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Upgrade to 2022-era LLVM LIBCXX
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Justine Tunney
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2f4ca71f26
commit
8e68384e15
2078 changed files with 165657 additions and 65010 deletions
216
third_party/libcxx/__random/gamma_distribution.h
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third_party/libcxx/__random/gamma_distribution.h
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//===----------------------------------------------------------------------===//
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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_GAMMA_DISTRIBUTION_H
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#define _LIBCPP___RANDOM_GAMMA_DISTRIBUTION_H
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#include <__config>
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#include <__random/exponential_distribution.h>
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#include <__random/is_valid.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 gamma_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 __alpha_;
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result_type __beta_;
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public:
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typedef gamma_distribution distribution_type;
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_LIBCPP_INLINE_VISIBILITY
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explicit param_type(result_type __alpha = 1, result_type __beta = 1)
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: __alpha_(__alpha), __beta_(__beta) {}
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_LIBCPP_INLINE_VISIBILITY
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result_type alpha() const {return __alpha_;}
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_LIBCPP_INLINE_VISIBILITY
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result_type beta() const {return __beta_;}
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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.__alpha_ == __y.__alpha_ && __x.__beta_ == __y.__beta_;}
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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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gamma_distribution() : gamma_distribution(1) {}
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_LIBCPP_INLINE_VISIBILITY
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explicit gamma_distribution(result_type __alpha, result_type __beta = 1)
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: __p_(param_type(__alpha, __beta)) {}
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#else
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_LIBCPP_INLINE_VISIBILITY
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explicit gamma_distribution(result_type __alpha = 1,
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result_type __beta = 1)
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: __p_(param_type(__alpha, __beta)) {}
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#endif
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_LIBCPP_INLINE_VISIBILITY
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explicit gamma_distribution(const param_type& __p)
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: __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>
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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_INLINE_VISIBILITY
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result_type alpha() const {return __p_.alpha();}
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_LIBCPP_INLINE_VISIBILITY
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result_type beta() const {return __p_.beta();}
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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 gamma_distribution& __x,
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const gamma_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 gamma_distribution& __x,
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const gamma_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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gamma_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p)
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{
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static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
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result_type __a = __p.alpha();
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uniform_real_distribution<result_type> __gen(0, 1);
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exponential_distribution<result_type> __egen;
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result_type __x;
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if (__a == 1)
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__x = __egen(__g);
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else if (__a > 1)
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{
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const result_type __b = __a - 1;
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const result_type __c = 3 * __a - result_type(0.75);
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while (true)
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{
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const result_type __u = __gen(__g);
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const result_type __v = __gen(__g);
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const result_type __w = __u * (1 - __u);
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if (__w != 0)
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{
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const result_type __y = _VSTD::sqrt(__c / __w) *
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(__u - result_type(0.5));
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__x = __b + __y;
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if (__x >= 0)
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{
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const result_type __z = 64 * __w * __w * __w * __v * __v;
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if (__z <= 1 - 2 * __y * __y / __x)
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break;
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if (_VSTD::log(__z) <= 2 * (__b * _VSTD::log(__x / __b) - __y))
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break;
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}
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}
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}
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}
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else // __a < 1
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{
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while (true)
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{
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const result_type __u = __gen(__g);
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const result_type __es = __egen(__g);
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if (__u <= 1 - __a)
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{
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__x = _VSTD::pow(__u, 1 / __a);
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if (__x <= __es)
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break;
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}
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else
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{
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const result_type __e = -_VSTD::log((1-__u)/__a);
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__x = _VSTD::pow(1 - __a + __a * __e, 1 / __a);
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if (__x <= __e + __es)
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break;
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}
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}
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}
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return __x * __p.beta();
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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,
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const gamma_distribution<_RT>& __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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_CharT __sp = __os.widen(' ');
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__os.fill(__sp);
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__os << __x.alpha() << __sp << __x.beta();
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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,
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gamma_distribution<_RT>& __x)
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{
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typedef gamma_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 __alpha;
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result_type __beta;
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__is >> __alpha >> __beta;
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if (!__is.fail())
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__x.param(param_type(__alpha, __beta));
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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_GAMMA_DISTRIBUTION_H
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