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132 lines
4.5 KiB
C++
132 lines
4.5 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___RANDOM_STUDENT_T_DISTRIBUTION_H
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#define _LIBCPP___RANDOM_STUDENT_T_DISTRIBUTION_H
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#include <__config>
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#include <__random/gamma_distribution.h>
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#include <__random/is_valid.h>
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#include <__random/normal_distribution.h>
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#include <cmath>
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#include <iosfwd>
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#include <limits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _RealType = double>
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class _LIBCPP_TEMPLATE_VIS student_t_distribution {
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static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,
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"RealType must be a supported floating-point type");
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public:
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// types
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typedef _RealType result_type;
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class _LIBCPP_TEMPLATE_VIS param_type {
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result_type __n_;
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public:
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typedef student_t_distribution distribution_type;
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_LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __n = 1) : __n_(__n) {}
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_LIBCPP_HIDE_FROM_ABI result_type n() const { return __n_; }
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friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
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return __x.__n_ == __y.__n_;
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}
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friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
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};
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private:
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param_type __p_;
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normal_distribution<result_type> __nd_;
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public:
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// constructor and reset functions
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_HIDE_FROM_ABI student_t_distribution() : student_t_distribution(1) {}
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_LIBCPP_HIDE_FROM_ABI explicit student_t_distribution(result_type __n) : __p_(param_type(__n)) {}
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#else
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_LIBCPP_HIDE_FROM_ABI explicit student_t_distribution(result_type __n = 1) : __p_(param_type(__n)) {}
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#endif
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_LIBCPP_HIDE_FROM_ABI explicit student_t_distribution(const param_type& __p) : __p_(__p) {}
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_LIBCPP_HIDE_FROM_ABI void reset() { __nd_.reset(); }
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// generating functions
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template <class _URNG>
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_LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
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return (*this)(__g, __p_);
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}
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template <class _URNG>
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_LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
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// property functions
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_LIBCPP_HIDE_FROM_ABI result_type n() const { return __p_.n(); }
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_LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
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_LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
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_LIBCPP_HIDE_FROM_ABI result_type min() const { return -numeric_limits<result_type>::infinity(); }
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_LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }
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friend _LIBCPP_HIDE_FROM_ABI bool operator==(const student_t_distribution& __x, const student_t_distribution& __y) {
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return __x.__p_ == __y.__p_;
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}
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friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const student_t_distribution& __x, const student_t_distribution& __y) {
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return !(__x == __y);
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}
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};
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template <class _RealType>
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template <class _URNG>
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_RealType student_t_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {
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static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
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gamma_distribution<result_type> __gd(__p.n() * .5, 2);
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return __nd_(__g) * std::sqrt(__p.n() / __gd(__g));
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}
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template <class _CharT, class _Traits, class _RT>
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_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os, const student_t_distribution<_RT>& __x) {
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__save_flags<_CharT, _Traits> __lx(__os);
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typedef basic_ostream<_CharT, _Traits> _OStream;
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__os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
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__os << __x.n();
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return __os;
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}
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template <class _CharT, class _Traits, class _RT>
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_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is, student_t_distribution<_RT>& __x) {
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typedef student_t_distribution<_RT> _Eng;
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typedef typename _Eng::result_type result_type;
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typedef typename _Eng::param_type param_type;
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__save_flags<_CharT, _Traits> __lx(__is);
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typedef basic_istream<_CharT, _Traits> _Istream;
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__is.flags(_Istream::dec | _Istream::skipws);
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result_type __n;
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__is >> __n;
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if (!__is.fail())
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__x.param(param_type(__n));
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return __is;
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANDOM_STUDENT_T_DISTRIBUTION_H
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