/usr/include/boost/math/special_functions
Edit: /usr/include/boost/math/special_functions/sign.hpp (5648B)
// (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
#include
#include
namespace boost{ namespace math{
namespace detail {
// signbit
#ifdef BOOST_MATH_USE_STD_FPCLASSIFY
template
inline int signbit_impl(T x, native_tag const&)
{
return (std::signbit)(x) ? 1 : 0;
}
#endif
// Generic versions first, note that these do not handle
// signed zero or NaN.
template
inline int signbit_impl(T x, generic_tag const&)
{
return x < 0;
}
template
inline int signbit_impl(T x, generic_tag const&)
{
return x < 0;
}
#if defined(__GNUC__) && (LDBL_MANT_DIG == 106)
//
// Special handling for GCC's "double double" type,
// in this case the sign is the same as the sign we
// get by casting to double, no overflow/underflow
// can occur since the exponents are the same magnitude
// for the two types:
//
inline int signbit_impl(long double x, generic_tag const&)
{
return (boost::math::signbit)(static_cast(x));
}
inline int signbit_impl(long double x, generic_tag const&)
{
return (boost::math::signbit)(static_cast(x));
}
#endif
template
inline int signbit_impl(T x, ieee_copy_all_bits_tag const&)
{
typedef BOOST_DEDUCED_TYPENAME fp_traits::type traits;
BOOST_DEDUCED_TYPENAME traits::bits a;
traits::get_bits(x,a);
return a & traits::sign ? 1 : 0;
}
template
inline int signbit_impl(T x, ieee_copy_leading_bits_tag const&)
{
typedef BOOST_DEDUCED_TYPENAME fp_traits::type traits;
BOOST_DEDUCED_TYPENAME traits::bits a;
traits::get_bits(x,a);
return a & traits::sign ? 1 : 0;
}
// Changesign
// Generic versions first, note that these do not handle
// signed zero or NaN.
template
inline T (changesign_impl)(T x, generic_tag const&)
{
return -x;
}
template
inline T (changesign_impl)(T x, generic_tag const&)
{
return -x;
}
#if defined(__GNUC__) && (LDBL_MANT_DIG == 106)
//
// Special handling for GCC's "double double" type,
// in this case we need to change the sign of both
// components of the "double double":
//
inline long double (changesign_impl)(long double x, generic_tag const&)
{
double* pd = reinterpret_cast(&x);
pd[0] = boost::math::changesign(pd[0]);
pd[1] = boost::math::changesign(pd[1]);
return x;
}
inline long double (changesign_impl)(long double x, generic_tag const&)
{
double* pd = reinterpret_cast(&x);
pd[0] = boost::math::changesign(pd[0]);
pd[1] = boost::math::changesign(pd[1]);
return x;
}
#endif
template
inline T changesign_impl(T x, ieee_copy_all_bits_tag const&)
{
typedef BOOST_DEDUCED_TYPENAME fp_traits::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
inline T (changesign_impl)(T x, ieee_copy_leading_bits_tag const&)
{
typedef BOOST_DEDUCED_TYPENAME fp_traits::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 int (signbit)(T x)
{
typedef typename detail::fp_traits::type traits;
typedef typename traits::method method;
// typedef typename boost::is_floating_point::type fp_tag;
typedef typename tools::promote_args_permissive::type result_type;
return detail::signbit_impl(static_cast(x), method());
}
template
inline int sign BOOST_NO_MACRO_EXPAND(const T& z)
{
return (z == 0) ? 0 : (boost::math::signbit)(z) ? -1 : 1;
}
template typename tools::promote_args_permissive::type (changesign)(const T& x)
{ //!< \brief return unchanged binary pattern of x, except for change of sign bit.
typedef typename detail::fp_traits::sign_change_type traits;
typedef typename traits::method method;
// typedef typename boost::is_floating_point::type fp_tag;
typedef typename tools::promote_args_permissive::type result_type;
return detail::changesign_impl(static_cast(x), method());
}
template
inline typename tools::promote_args_permissive::type
copysign BOOST_NO_MACRO_EXPAND(const T& x, const U& y)
{
BOOST_MATH_STD_USING
typedef typename tools::promote_args_permissive::type result_type;
return (boost::math::signbit)(static_cast(x)) != (boost::math::signbit)(static_cast(y))
? (boost::math::changesign)(static_cast(x)) : static_cast(x);
}
} // namespace math
} // namespace boost
#endif // BOOST_MATH_TOOLS_SIGN_HPP