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1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___CXX03___RANDOM_NORMAL_DISTRIBUTION_H
10#define _LIBCPP___CXX03___RANDOM_NORMAL_DISTRIBUTION_H
11
12#include <__cxx03/__config>
13#include <__cxx03/__random/is_valid.h>
14#include <__cxx03/__random/uniform_real_distribution.h>
15#include <__cxx03/cmath>
16#include <__cxx03/iosfwd>
17#include <__cxx03/limits>
18
19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20# pragma GCC system_header
21#endif
22
23_LIBCPP_PUSH_MACROS
24#include <__cxx03/__undef_macros>
25
26_LIBCPP_BEGIN_NAMESPACE_STD
27
28template <class _RealType = double>
29class _LIBCPP_TEMPLATE_VIS normal_distribution {
30 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
31 "RealType must be a supported floating-point type");
32
33public:
34 // types
35 typedef _RealType result_type;
36
37 class _LIBCPP_TEMPLATE_VIS param_type {
38 result_type __mean_;
39 result_type __stddev_;
40
41 public:
42 typedef normal_distribution distribution_type;
43
44 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __mean = 0, result_type __stddev = 1)
45 : __mean_(__mean), __stddev_(__stddev) {}
46
47 _LIBCPP_HIDE_FROM_ABI result_type mean() const { return __mean_; }
48 _LIBCPP_HIDE_FROM_ABI result_type stddev() const { return __stddev_; }
49
50 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
51 return __x.__mean_ == __y.__mean_ && __x.__stddev_ == __y.__stddev_;
52 }
53 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
54 };
55
56private:
57 param_type __p_;
58 result_type __v_;
59 bool __v_hot_;
60
61public:
62 // constructors and reset functions
63 _LIBCPP_HIDE_FROM_ABI explicit normal_distribution(result_type __mean = 0, result_type __stddev = 1)
64 : __p_(param_type(__mean, __stddev)), __v_hot_(false) {}
65 _LIBCPP_HIDE_FROM_ABI explicit normal_distribution(const param_type& __p) : __p_(__p), __v_hot_(false) {}
66 _LIBCPP_HIDE_FROM_ABI void reset() { __v_hot_ = false; }
67
68 // generating functions
69 template <class _URNG>
70 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
71 return (*this)(__g, __p_);
72 }
73 template <class _URNG>
74 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
75
76 // property functions
77 _LIBCPP_HIDE_FROM_ABI result_type mean() const { return __p_.mean(); }
78 _LIBCPP_HIDE_FROM_ABI result_type stddev() const { return __p_.stddev(); }
79
80 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
81 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
82
83 _LIBCPP_HIDE_FROM_ABI result_type min() const { return -numeric_limits<result_type>::infinity(); }
84 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }
85
86 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const normal_distribution& __x, const normal_distribution& __y) {
87 return __x.__p_ == __y.__p_ && __x.__v_hot_ == __y.__v_hot_ && (!__x.__v_hot_ || __x.__v_ == __y.__v_);
88 }
89 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const normal_distribution& __x, const normal_distribution& __y) {
90 return !(__x == __y);
91 }
92
93 template <class _CharT, class _Traits, class _RT>
94 friend basic_ostream<_CharT, _Traits>&
95 operator<<(basic_ostream<_CharT, _Traits>& __os, const normal_distribution<_RT>& __x);
96
97 template <class _CharT, class _Traits, class _RT>
98 friend basic_istream<_CharT, _Traits>&
99 operator>>(basic_istream<_CharT, _Traits>& __is, normal_distribution<_RT>& __x);
100};
101
102template <class _RealType>
103template <class _URNG>
104_RealType normal_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
105 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
106 result_type __up;
107 if (__v_hot_) {
108 __v_hot_ = false;
109 __up = __v_;
110 } else {
111 uniform_real_distribution<result_type> __uni(-1, 1);
112 result_type __u;
113 result_type __v;
114 result_type __s;
115 do {
116 __u = __uni(__g);
117 __v = __uni(__g);
118 __s = __u * __u + __v * __v;
119 } while (__s > 1 || __s == 0);
120 result_type __fp = std::sqrt(-2 * std::log(__s) / __s);
121 __v_ = __v * __fp;
122 __v_hot_ = true;
123 __up = __u * __fp;
124 }
125 return __up * __p.stddev() + __p.mean();
126}
127
128template <class _CharT, class _Traits, class _RT>
129_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
130operator<<(basic_ostream<_CharT, _Traits>& __os, const normal_distribution<_RT>& __x) {
131 __save_flags<_CharT, _Traits> __lx(__os);
132 typedef basic_ostream<_CharT, _Traits> _OStream;
133 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
134 _CharT __sp = __os.widen(' ');
135 __os.fill(__sp);
136 __os << __x.mean() << __sp << __x.stddev() << __sp << __x.__v_hot_;
137 if (__x.__v_hot_)
138 __os << __sp << __x.__v_;
139 return __os;
140}
141
142template <class _CharT, class _Traits, class _RT>
143_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
144operator>>(basic_istream<_CharT, _Traits>& __is, normal_distribution<_RT>& __x) {
145 typedef normal_distribution<_RT> _Eng;
146 typedef typename _Eng::result_type result_type;
147 typedef typename _Eng::param_type param_type;
148 __save_flags<_CharT, _Traits> __lx(__is);
149 typedef basic_istream<_CharT, _Traits> _Istream;
150 __is.flags(_Istream::dec | _Istream::skipws);
151 result_type __mean;
152 result_type __stddev;
153 result_type __vp = 0;
154 bool __v_hot = false;
155 __is >> __mean >> __stddev >> __v_hot;
156 if (__v_hot)
157 __is >> __vp;
158 if (!__is.fail()) {
159 __x.param(param_type(__mean, __stddev));
160 __x.__v_hot_ = __v_hot;
161 __x.__v_ = __vp;
162 }
163 return __is;
164}
165
166_LIBCPP_END_NAMESPACE_STD
167
168_LIBCPP_POP_MACROS
169
170#endif // _LIBCPP___CXX03___RANDOM_NORMAL_DISTRIBUTION_H
171

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source code of libcxx/include/__cxx03/__random/normal_distribution.h