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author | Anas Nashif <anas.nashif@intel.com> | 2012-10-30 12:57:26 -0700 |
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committer | Anas Nashif <anas.nashif@intel.com> | 2012-10-30 12:57:26 -0700 |
commit | 1a78a62555be32868418fe52f8e330c9d0f95d5a (patch) | |
tree | d3765a80e7d3b9640ec2e930743630cd6b9fce2b /boost/math/special_functions/sign.hpp | |
download | boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.tar.gz boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.tar.bz2 boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.zip |
Imported Upstream version 1.49.0upstream/1.49.0
Diffstat (limited to 'boost/math/special_functions/sign.hpp')
-rw-r--r-- | boost/math/special_functions/sign.hpp | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/boost/math/special_functions/sign.hpp b/boost/math/special_functions/sign.hpp new file mode 100644 index 0000000000..6de88b29a2 --- /dev/null +++ b/boost/math/special_functions/sign.hpp @@ -0,0 +1,145 @@ +// (C) Copyright John Maddock 2006. +// (C) Copyright Johan Rade 2006. +// (C) Copyright Paul A. Bristow 2011 (added changesign). + +// Use, modification and distribution are subject to the +// Boost Software License, Version 1.0. (See accompanying file +// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) + +#ifndef BOOST_MATH_TOOLS_SIGN_HPP +#define BOOST_MATH_TOOLS_SIGN_HPP + +#ifdef _MSC_VER +#pragma once +#endif + +#include <boost/math/tools/config.hpp> +#include <boost/math/special_functions/math_fwd.hpp> +#include <boost/math/special_functions/detail/fp_traits.hpp> + +namespace boost{ namespace math{ + +namespace detail { + + // signbit + +#ifdef BOOST_MATH_USE_STD_FPCLASSIFY + template<class T> + inline int signbit_impl(T x, native_tag const&) + { + return (std::signbit)(x); + } +#endif + + template<class T> + inline int signbit_impl(T x, generic_tag<true> const&) + { + return x < 0; + } + + template<class T> + inline int signbit_impl(T x, generic_tag<false> const&) + { + return x < 0; + } + + template<class T> + inline int signbit_impl(T x, ieee_copy_all_bits_tag const&) + { + typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; + + BOOST_DEDUCED_TYPENAME traits::bits a; + traits::get_bits(x,a); + return a & traits::sign ? 1 : 0; + } + + template<class T> + inline int signbit_impl(T x, ieee_copy_leading_bits_tag const&) + { + typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; + + BOOST_DEDUCED_TYPENAME traits::bits a; + traits::get_bits(x,a); + + return a & traits::sign ? 1 : 0; + } + + // Changesign + + template<class T> + inline T (changesign_impl)(T x, generic_tag<true> const&) + { + return -x; + } + + template<class T> + inline T (changesign_impl)(T x, generic_tag<false> const&) + { + return -x; + } + + + template<class T> + inline T changesign_impl(T x, ieee_copy_all_bits_tag const&) + { + typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::sign_change_type traits; + + BOOST_DEDUCED_TYPENAME traits::bits a; + traits::get_bits(x,a); + a ^= traits::sign; + traits::set_bits(x,a); + return x; + } + + template<class T> + inline T (changesign_impl)(T x, ieee_copy_leading_bits_tag const&) + { + typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::sign_change_type traits; + + BOOST_DEDUCED_TYPENAME traits::bits a; + traits::get_bits(x,a); + a ^= traits::sign; + traits::set_bits(x,a); + return x; + } + + +} // namespace detail + +template<class T> int (signbit)(T x) +{ + typedef typename detail::fp_traits<T>::type traits; + typedef typename traits::method method; + typedef typename boost::is_floating_point<T>::type fp_tag; + return detail::signbit_impl(x, method()); +} + +template <class T> +inline int sign BOOST_NO_MACRO_EXPAND(const T& z) +{ + return (z == 0) ? 0 : (boost::math::signbit)(z) ? -1 : 1; +} + +template<class T> T (changesign)(const T& x) +{ //!< \brief return unchanged binary pattern of x, except for change of sign bit. + typedef typename detail::fp_traits<T>::sign_change_type traits; + typedef typename traits::method method; + typedef typename boost::is_floating_point<T>::type fp_tag; + + return detail::changesign_impl(x, method()); +} + +template <class T> +inline T copysign BOOST_NO_MACRO_EXPAND(const T& x, const T& y) +{ + BOOST_MATH_STD_USING + return (boost::math::signbit)(x) != (boost::math::signbit)(y) ? (boost::math::changesign)(x) : x; +} + +} // namespace math +} // namespace boost + + +#endif // BOOST_MATH_TOOLS_SIGN_HPP + + |