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145 lines
3.5 KiB
145 lines
3.5 KiB
// (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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return detail::signbit_impl(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> T (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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return detail::changesign_impl(x, method()); |
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} |
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template <class T> |
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inline T copysign BOOST_NO_MACRO_EXPAND(const T& x, const T& y) |
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{ |
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BOOST_MATH_STD_USING |
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return (boost::math::signbit)(x) != (boost::math::signbit)(y) ? (boost::math::changesign)(x) : 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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