Sprout/sprout/math/copysign.hpp
2013-04-29 10:56:46 +09:00

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#ifndef SPROUT_MATH_COPYSIGN_HPP
#define SPROUT_MATH_COPYSIGN_HPP
#include <limits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/math/signbit.hpp>
#include <sprout/type_traits/float_promote.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
copysign(FloatType x, FloatType y) {
return x == 0
? y == 0 ? y
: sprout::math::signbit(y) ? -FloatType(0)
: FloatType(0)
: sprout::math::isnan(x)
? sprout::math::isnan(y) ? y
: sprout::math::signbit(y) ? -std::numeric_limits<FloatType>::quiet_NaN()
: std::numeric_limits<FloatType>::quiet_NaN()
: sprout::math::signbit(y) != sprout::math::signbit(x) ? -x
: x
;
}
template<
typename ArithmeticType1,
typename ArithmeticType2,
typename sprout::enabler_if<
std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
copysign(ArithmeticType1 x, ArithmeticType2 y) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::detail::copysign(static_cast<type>(x), static_cast<type>(y));
}
} // namespace detail
//
// issue:
// [ !SPROUT_USE_BUILTIN_CMATH_FUNCTION ]
// copysign(<28>}x, -0) returns -x for |x| is not 0 .
// # returns +x . ( same as copysign(<28>}x, +0) )
// copysign(<28>}x, -NaN) returns -x for |x| is not NaN .
// # returns +x . ( same as copysign(<28>}x, +NaN) )
//
using NS_SPROUT_MATH_DETAIL::copysign;
} // namespace math
using sprout::math::copysign;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_COPYSIGN_HPP