-src[ZZ][YY]*src[YY][ZZ]);
  90     dest[XX][YY] = -c*(src[XX][YY]*src[ZZ][ZZ]-src[ZZ][YY]*src[XX][ZZ]);
  91     dest[XX][ZZ] = c*(src[XX][YY]*src[YY][ZZ]-src[YY][YY]*src[XX][ZZ]);
  92     dest[YY][XX] = -c*(src[YY][XX]*src[ZZ][ZZ]-src[ZZ][XX]*src[YY][ZZ]);
  93     dest[YY][YY] = c*(src[XX][XX]*src[ZZ][ZZ]-src[ZZ][XX]*src[XX][ZZ]);
  94     dest[YY][ZZ] = -c*(src[XX][XX]*src[YY][ZZ]-src[YY][XX]*src[XX][ZZ]);
  95     dest[ZZ][XX] = c*(src[YY][XX]*src[ZZ][YY]-src[ZZ][XX]*src[YY][YY]);
  96     dest[ZZ][YY] = -c*(src[XX][XX]*src[ZZ][YY]-src[ZZ][XX]*src[XX][YY]);
  97     dest[ZZ][ZZ] = c*(src[XX][XX]*src[YY][YY]-src[YY][XX]*src[XX][YY]);
  98 }
  99
 100 } // namespace