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___RANDOM_NORMAL_DISTRIBUTION_H 10 #define _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H 11 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_header 21 #endif 22 23 _LIBCPP_PUSH_MACROS 24 #include <__undef_macros> 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 template <class _RealType = double> 29 class _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 33 public: 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 56 private: 57 param_type __p_; 58 result_type __v_; 59 bool __v_hot_; 60 61 public: 62 // constructors and reset functions 63 #ifndef _LIBCPP_CXX03_LANG 64 _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 #else 68 _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 #endif 71 _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 functions 75 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 functions 83 _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 }; 107 108 template <class _RealType> 109 template <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 } 133 134 template <class _CharT, class _Traits, class _RT> 135 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& 136 operator<<(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 } 147 148 template <class _CharT, class _Traits, class _RT> 149 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& 150 operator>>(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_STD 173 174 _LIBCPP_POP_MACROS 175 176 #endif // _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H 177