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Sprout/sprout/math/cosh.hpp
2012-05-04 16:40:25 +09:00

64 lines
1.6 KiB
C++

#ifndef SPROUT_MATH_COSH_HPP
#define SPROUT_MATH_COSH_HPP
#include <cstddef>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/factorial.hpp>
#include <sprout/utility/enabler_if.hpp>
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
# include <cmath>
#endif
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
cosh_impl(T x, T tmp, std::size_t n, T x2n) {
return 2 * n > sprout::math::factorial_limit<T>() ? tmp
: sprout::math::detail::cosh_impl(
x,
tmp + x2n / sprout::math::factorial<T>(2 * n),
n + 1,
x2n * x * x
)
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
cosh(FloatType x) {
typedef double type;
return static_cast<FloatType>(sprout::math::detail::cosh_impl(
static_cast<type>(x),
type(1),
1,
static_cast<type>(x) * static_cast<type>(x)
));
}
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
# if SPROUT_USE_BUILTIN_CMATH_FUNCTION
using std::cosh;
# else
using sprout::math::detail::cosh;
# endif
} // namespace math
using sprout::math::cosh;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_COSH_HPP