libstdc++
special_function_util.h
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1 // Special functions -*- C++ -*-
2 
3 // Copyright (C) 2006, 2009
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16 
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
25 
26 /** @file tr1/special_function_util.h
27  * This is an internal header file, included by other library headers.
28  * You should not attempt to use it directly.
29  */
30 
31 //
32 // ISO C++ 14882 TR1: 5.2 Special functions
33 //
34 
35 // Written by Edward Smith-Rowland based on numerous mathematics books.
36 
37 #ifndef _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H
38 #define _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H 1
39 
40 namespace std
41 {
42 namespace tr1
43 {
44 
45  namespace __detail
46  {
47 
48  /// A class to encapsulate type dependent floating point
49  /// constants. Not everything will be able to be expressed as
50  /// type logic.
51  template<typename _Tp>
53  {
54  static const _Tp __value;
55  };
56 
57 
58  /// A structure for numeric constants.
59  template<typename _Tp>
61  {
62  /// Constant @f$ \pi @f$.
63  static _Tp __pi() throw()
64  { return static_cast<_Tp>(3.1415926535897932384626433832795029L); }
65  /// Constant @f$ \pi / 2 @f$.
66  static _Tp __pi_2() throw()
67  { return static_cast<_Tp>(1.5707963267948966192313216916397514L); }
68  /// Constant @f$ \pi / 3 @f$.
69  static _Tp __pi_3() throw()
70  { return static_cast<_Tp>(1.0471975511965977461542144610931676L); }
71  /// Constant @f$ \pi / 4 @f$.
72  static _Tp __pi_4() throw()
73  { return static_cast<_Tp>(0.7853981633974483096156608458198757L); }
74  /// Constant @f$ 1 / \pi @f$.
75  static _Tp __1_pi() throw()
76  { return static_cast<_Tp>(0.3183098861837906715377675267450287L); }
77  /// Constant @f$ 2 / \sqrt(\pi) @f$.
78  static _Tp __2_sqrtpi() throw()
79  { return static_cast<_Tp>(1.1283791670955125738961589031215452L); }
80  /// Constant @f$ \sqrt(2) @f$.
81  static _Tp __sqrt2() throw()
82  { return static_cast<_Tp>(1.4142135623730950488016887242096981L); }
83  /// Constant @f$ \sqrt(3) @f$.
84  static _Tp __sqrt3() throw()
85  { return static_cast<_Tp>(1.7320508075688772935274463415058723L); }
86  /// Constant @f$ \sqrt(\pi/2) @f$.
87  static _Tp __sqrtpio2() throw()
88  { return static_cast<_Tp>(1.2533141373155002512078826424055226L); }
89  /// Constant @f$ 1 / sqrt(2) @f$.
90  static _Tp __sqrt1_2() throw()
91  { return static_cast<_Tp>(0.7071067811865475244008443621048490L); }
92  /// Constant @f$ \log(\pi) @f$.
93  static _Tp __lnpi() throw()
94  { return static_cast<_Tp>(1.1447298858494001741434273513530587L); }
95  /// Constant Euler's constant @f$ \gamma_E @f$.
96  static _Tp __gamma_e() throw()
97  { return static_cast<_Tp>(0.5772156649015328606065120900824024L); }
98  /// Constant Euler-Mascheroni @f$ e @f$
99  static _Tp __euler() throw()
100  { return static_cast<_Tp>(2.7182818284590452353602874713526625L); }
101  };
102 
103 
104 #if _GLIBCXX_USE_C99_MATH && !_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC
105 
106  /// This is a wrapper for the isnan function. Otherwise, for NaN,
107  /// all comparisons result in false. If/when we build a std::isnan
108  /// out of intrinsics, this will disappear completely in favor of
109  /// std::isnan.
110  template<typename _Tp>
111  inline bool __isnan(const _Tp __x)
112  {
113  return std::isnan(__x);
114  }
115 
116 #else
117 
118  template<typename _Tp>
119  inline bool __isnan(const _Tp __x)
120  {
121  return __builtin_isnan(__x);
122  }
123 
124  template<>
125  inline bool __isnan<float>(const float __x)
126  {
127  return __builtin_isnanf(__x);
128  }
129 
130  template<>
131  inline bool __isnan<long double>(const long double __x)
132  {
133  return __builtin_isnanl(__x);
134  }
135 
136 #endif
137 
138  } // namespace __detail
139 
140 }
141 }
142 
143 #endif // _GLIBCXX_TR1_SPECIAL_FUNCTION_UTIL_H
144