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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H
#define _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H
#include <__config>
#include <__random/is_valid.h>
#include <__random/uniform_real_distribution.h>
#include <cmath>
#include <iosfwd>
#include <limits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
template<class _RealType = double>
class _LIBCPP_TEMPLATE_VIS normal_distribution
{
public:
// types
typedef _RealType result_type;
class _LIBCPP_TEMPLATE_VIS param_type
{
result_type __mean_;
result_type __stddev_;
public:
typedef normal_distribution distribution_type;
_LIBCPP_INLINE_VISIBILITY
explicit param_type(result_type __mean = 0, result_type __stddev = 1)
: __mean_(__mean), __stddev_(__stddev) {}
_LIBCPP_INLINE_VISIBILITY
result_type mean() const {return __mean_;}
_LIBCPP_INLINE_VISIBILITY
result_type stddev() const {return __stddev_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator==(const param_type& __x, const param_type& __y)
{return __x.__mean_ == __y.__mean_ && __x.__stddev_ == __y.__stddev_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator!=(const param_type& __x, const param_type& __y)
{return !(__x == __y);}
};
private:
param_type __p_;
result_type _V_;
bool _V_hot_;
public:
// constructors and reset functions
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY
normal_distribution() : normal_distribution(0) {}
_LIBCPP_INLINE_VISIBILITY
explicit normal_distribution(result_type __mean, result_type __stddev = 1)
: __p_(param_type(__mean, __stddev)), _V_hot_(false) {}
#else
_LIBCPP_INLINE_VISIBILITY
explicit normal_distribution(result_type __mean = 0,
result_type __stddev = 1)
: __p_(param_type(__mean, __stddev)), _V_hot_(false) {}
#endif
_LIBCPP_INLINE_VISIBILITY
explicit normal_distribution(const param_type& __p)
: __p_(__p), _V_hot_(false) {}
_LIBCPP_INLINE_VISIBILITY
void reset() {_V_hot_ = false;}
// generating functions
template<class _URNG>
_LIBCPP_INLINE_VISIBILITY
result_type operator()(_URNG& __g)
{return (*this)(__g, __p_);}
template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
// property functions
_LIBCPP_INLINE_VISIBILITY
result_type mean() const {return __p_.mean();}
_LIBCPP_INLINE_VISIBILITY
result_type stddev() const {return __p_.stddev();}
_LIBCPP_INLINE_VISIBILITY
param_type param() const {return __p_;}
_LIBCPP_INLINE_VISIBILITY
void param(const param_type& __p) {__p_ = __p;}
_LIBCPP_INLINE_VISIBILITY
result_type min() const {return -numeric_limits<result_type>::infinity();}
_LIBCPP_INLINE_VISIBILITY
result_type max() const {return numeric_limits<result_type>::infinity();}
friend _LIBCPP_INLINE_VISIBILITY
bool operator==(const normal_distribution& __x,
const normal_distribution& __y)
{return __x.__p_ == __y.__p_ && __x._V_hot_ == __y._V_hot_ &&
(!__x._V_hot_ || __x._V_ == __y._V_);}
friend _LIBCPP_INLINE_VISIBILITY
bool operator!=(const normal_distribution& __x,
const normal_distribution& __y)
{return !(__x == __y);}
template <class _CharT, class _Traits, class _RT>
friend
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
const normal_distribution<_RT>& __x);
template <class _CharT, class _Traits, class _RT>
friend
basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is,
normal_distribution<_RT>& __x);
};
template <class _RealType>
template<class _URNG>
_RealType
normal_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
{
static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
result_type _Up;
if (_V_hot_)
{
_V_hot_ = false;
_Up = _V_;
}
else
{
uniform_real_distribution<result_type> _Uni(-1, 1);
result_type __u;
result_type __v;
result_type __s;
do
{
__u = _Uni(__g);
__v = _Uni(__g);
__s = __u * __u + __v * __v;
} while (__s > 1 || __s == 0);
result_type _Fp = _VSTD::sqrt(-2 * _VSTD::log(__s) / __s);
_V_ = __v * _Fp;
_V_hot_ = true;
_Up = __u * _Fp;
}
return _Up * __p.stddev() + __p.mean();
}
template <class _CharT, class _Traits, class _RT>
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
const normal_distribution<_RT>& __x)
{
__save_flags<_CharT, _Traits> __lx(__os);
typedef basic_ostream<_CharT, _Traits> _OStream;
__os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
_OStream::scientific);
_CharT __sp = __os.widen(' ');
__os.fill(__sp);
__os << __x.mean() << __sp << __x.stddev() << __sp << __x._V_hot_;
if (__x._V_hot_)
__os << __sp << __x._V_;
return __os;
}
template <class _CharT, class _Traits, class _RT>
basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is,
normal_distribution<_RT>& __x)
{
typedef normal_distribution<_RT> _Eng;
typedef typename _Eng::result_type result_type;
typedef typename _Eng::param_type param_type;
__save_flags<_CharT, _Traits> __lx(__is);
typedef basic_istream<_CharT, _Traits> _Istream;
__is.flags(_Istream::dec | _Istream::skipws);
result_type __mean;
result_type __stddev;
result_type _Vp = 0;
bool _V_hot = false;
__is >> __mean >> __stddev >> _V_hot;
if (_V_hot)
__is >> _Vp;
if (!__is.fail())
{
__x.param(param_type(__mean, __stddev));
__x._V_hot_ = _V_hot;
__x._V_ = _Vp;
}
return __is;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANDOM_NORMAL_DISTRIBUTION_H
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