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