libstdc++
numeric
Go to the documentation of this file.
1 // <numeric> -*- C++ -*-
2 
3 // Copyright (C) 2001-2018 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 /*
26  *
27  * Copyright (c) 1994
28  * Hewlett-Packard Company
29  *
30  * Permission to use, copy, modify, distribute and sell this software
31  * and its documentation for any purpose is hereby granted without fee,
32  * provided that the above copyright notice appear in all copies and
33  * that both that copyright notice and this permission notice appear
34  * in supporting documentation. Hewlett-Packard Company makes no
35  * representations about the suitability of this software for any
36  * purpose. It is provided "as is" without express or implied warranty.
37  *
38  *
39  * Copyright (c) 1996,1997
40  * Silicon Graphics Computer Systems, Inc.
41  *
42  * Permission to use, copy, modify, distribute and sell this software
43  * and its documentation for any purpose is hereby granted without fee,
44  * provided that the above copyright notice appear in all copies and
45  * that both that copyright notice and this permission notice appear
46  * in supporting documentation. Silicon Graphics makes no
47  * representations about the suitability of this software for any
48  * purpose. It is provided "as is" without express or implied warranty.
49  */
50 
51 /** @file include/numeric
52  * This is a Standard C++ Library header.
53  */
54 
55 #ifndef _GLIBCXX_NUMERIC
56 #define _GLIBCXX_NUMERIC 1
57 
58 #pragma GCC system_header
59 
60 #include <bits/c++config.h>
61 #include <bits/stl_iterator_base_types.h>
62 #include <bits/stl_numeric.h>
63 #include <ext/numeric_traits.h>
64 
65 #ifdef _GLIBCXX_PARALLEL
66 # include <parallel/numeric>
67 #endif
68 
69 /**
70  * @defgroup numerics Numerics
71  *
72  * Components for performing numeric operations. Includes support for
73  * for complex number types, random number generation, numeric
74  * (n-at-a-time) arrays, generalized numeric algorithms, and special
75  * math functions.
76  */
77 
78 #if __cplusplus >= 201402L
79 #include <type_traits>
80 
81 namespace std _GLIBCXX_VISIBILITY(default)
82 {
83 _GLIBCXX_BEGIN_NAMESPACE_VERSION
84 
85 namespace __detail
86 {
87  // std::abs is not constexpr, doesn't support unsigned integers,
88  // and std::abs(std::numeric_limits<T>::min()) is undefined.
89  template<typename _Up, typename _Tp>
90  constexpr _Up
91  __absu(_Tp __val)
92  {
93  static_assert(is_unsigned<_Up>::value, "result type must be unsigned");
94  static_assert(sizeof(_Up) >= sizeof(_Tp),
95  "result type must be at least as wide as the input type");
96  return __val < 0 ? -(_Up)__val : (_Up)__val;
97  }
98 
99  template<typename _Up> void __absu(bool) = delete;
100 
101  // GCD implementation
102  template<typename _Tp>
103  constexpr _Tp
104  __gcd(_Tp __m, _Tp __n)
105  {
106  static_assert(is_unsigned<_Tp>::value, "type must be unsigned");
107  return __m == 0 ? __n
108  : __n == 0 ? __m
109  : __detail::__gcd(__n, _Tp(__m % __n));
110  }
111 
112  // LCM implementation
113  template<typename _Tp>
114  constexpr _Tp
115  __lcm(_Tp __m, _Tp __n)
116  {
117  return (__m != 0 && __n != 0)
118  ? (__m / __detail::__gcd(__m, __n)) * __n
119  : 0;
120  }
121 } // namespace __detail
122 
123 #if __cplusplus > 201402L
124 
125 #define __cpp_lib_gcd_lcm 201606
126 // These were used in drafts of SD-6:
127 #define __cpp_lib_gcd 201606
128 #define __cpp_lib_lcm 201606
129 
130  /// Greatest common divisor
131  template<typename _Mn, typename _Nn>
132  constexpr common_type_t<_Mn, _Nn>
133  gcd(_Mn __m, _Nn __n) noexcept
134  {
135  static_assert(is_integral_v<_Mn>, "std::gcd arguments must be integers");
136  static_assert(is_integral_v<_Nn>, "std::gcd arguments must be integers");
137  static_assert(_Mn(2) != _Mn(1), "std::gcd arguments must not be bool");
138  static_assert(_Nn(2) != _Nn(1), "std::gcd arguments must not be bool");
139  using _Up = make_unsigned_t<common_type_t<_Mn, _Nn>>;
140  return __detail::__gcd(__detail::__absu<_Up>(__m),
141  __detail::__absu<_Up>(__n));
142  }
143 
144  /// Least common multiple
145  template<typename _Mn, typename _Nn>
146  constexpr common_type_t<_Mn, _Nn>
147  lcm(_Mn __m, _Nn __n) noexcept
148  {
149  static_assert(is_integral_v<_Mn>, "std::lcm arguments must be integers");
150  static_assert(is_integral_v<_Nn>, "std::lcm arguments must be integers");
151  static_assert(_Mn(2) == 2, "std::lcm arguments must not be bool");
152  static_assert(_Nn(2) == 2, "std::lcm arguments must not be bool");
153  using _Up = make_unsigned_t<common_type_t<_Mn, _Nn>>;
154  return __detail::__lcm(__detail::__absu<_Up>(__m),
155  __detail::__absu<_Up>(__n));
156  }
157 
158 #endif // C++17
159 
160 _GLIBCXX_END_NAMESPACE_VERSION
161 } // namespace std
162 
163 #endif // C++14
164 
165 
166 #endif /* _GLIBCXX_NUMERIC */