// (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)
namespace detail {
+ // signbit
+
#ifdef BOOST_MATH_USE_STD_FPCLASSIFY
template<class T>
inline int signbit_impl(T x, native_tag const&)
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)
-{ //!< \brief return true if floating-point type t is NaN (Not A Number).
+{
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());
+ // typedef typename boost::is_floating_point<T>::type fp_tag;
+ typedef typename tools::promote_args_permissive<T>::type result_type;
+ return detail::signbit_impl(static_cast<result_type>(x), method());
}
template <class T>
return (z == 0) ? 0 : (boost::math::signbit)(z) ? -1 : 1;
}
-template <class T>
-inline T copysign BOOST_NO_MACRO_EXPAND(const T& x, const T& y)
+template <class T> typename tools::promote_args_permissive<T>::type (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;
+ typedef typename tools::promote_args_permissive<T>::type result_type;
+
+ return detail::changesign_impl(static_cast<result_type>(x), method());
+}
+
+template <class T, class U>
+inline typename tools::promote_args_permissive<T, U>::type
+ copysign BOOST_NO_MACRO_EXPAND(const T& x, const U& y)
{
BOOST_MATH_STD_USING
- return fabs(x) * ((boost::math::signbit)(y) ? -1 : 1);
+ typedef typename tools::promote_args_permissive<T, U>::type result_type;
+ return (boost::math::signbit)(static_cast<result_type>(x)) != (boost::math::signbit)(static_cast<result_type>(y))
+ ? (boost::math::changesign)(static_cast<result_type>(x)) : static_cast<result_type>(x);
}
} // namespace math