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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_CHI_SQUARED_DISTRIBUTION_H10#define _LIBCPP___RANDOM_CHI_SQUARED_DISTRIBUTION_H11 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_header20#endif21 22_LIBCPP_PUSH_MACROS23#include <__undef_macros>24 25_LIBCPP_BEGIN_NAMESPACE_STD26 27template <class _RealType = double>28class chi_squared_distribution {29 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,30 "RealType must be a supported floating-point type");31 32public:33 // types34 typedef _RealType result_type;35 36 class 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 52private:53 param_type __p_;54 55public:56 // constructor and reset functions57#ifndef _LIBCPP_CXX03_LANG58 _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#else61 _LIBCPP_HIDE_FROM_ABI explicit chi_squared_distribution(result_type __n = 1) : __p_(param_type(__n)) {}62#endif63 _LIBCPP_HIDE_FROM_ABI explicit chi_squared_distribution(const param_type& __p) : __p_(__p) {}64 _LIBCPP_HIDE_FROM_ABI void reset() {}65 66 // generating functions67 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 functions77 _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 bool86 operator==(const chi_squared_distribution& __x, const chi_squared_distribution& __y) {87 return __x.__p_ == __y.__p_;88 }89 friend _LIBCPP_HIDE_FROM_ABI bool90 operator!=(const chi_squared_distribution& __x, const chi_squared_distribution& __y) {91 return !(__x == __y);92 }93};94 95template <class _CharT, class _Traits, class _RT>96_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&97operator<<(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 105template <class _CharT, class _Traits, class _RT>106_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&107operator>>(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_STD122 123_LIBCPP_POP_MACROS124 125#endif // _LIBCPP___RANDOM_CHI_SQUARED_DISTRIBUTION_H126