forked from OSchip/llvm-project
156 lines
4.8 KiB
C++
156 lines
4.8 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_EXPONENTIAL_DISTRIBUTION_H
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#define _LIBCPP___RANDOM_EXPONENTIAL_DISTRIBUTION_H
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#include <__config>
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#include <__random/generate_canonical.h>
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#include <__random/uniform_real_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 exponential_distribution
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{
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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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{
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result_type __lambda_;
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public:
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typedef exponential_distribution distribution_type;
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_LIBCPP_INLINE_VISIBILITY
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explicit param_type(result_type __lambda = 1) : __lambda_(__lambda) {}
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_LIBCPP_INLINE_VISIBILITY
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result_type lambda() const {return __lambda_;}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator==(const param_type& __x, const param_type& __y)
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{return __x.__lambda_ == __y.__lambda_;}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator!=(const param_type& __x, const param_type& __y)
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{return !(__x == __y);}
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};
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private:
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param_type __p_;
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public:
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// constructors and reset functions
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_INLINE_VISIBILITY
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exponential_distribution() : exponential_distribution(1) {}
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_LIBCPP_INLINE_VISIBILITY
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explicit exponential_distribution(result_type __lambda)
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: __p_(param_type(__lambda)) {}
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#else
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_LIBCPP_INLINE_VISIBILITY
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explicit exponential_distribution(result_type __lambda = 1)
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: __p_(param_type(__lambda)) {}
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#endif
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_LIBCPP_INLINE_VISIBILITY
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explicit exponential_distribution(const param_type& __p) : __p_(__p) {}
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_LIBCPP_INLINE_VISIBILITY
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void reset() {}
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// generating functions
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template<class _URNG>
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_LIBCPP_INLINE_VISIBILITY
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result_type operator()(_URNG& __g)
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{return (*this)(__g, __p_);}
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template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
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// property functions
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_LIBCPP_INLINE_VISIBILITY
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result_type lambda() const {return __p_.lambda();}
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_LIBCPP_INLINE_VISIBILITY
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param_type param() const {return __p_;}
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_LIBCPP_INLINE_VISIBILITY
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void param(const param_type& __p) {__p_ = __p;}
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_LIBCPP_INLINE_VISIBILITY
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result_type min() const {return 0;}
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_LIBCPP_INLINE_VISIBILITY
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result_type max() const {return numeric_limits<result_type>::infinity();}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator==(const exponential_distribution& __x,
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const exponential_distribution& __y)
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{return __x.__p_ == __y.__p_;}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator!=(const exponential_distribution& __x,
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const exponential_distribution& __y)
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{return !(__x == __y);}
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};
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template <class _RealType>
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template<class _URNG>
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_RealType
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exponential_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
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{
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return -_VSTD::log
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(
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result_type(1) -
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_VSTD::generate_canonical<result_type,
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numeric_limits<result_type>::digits>(__g)
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)
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/ __p.lambda();
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}
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template <class _CharT, class _Traits, class _RealType>
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const exponential_distribution<_RealType>& __x)
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{
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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 |
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_OStream::scientific);
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return __os << __x.lambda();
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}
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template <class _CharT, class _Traits, class _RealType>
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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exponential_distribution<_RealType>& __x)
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{
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typedef exponential_distribution<_RealType> _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 __lambda;
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__is >> __lambda;
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if (!__is.fail())
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__x.param(param_type(__lambda));
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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_EXPONENTIAL_DISTRIBUTION_H
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