Sprout/sprout/math/exp.hpp
2012-06-23 13:22:50 +09:00

58 lines
1.4 KiB
C++

#ifndef SPROUT_MATH_EXP_HPP
#define SPROUT_MATH_EXP_HPP
#include <cstddef>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/factorial.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
exp_impl(T x, T tmp, std::size_t n, T xn) {
return n > sprout::math::factorial_limit<T>() ? tmp
: sprout::math::detail::exp_impl(
x,
tmp + xn / sprout::math::factorial<T>(n),
n + 1,
xn * x
)
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
exp(FloatType x) {
typedef double type;
return static_cast<FloatType>(sprout::math::detail::exp_impl(
static_cast<type>(x),
type(1),
1,
static_cast<type>(x)
));
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
exp(IntType x) {
return sprout::math::detail::exp(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::exp;
} // namespace math
using sprout::math::exp;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_EXP_HPP