Sprout/sprout/math/exp2.hpp
2013-05-05 00:06:30 +09:00

56 lines
1.7 KiB
C++

#ifndef SPROUT_MATH_EXP2_HPP
#define SPROUT_MATH_EXP2_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/math/constants.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/math/exp.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
exp2_impl(T x) {
return sprout::math::exp(x * sprout::math::ln_two<T>());
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
exp2(FloatType x) {
return sprout::math::isnan(x) ? x
: x == -std::numeric_limits<FloatType>::infinity() ? FloatType(0)
: x == std::numeric_limits<FloatType>::infinity() ? std::numeric_limits<FloatType>::infinity()
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
: std::exp2(x)
#else
: x == 0 ? FloatType(1)
: static_cast<FloatType>(sprout::math::detail::exp2_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
exp2(IntType x) {
return sprout::math::detail::exp2(static_cast<double>(x));
}
} // namespace detail
using sprout::math::detail::exp2;
} // namespace math
using sprout::math::exp2;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_EXP2_HPP