151 lines
4.0 KiB
C++
151 lines
4.0 KiB
C++
// (C) Copyright John Maddock 2006.
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// (C) Copyright Johan Rade 2006.
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// (C) Copyright Paul A. Bristow 2011 (added changesign).
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_TOOLS_SIGN_HPP
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#define BOOST_MATH_TOOLS_SIGN_HPP
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#ifdef _MSC_VER
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#pragma once
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#endif
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#include <boost/math/tools/config.hpp>
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#include <boost/math/special_functions/math_fwd.hpp>
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#include <boost/math/special_functions/detail/fp_traits.hpp>
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namespace boost{ namespace math{
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namespace detail {
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// signbit
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#ifdef BOOST_MATH_USE_STD_FPCLASSIFY
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template<class T>
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inline int signbit_impl(T x, native_tag const&)
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{
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return (std::signbit)(x);
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}
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#endif
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template<class T>
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inline int signbit_impl(T x, generic_tag<true> const&)
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{
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return x < 0;
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}
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template<class T>
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inline int signbit_impl(T x, generic_tag<false> const&)
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{
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return x < 0;
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}
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template<class T>
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inline int signbit_impl(T x, ieee_copy_all_bits_tag const&)
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{
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typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits;
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BOOST_DEDUCED_TYPENAME traits::bits a;
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traits::get_bits(x,a);
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return a & traits::sign ? 1 : 0;
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}
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template<class T>
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inline int signbit_impl(T x, ieee_copy_leading_bits_tag const&)
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{
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typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits;
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BOOST_DEDUCED_TYPENAME traits::bits a;
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traits::get_bits(x,a);
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return a & traits::sign ? 1 : 0;
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}
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// Changesign
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template<class T>
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inline T (changesign_impl)(T x, generic_tag<true> const&)
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{
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return -x;
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}
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template<class T>
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inline T (changesign_impl)(T x, generic_tag<false> const&)
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{
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return -x;
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}
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template<class T>
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inline T changesign_impl(T x, ieee_copy_all_bits_tag const&)
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{
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typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::sign_change_type traits;
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BOOST_DEDUCED_TYPENAME traits::bits a;
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traits::get_bits(x,a);
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a ^= traits::sign;
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traits::set_bits(x,a);
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return x;
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}
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template<class T>
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inline T (changesign_impl)(T x, ieee_copy_leading_bits_tag const&)
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{
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typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::sign_change_type traits;
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BOOST_DEDUCED_TYPENAME traits::bits a;
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traits::get_bits(x,a);
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a ^= traits::sign;
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traits::set_bits(x,a);
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return x;
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}
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} // namespace detail
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template<class T> int (signbit)(T x)
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{
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typedef typename detail::fp_traits<T>::type traits;
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typedef typename traits::method method;
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// typedef typename boost::is_floating_point<T>::type fp_tag;
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typedef typename tools::promote_args<T>::type result_type;
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return detail::signbit_impl(static_cast<result_type>(x), method());
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}
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template <class T>
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inline int sign BOOST_NO_MACRO_EXPAND(const T& z)
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{
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return (z == 0) ? 0 : (boost::math::signbit)(z) ? -1 : 1;
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}
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template <class T> typename tools::promote_args<T>::type (changesign)(const T& x)
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{ //!< \brief return unchanged binary pattern of x, except for change of sign bit.
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typedef typename detail::fp_traits<T>::sign_change_type traits;
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typedef typename traits::method method;
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// typedef typename boost::is_floating_point<T>::type fp_tag;
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typedef typename tools::promote_args<T>::type result_type;
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return detail::changesign_impl(static_cast<result_type>(x), method());
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}
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template <class T, class U>
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inline typename tools::promote_args<T, U>::type
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copysign BOOST_NO_MACRO_EXPAND(const T& x, const U& y)
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{
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BOOST_MATH_STD_USING
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typedef typename tools::promote_args<T, U>::type result_type;
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return (boost::math::signbit)(static_cast<result_type>(x)) != (boost::math::signbit)(static_cast<result_type>(y))
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? (boost::math::changesign)(static_cast<result_type>(x)) : static_cast<result_type>(x);
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}
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} // namespace math
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} // namespace boost
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#endif // BOOST_MATH_TOOLS_SIGN_HPP
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