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-rw-r--r--boost/math/special_functions/sign.hpp145
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+// (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
+
+