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

62 lines
1.9 KiB
C++

#ifndef SPROUT_MATH_COSH_HPP
#define SPROUT_MATH_COSH_HPP
#include <cstddef>
#include <limits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/detail/pow.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.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
cosh_impl(T x2, std::size_t n, std::size_t last) {
return last - n == 1
? sprout::detail::pow_n(x2, n) / sprout::math::factorial<T>(2 * n)
: sprout::math::detail::cosh_impl(x2, n, n + (last - n) / 2)
+ sprout::math::detail::cosh_impl(x2, n + (last - n) / 2, last)
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
cosh(FloatType x) {
typedef typename sprout::math::detail::float_compute<FloatType>::type type;
return x == 0 ? FloatType(1)
: x == std::numeric_limits<FloatType>::infinity() || x == -std::numeric_limits<FloatType>::infinity()
? std::numeric_limits<FloatType>::infinity()
: static_cast<FloatType>(
type(1) + sprout::math::detail::cosh_impl(
static_cast<type>(x) * static_cast<type>(x),
1, sprout::math::factorial_limit<type>() / 2 + 1
)
)
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
cosh(IntType x) {
return sprout::math::detail::cosh(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::cosh;
} // namespace math
using sprout::math::cosh;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_COSH_HPP