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Sprout/sprout/math/cbrt.hpp
2016-02-25 18:48:28 +09:00

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2.5 KiB
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/*=============================================================================
Copyright (c) 2011-2016 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under 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 SPROUT_MATH_CBRT_HPP
#define SPROUT_MATH_CBRT_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/limits.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/math/constants.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/math/pow.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
inline SPROUT_CONSTEXPR float
builtin_cbrt(float x) {
return __builtin_cbrtf(x);
}
inline SPROUT_CONSTEXPR double
builtin_cbrt(double x) {
return __builtin_cbrt(x);
}
inline SPROUT_CONSTEXPR long double
builtin_cbrt(long double x) {
return __builtin_cbrtl(x);
}
#endif
template<typename T>
inline SPROUT_CONSTEXPR T
cbrt_impl(T x) {
return x < 0 ? -sprout::pow(-x, sprout::math::third<T>())
: sprout::pow(x, sprout::math::third<T>())
;
}
} // namespace detail
//
// cbrt
//
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
cbrt(FloatType x) {
return sprout::math::isnan(x) ? x
: x == sprout::numeric_limits<FloatType>::infinity() ? sprout::numeric_limits<FloatType>::infinity()
: x == -sprout::numeric_limits<FloatType>::infinity() ? -sprout::numeric_limits<FloatType>::infinity()
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
: sprout::math::detail::builtin_cbrt(x)
#else
: x == 0 ? x
: static_cast<FloatType>(sprout::math::detail::cbrt_impl(static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x)))
#endif
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
cbrt(IntType x) {
return sprout::math::cbrt(static_cast<double>(x));
}
} // namespace math
using sprout::math::cbrt;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_CBRT_HPP