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Sprout/sprout/math/cbrt.hpp
2013-08-07 00:15:09 +09:00

59 lines
1.8 KiB
C++

#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 {
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>())
;
}
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
: std::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::detail::cbrt(static_cast<double>(x));
}
} // namespace detail
using sprout::math::detail::cbrt;
} // namespace math
using sprout::math::cbrt;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_CBRT_HPP