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___CXX03___RANDOM_CHI_SQUARED_DISTRIBUTION_H 10 #define _LIBCPP___CXX03___RANDOM_CHI_SQUARED_DISTRIBUTION_H 11 12 #include <__cxx03/__config> 13 #include <__cxx03/__random/gamma_distribution.h> 14 #include <__cxx03/__random/is_valid.h> 15 #include <__cxx03/iosfwd> 16 #include <__cxx03/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 <__cxx03/__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 __n_(__n)42 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __n = 1) : __n_(__n) {} 43 n()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 __p_(param_type (__n))57 _LIBCPP_HIDE_FROM_ABI explicit chi_squared_distribution(result_type __n = 1) : __p_(param_type(__n)) {} chi_squared_distribution(const param_type & __p)58 _LIBCPP_HIDE_FROM_ABI explicit chi_squared_distribution(const param_type& __p) : __p_(__p) {} reset()59 _LIBCPP_HIDE_FROM_ABI void reset() {} 60 61 // generating functions 62 template <class _URNG> operator()63 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) { 64 return (*this)(__g, __p_); 65 } 66 template <class _URNG> operator()67 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p) { 68 return gamma_distribution<result_type>(__p.n() / 2, 2)(__g); 69 } 70 71 // property functions n()72 _LIBCPP_HIDE_FROM_ABI result_type n() const { return __p_.n(); } 73 param()74 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; } param(const param_type & __p)75 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; } 76 min()77 _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; } max()78 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); } 79 80 friend _LIBCPP_HIDE_FROM_ABI bool 81 operator==(const chi_squared_distribution& __x, const chi_squared_distribution& __y) { 82 return __x.__p_ == __y.__p_; 83 } 84 friend _LIBCPP_HIDE_FROM_ABI bool 85 operator!=(const chi_squared_distribution& __x, const chi_squared_distribution& __y) { 86 return !(__x == __y); 87 } 88 }; 89 90 template <class _CharT, class _Traits, class _RT> 91 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& 92 operator<<(basic_ostream<_CharT, _Traits>& __os, const chi_squared_distribution<_RT>& __x) { 93 __save_flags<_CharT, _Traits> __lx(__os); 94 typedef basic_ostream<_CharT, _Traits> _OStream; 95 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific); 96 __os << __x.n(); 97 return __os; 98 } 99 100 template <class _CharT, class _Traits, class _RT> 101 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& 102 operator>>(basic_istream<_CharT, _Traits>& __is, chi_squared_distribution<_RT>& __x) { 103 typedef chi_squared_distribution<_RT> _Eng; 104 typedef typename _Eng::result_type result_type; 105 typedef typename _Eng::param_type param_type; 106 __save_flags<_CharT, _Traits> __lx(__is); 107 typedef basic_istream<_CharT, _Traits> _Istream; 108 __is.flags(_Istream::dec | _Istream::skipws); 109 result_type __n; 110 __is >> __n; 111 if (!__is.fail()) 112 __x.param(param_type(__n)); 113 return __is; 114 } 115 116 _LIBCPP_END_NAMESPACE_STD 117 118 _LIBCPP_POP_MACROS 119 120 #endif // _LIBCPP___CXX03___RANDOM_CHI_SQUARED_DISTRIBUTION_H 121