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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___RANDOM_NORMAL_DISTRIBUTION_H10#define _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H11 12#include <__config>13#include <__random/is_valid.h>14#include <__random/uniform_real_distribution.h>15#include <cmath>16#include <iosfwd>17#include <limits>18 19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)20# pragma GCC system_header21#endif22 23_LIBCPP_PUSH_MACROS24#include <__undef_macros>25 26_LIBCPP_BEGIN_NAMESPACE_STD27 28template <class _RealType = double>29class 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 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#ifndef _LIBCPP_CXX03_LANG64 _LIBCPP_HIDE_FROM_ABI normal_distribution() : normal_distribution(0) {}65 _LIBCPP_HIDE_FROM_ABI explicit normal_distribution(result_type __mean, result_type __stddev = 1)66 : __p_(param_type(__mean, __stddev)), __v_hot_(false) {}67#else68 _LIBCPP_HIDE_FROM_ABI explicit normal_distribution(result_type __mean = 0, result_type __stddev = 1)69 : __p_(param_type(__mean, __stddev)), __v_hot_(false) {}70#endif71 _LIBCPP_HIDE_FROM_ABI explicit normal_distribution(const param_type& __p) : __p_(__p), __v_hot_(false) {}72 _LIBCPP_HIDE_FROM_ABI void reset() { __v_hot_ = false; }73 74 // generating functions75 template <class _URNG>76 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {77 return (*this)(__g, __p_);78 }79 template <class _URNG>80 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);81 82 // property functions83 _LIBCPP_HIDE_FROM_ABI result_type mean() const { return __p_.mean(); }84 _LIBCPP_HIDE_FROM_ABI result_type stddev() const { return __p_.stddev(); }85 86 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }87 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }88 89 _LIBCPP_HIDE_FROM_ABI result_type min() const { return -numeric_limits<result_type>::infinity(); }90 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }91 92 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const normal_distribution& __x, const normal_distribution& __y) {93 return __x.__p_ == __y.__p_ && __x.__v_hot_ == __y.__v_hot_ && (!__x.__v_hot_ || __x.__v_ == __y.__v_);94 }95 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const normal_distribution& __x, const normal_distribution& __y) {96 return !(__x == __y);97 }98 99 template <class _CharT, class _Traits, class _RT>100 friend basic_ostream<_CharT, _Traits>&101 operator<<(basic_ostream<_CharT, _Traits>& __os, const normal_distribution<_RT>& __x);102 103 template <class _CharT, class _Traits, class _RT>104 friend basic_istream<_CharT, _Traits>&105 operator>>(basic_istream<_CharT, _Traits>& __is, normal_distribution<_RT>& __x);106};107 108template <class _RealType>109template <class _URNG>110_RealType normal_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {111 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");112 result_type __up;113 if (__v_hot_) {114 __v_hot_ = false;115 __up = __v_;116 } else {117 uniform_real_distribution<result_type> __uni(-1, 1);118 result_type __u;119 result_type __v;120 result_type __s;121 do {122 __u = __uni(__g);123 __v = __uni(__g);124 __s = __u * __u + __v * __v;125 } while (__s > 1 || __s == 0);126 result_type __fp = std::sqrt(-2 * std::log(__s) / __s);127 __v_ = __v * __fp;128 __v_hot_ = true;129 __up = __u * __fp;130 }131 return __up * __p.stddev() + __p.mean();132}133 134template <class _CharT, class _Traits, class _RT>135_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&136operator<<(basic_ostream<_CharT, _Traits>& __os, const normal_distribution<_RT>& __x) {137 __save_flags<_CharT, _Traits> __lx(__os);138 typedef basic_ostream<_CharT, _Traits> _OStream;139 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);140 _CharT __sp = __os.widen(' ');141 __os.fill(__sp);142 __os << __x.mean() << __sp << __x.stddev() << __sp << __x.__v_hot_;143 if (__x.__v_hot_)144 __os << __sp << __x.__v_;145 return __os;146}147 148template <class _CharT, class _Traits, class _RT>149_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&150operator>>(basic_istream<_CharT, _Traits>& __is, normal_distribution<_RT>& __x) {151 typedef normal_distribution<_RT> _Eng;152 typedef typename _Eng::result_type result_type;153 typedef typename _Eng::param_type param_type;154 __save_flags<_CharT, _Traits> __lx(__is);155 typedef basic_istream<_CharT, _Traits> _Istream;156 __is.flags(_Istream::dec | _Istream::skipws);157 result_type __mean;158 result_type __stddev;159 result_type __vp = 0;160 bool __v_hot = false;161 __is >> __mean >> __stddev >> __v_hot;162 if (__v_hot)163 __is >> __vp;164 if (!__is.fail()) {165 __x.param(param_type(__mean, __stddev));166 __x.__v_hot_ = __v_hot;167 __x.__v_ = __vp;168 }169 return __is;170}171 172_LIBCPP_END_NAMESPACE_STD173 174_LIBCPP_POP_MACROS175 176#endif // _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H177