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_CHI_SQUARED_DISTRIBUTION_H 10 #define _LIBCPP___RANDOM_CHI_SQUARED_DISTRIBUTION_H 11 12 #include <__config> 13 #include <__random/gamma_distribution.h> 14 #include <iosfwd> 15 #include <limits> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_PUSH_MACROS 22 #include <__undef_macros> 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 template<class _RealType = double> 27 class _LIBCPP_TEMPLATE_VIS chi_squared_distribution 28 { 29 public: 30 // types 31 typedef _RealType result_type; 32 33 class _LIBCPP_TEMPLATE_VIS param_type 34 { 35 result_type __n_; 36 public: 37 typedef chi_squared_distribution distribution_type; 38 39 _LIBCPP_INLINE_VISIBILITY 40 explicit param_type(result_type __n = 1) : __n_(__n) {} 41 42 _LIBCPP_INLINE_VISIBILITY 43 result_type n() const {return __n_;} 44 45 friend _LIBCPP_INLINE_VISIBILITY 46 bool operator==(const param_type& __x, const param_type& __y) 47 {return __x.__n_ == __y.__n_;} 48 friend _LIBCPP_INLINE_VISIBILITY 49 bool operator!=(const param_type& __x, const param_type& __y) 50 {return !(__x == __y);} 51 }; 52 53 private: 54 param_type __p_; 55 56 public: 57 // constructor and reset functions 58 #ifndef _LIBCPP_CXX03_LANG 59 _LIBCPP_INLINE_VISIBILITY 60 chi_squared_distribution() : chi_squared_distribution(1) {} 61 _LIBCPP_INLINE_VISIBILITY 62 explicit chi_squared_distribution(result_type __n) 63 : __p_(param_type(__n)) {} 64 #else 65 _LIBCPP_INLINE_VISIBILITY 66 explicit chi_squared_distribution(result_type __n = 1) 67 : __p_(param_type(__n)) {} 68 #endif 69 _LIBCPP_INLINE_VISIBILITY 70 explicit chi_squared_distribution(const param_type& __p) 71 : __p_(__p) {} 72 _LIBCPP_INLINE_VISIBILITY 73 void reset() {} 74 75 // generating functions 76 template<class _URNG> 77 _LIBCPP_INLINE_VISIBILITY 78 result_type operator()(_URNG& __g) 79 {return (*this)(__g, __p_);} 80 template<class _URNG> 81 _LIBCPP_INLINE_VISIBILITY 82 result_type operator()(_URNG& __g, const param_type& __p) 83 {return gamma_distribution<result_type>(__p.n() / 2, 2)(__g);} 84 85 // property functions 86 _LIBCPP_INLINE_VISIBILITY 87 result_type n() const {return __p_.n();} 88 89 _LIBCPP_INLINE_VISIBILITY 90 param_type param() const {return __p_;} 91 _LIBCPP_INLINE_VISIBILITY 92 void param(const param_type& __p) {__p_ = __p;} 93 94 _LIBCPP_INLINE_VISIBILITY 95 result_type min() const {return 0;} 96 _LIBCPP_INLINE_VISIBILITY 97 result_type max() const {return numeric_limits<result_type>::infinity();} 98 99 friend _LIBCPP_INLINE_VISIBILITY 100 bool operator==(const chi_squared_distribution& __x, 101 const chi_squared_distribution& __y) 102 {return __x.__p_ == __y.__p_;} 103 friend _LIBCPP_INLINE_VISIBILITY 104 bool operator!=(const chi_squared_distribution& __x, 105 const chi_squared_distribution& __y) 106 {return !(__x == __y);} 107 }; 108 109 template <class _CharT, class _Traits, class _RT> 110 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& 111 operator<<(basic_ostream<_CharT, _Traits>& __os, 112 const chi_squared_distribution<_RT>& __x) 113 { 114 __save_flags<_CharT, _Traits> __lx(__os); 115 typedef basic_ostream<_CharT, _Traits> _OStream; 116 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | 117 _OStream::scientific); 118 __os << __x.n(); 119 return __os; 120 } 121 122 template <class _CharT, class _Traits, class _RT> 123 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& 124 operator>>(basic_istream<_CharT, _Traits>& __is, 125 chi_squared_distribution<_RT>& __x) 126 { 127 typedef chi_squared_distribution<_RT> _Eng; 128 typedef typename _Eng::result_type result_type; 129 typedef typename _Eng::param_type param_type; 130 __save_flags<_CharT, _Traits> __lx(__is); 131 typedef basic_istream<_CharT, _Traits> _Istream; 132 __is.flags(_Istream::dec | _Istream::skipws); 133 result_type __n; 134 __is >> __n; 135 if (!__is.fail()) 136 __x.param(param_type(__n)); 137 return __is; 138 } 139 140 _LIBCPP_END_NAMESPACE_STD 141 142 _LIBCPP_POP_MACROS 143 144 #endif // _LIBCPP___RANDOM_CHI_SQUARED_DISTRIBUTION_H 145