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Sprout/sprout/math/sqrt.hpp
2013-02-14 18:02:43 +09:00

57 lines
1.8 KiB
C++

#ifndef SPROUT_MATH_SQRT_HPP
#define SPROUT_MATH_SQRT_HPP
#include <limits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
sqrt_impl_1(T x, T s, T s2) {
return !(s < s2) ? s2
: sprout::math::detail::sqrt_impl_1(x, (x / s + s) / 2, s)
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
sqrt_impl(T x, T s) {
return sprout::math::detail::sqrt_impl_1(x, (x / s + s) / 2, s);
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
sqrt(FloatType x) {
typedef typename sprout::math::detail::float_compute<FloatType>::type type;
return x == 0 ? FloatType(0)
: x == std::numeric_limits<FloatType>::infinity() ? std::numeric_limits<FloatType>::infinity()
: x == std::numeric_limits<FloatType>::quiet_NaN() ? std::numeric_limits<FloatType>::quiet_NaN()
: x < 0 ? std::numeric_limits<FloatType>::quiet_NaN()
: static_cast<FloatType>(sprout::math::detail::sqrt_impl(static_cast<type>(x), x > 1 ? static_cast<type>(x) : type(1)));
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
sqrt(IntType x) {
return sprout::math::detail::sqrt(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::sqrt;
} // namespace math
using sprout::math::sqrt;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_SQRT_HPP