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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_STUDENT_T_DISTRIBUTION_H10#define _LIBCPP___RANDOM_STUDENT_T_DISTRIBUTION_H11 12#include <__config>13#include <__random/gamma_distribution.h>14#include <__random/is_valid.h>15#include <__random/normal_distribution.h>16#include <cmath>17#include <iosfwd>18#include <limits>19 20#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)21# pragma GCC system_header22#endif23 24_LIBCPP_PUSH_MACROS25#include <__undef_macros>26 27_LIBCPP_BEGIN_NAMESPACE_STD28 29template <class _RealType = double>30class student_t_distribution {31 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,32 "RealType must be a supported floating-point type");33 34public:35 // types36 typedef _RealType result_type;37 38 class param_type {39 result_type __n_;40 41 public:42 typedef student_t_distribution distribution_type;43 44 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __n = 1) : __n_(__n) {}45 46 _LIBCPP_HIDE_FROM_ABI result_type n() const { return __n_; }47 48 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {49 return __x.__n_ == __y.__n_;50 }51 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }52 };53 54private:55 param_type __p_;56 normal_distribution<result_type> __nd_;57 58public:59 // constructor and reset functions60#ifndef _LIBCPP_CXX03_LANG61 _LIBCPP_HIDE_FROM_ABI student_t_distribution() : student_t_distribution(1) {}62 _LIBCPP_HIDE_FROM_ABI explicit student_t_distribution(result_type __n) : __p_(param_type(__n)) {}63#else64 _LIBCPP_HIDE_FROM_ABI explicit student_t_distribution(result_type __n = 1) : __p_(param_type(__n)) {}65#endif66 _LIBCPP_HIDE_FROM_ABI explicit student_t_distribution(const param_type& __p) : __p_(__p) {}67 _LIBCPP_HIDE_FROM_ABI void reset() { __nd_.reset(); }68 69 // generating functions70 template <class _URNG>71 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {72 return (*this)(__g, __p_);73 }74 template <class _URNG>75 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);76 77 // property functions78 _LIBCPP_HIDE_FROM_ABI result_type n() const { return __p_.n(); }79 80 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }81 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }82 83 _LIBCPP_HIDE_FROM_ABI result_type min() const { return -numeric_limits<result_type>::infinity(); }84 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }85 86 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const student_t_distribution& __x, const student_t_distribution& __y) {87 return __x.__p_ == __y.__p_;88 }89 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const student_t_distribution& __x, const student_t_distribution& __y) {90 return !(__x == __y);91 }92};93 94template <class _RealType>95template <class _URNG>96_RealType student_t_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {97 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");98 gamma_distribution<result_type> __gd(__p.n() * .5, 2);99 return __nd_(__g) * std::sqrt(__p.n() / __gd(__g));100}101 102template <class _CharT, class _Traits, class _RT>103_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&104operator<<(basic_ostream<_CharT, _Traits>& __os, const student_t_distribution<_RT>& __x) {105 __save_flags<_CharT, _Traits> __lx(__os);106 typedef basic_ostream<_CharT, _Traits> _OStream;107 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);108 __os << __x.n();109 return __os;110}111 112template <class _CharT, class _Traits, class _RT>113_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&114operator>>(basic_istream<_CharT, _Traits>& __is, student_t_distribution<_RT>& __x) {115 typedef student_t_distribution<_RT> _Eng;116 typedef typename _Eng::result_type result_type;117 typedef typename _Eng::param_type param_type;118 __save_flags<_CharT, _Traits> __lx(__is);119 typedef basic_istream<_CharT, _Traits> _Istream;120 __is.flags(_Istream::dec | _Istream::skipws);121 result_type __n;122 __is >> __n;123 if (!__is.fail())124 __x.param(param_type(__n));125 return __is;126}127 128_LIBCPP_END_NAMESPACE_STD129 130_LIBCPP_POP_MACROS131 132#endif // _LIBCPP___RANDOM_STUDENT_T_DISTRIBUTION_H133