libstdc++-v3/include/tr1/special_function_util.h

   1 // Special functions -*- C++ -*-
   2
   3 // Copyright (C) 2006-2023 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file tr1/special_function_util.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{tr1/cmath}
  28  */
  29
  30 //
  31 // ISO C++ 14882 TR1: 5.2  Special functions
  32 //
  33
  34 // Written by Edward Smith-Rowland based on numerous mathematics books.
  35
  36 #ifndef _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H
  37 #define _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H 1
  38
  39 namespace std _GLIBCXX_VISIBILITY(default)
  40 {
  41 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  42
  43 #if _GLIBCXX_USE_STD_SPEC_FUNCS
  44 #elif defined(_GLIBCXX_TR1_CMATH)
  45 namespace tr1
  46 {
  47 #else
  48 # error do not include this header directly, use <cmath> or <tr1/cmath>
  49 #endif
  50   namespace __detail
  51   {
  52     /// A class to encapsulate type dependent floating point
  53     /// constants.  Not everything will be able to be expressed as
  54     /// type logic.
  55     template<typename _Tp>
  56     struct __floating_point_constant
  57     {
  58       static const _Tp __value;
  59     };
  60
  61
  62     /// A structure for numeric constants.
  63     template<typename _Tp>
  64       struct __numeric_constants
  65       {
  66         ///  Constant @f$ \pi @f$.
  67         static _Tp __pi() throw()
  68         { return static_cast<_Tp>(3.1415926535897932384626433832795029L); }
  69         ///  Constant @f$ \pi / 2 @f$.
  70         static _Tp __pi_2() throw()
  71         { return static_cast<_Tp>(1.5707963267948966192313216916397514L); }
  72         ///  Constant @f$ \pi / 3 @f$.
  73         static _Tp __pi_3() throw()
  74         { return static_cast<_Tp>(1.0471975511965977461542144610931676L); }
  75         ///  Constant @f$ \pi / 4 @f$.
  76         static _Tp __pi_4() throw()
  77         { return static_cast<_Tp>(0.7853981633974483096156608458198757L); }
  78         ///  Constant @f$ 1 / \pi @f$.
  79         static _Tp __1_pi() throw()
  80         { return static_cast<_Tp>(0.3183098861837906715377675267450287L); }
  81         ///  Constant @f$ 2 / \sqrt(\pi) @f$.
  82         static _Tp __2_sqrtpi() throw()
  83         { return static_cast<_Tp>(1.1283791670955125738961589031215452L); }
  84         ///  Constant @f$ \sqrt(2) @f$.
  85         static _Tp __sqrt2() throw()
  86         { return static_cast<_Tp>(1.4142135623730950488016887242096981L); }
  87         ///  Constant @f$ \sqrt(3) @f$.
  88         static _Tp __sqrt3() throw()
  89         { return static_cast<_Tp>(1.7320508075688772935274463415058723L); }
  90         ///  Constant @f$ \sqrt(\pi/2) @f$.
  91         static _Tp __sqrtpio2() throw()
  92         { return static_cast<_Tp>(1.2533141373155002512078826424055226L); }
  93         ///  Constant @f$ 1 / sqrt(2) @f$.
  94         static _Tp __sqrt1_2() throw()
  95         { return static_cast<_Tp>(0.7071067811865475244008443621048490L); }
  96         ///  Constant @f$ \log(\pi) @f$.
  97         static _Tp __lnpi() throw()
  98         { return static_cast<_Tp>(1.1447298858494001741434273513530587L); }
  99         ///  Constant Euler's constant @f$ \gamma_E @f$.
 100         static _Tp __gamma_e() throw()
 101         { return static_cast<_Tp>(0.5772156649015328606065120900824024L); }
 102         ///  Constant Euler-Mascheroni @f$ e @f$
 103         static _Tp __euler() throw()
 104         { return static_cast<_Tp>(2.7182818284590452353602874713526625L); }
 105       };
 106
 107
 108 #if _GLIBCXX_USE_C99_MATH && !_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC
 109
 110     /// This is a wrapper for the isnan function. Otherwise, for NaN,
 111     /// all comparisons result in false. If/when we build a std::isnan
 112     /// out of intrinsics, this will disappear completely in favor of
 113     /// std::isnan.
 114     template<typename _Tp>
 115     inline bool __isnan(_Tp __x)
 116     { return std::isnan(__x); }
 117
 118 #else
 119
 120     template<typename _Tp>
 121     inline bool __isnan(const _Tp __x)
 122     { return __builtin_isnan(__x); }
 123
 124     template<>
 125     inline bool __isnan<float>(float __x)
 126     { return __builtin_isnanf(__x); }
 127
 128     template<>
 129     inline bool __isnan<long double>(long double __x)
 130     { return __builtin_isnanl(__x); }
 131
 132 #endif
 133   } // namespace __detail
 134 #if ! _GLIBCXX_USE_STD_SPEC_FUNCS && defined(_GLIBCXX_TR1_CMATH)
 135 } // namespace tr1
 136 #endif
 137
 138 _GLIBCXX_END_NAMESPACE_VERSION
 139 }
 140
 141 #endif // _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H
 142