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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___CXX03___RANDOM_NORMAL_DISTRIBUTION_H10#define _LIBCPP___CXX03___RANDOM_NORMAL_DISTRIBUTION_H11 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_header21#endif22 23_LIBCPP_PUSH_MACROS24#include <__cxx03/__undef_macros>25 26_LIBCPP_BEGIN_NAMESPACE_STD27 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 // types35 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 functions63 _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 functions69 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 functions77 _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_STD167 168_LIBCPP_POP_MACROS169 170#endif // _LIBCPP___CXX03___RANDOM_NORMAL_DISTRIBUTION_H171