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