src/gromacs/utility/real.h

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  37 /*! \file
  38  * \brief
  39  * Declares `real` and related constants.
  40  *
  41  * \inpublicapi
  42  * \ingroup module_utility
  43  */
  44 #ifndef GMX_UTILITY_REAL_H
  45 #define GMX_UTILITY_REAL_H
  46
  47 /*! \brief Double precision accuracy */
  48 #define GMX_DOUBLE_EPS   2.2204460492503131e-16
  49
  50 /*! \brief Maximum double precision value - reduced 1 unit in last digit for MSVC */
  51 #define GMX_DOUBLE_MAX   1.7976931348623157e+308
  52
  53 /*! \brief Minimum double precision value */
  54 #define GMX_DOUBLE_MIN   2.2250738585072014e-308
  55
  56 /*! \brief Single precision accuracy */
  57 #define GMX_FLOAT_EPS    1.19209290e-07F
  58
  59 /*! \brief Maximum single precision value - reduced 1 unit in last digit for MSVC */
  60 #define GMX_FLOAT_MAX    3.40282346E+38F
  61
  62 /*! \brief Minimum single precision value */
  63 #define GMX_FLOAT_MIN    1.175494351E-38F
  64
  65 #ifdef __PGI
  66 /* The portland group x86 C/C++ compilers do not treat negative zero initializers
  67  * correctly, but "optimizes" them to positive zero, so we implement it explicitly.
  68  * These constructs are optimized to simple loads at compile time. If you want to
  69  * use them on other compilers those have to support gcc preprocessor extensions.
  70  * Note: These initializers might be sensitive to the endianness (which can
  71  * be different for byte and word order), so check that it works for your platform
  72  * and add a separate section if necessary before adding to the ifdef above.
  73  */
  74 #    define GMX_DOUBLE_NEGZERO  ({ const union { int  di[2]; double d; } _gmx_dzero = {0, -2147483648}; _gmx_dzero.d; })
  75 #    define GMX_FLOAT_NEGZERO   ({ const union { int  fi; float f; } _gmx_fzero = {-2147483648}; _gmx_fzero.f; })
  76 #else
  77 /*! \brief Negative zero in double */
  78 #    define GMX_DOUBLE_NEGZERO  (-0.0)
  79
  80 /*! \brief Negative zero in float */
  81 #    define GMX_FLOAT_NEGZERO   (-0.0f)
  82 #endif
  83
  84 /*! \typedef real
  85  * \brief Precision-dependent \Gromacs floating-point type.
  86  */
  87 /*! \def HAVE_REAL
  88  * \brief Used to check whether `real` is already defined.
  89  */
  90 /*! \def GMX_MPI_REAL
  91  * \brief MPI data type for `real`.
  92  */
  93 /*! \def GMX_REAL_EPS
  94  * \brief Accuracy for `real`.
  95  */
  96 /*! \def GMX_REAL_MIN
  97  * \brief Smallest non-zero value for `real`.
  98  */
  99 /*! \def GMX_REAL_MAX
 100  * \brief Largest finite value for `real`.
 101  */
 102 /*! \def GMX_REAL_NEGZERO
 103  * \brief Negative zero for `real`.
 104  */
 105 /*! \def gmx_real_fullprecision_pfmt
 106  * \brief Format string for full `real` precision.
 107  */
 108 #if GMX_DOUBLE
 109
 110 #ifndef HAVE_REAL
 111 typedef double      real;
 112 #define HAVE_REAL
 113 #endif
 114
 115 #define GMX_MPI_REAL      MPI_DOUBLE
 116 #define GMX_REAL_EPS      GMX_DOUBLE_EPS
 117 #define GMX_REAL_MIN      GMX_DOUBLE_MIN
 118 #define GMX_REAL_MAX      GMX_DOUBLE_MAX
 119 #define GMX_REAL_NEGZERO  GMX_DOUBLE_NEGZERO
 120 #define gmx_real_fullprecision_pfmt "%21.14e"
 121
 122 #else /* GMX_DOUBLE */
 123
 124 #ifndef HAVE_REAL
 125 typedef float           real;
 126 #define HAVE_REAL
 127 #endif
 128
 129 #define GMX_MPI_REAL      MPI_FLOAT
 130 #define GMX_REAL_EPS      GMX_FLOAT_EPS
 131 #define GMX_REAL_MIN      GMX_FLOAT_MIN
 132 #define GMX_REAL_MAX      GMX_FLOAT_MAX
 133 #define GMX_REAL_NEGZERO  GMX_FLOAT_NEGZERO
 134 #define gmx_real_fullprecision_pfmt "%14.7e"
 135
 136 #endif /* GMX_DOUBLE */
 137
 138 #endif