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Sprout/sprout/math/cos.hpp
2012-12-03 21:48:50 +09:00

73 lines
2 KiB
C++

#ifndef SPROUT_MATH_COS_HPP
#define SPROUT_MATH_COS_HPP
#include <cstddef>
#include <limits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/factorial.hpp>
#include <sprout/math/constants.hpp>
#include <sprout/math/fmod.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
cos_impl_1(T x, T tmp, std::size_t n, T x2n) {
return 2 * n > sprout::math::factorial_limit<T>() ? tmp
: sprout::math::detail::cos_impl_1(
x,
tmp + (n % 2 ? -1 : 1) * x2n / sprout::math::factorial<T>(2 * n),
n + 1,
x2n * x * x
)
;
}
template<typename FloatType>
inline SPROUT_CONSTEXPR FloatType
cos_impl(FloatType x) {
typedef double type;
return static_cast<FloatType>(sprout::math::detail::cos_impl_1(
static_cast<type>(x),
type(1),
1,
static_cast<type>(x) * static_cast<type>(x)
))
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
cos(FloatType x) {
typedef double type;
return x == std::numeric_limits<FloatType>::infinity()
|| x == -std::numeric_limits<FloatType>::infinity()
? std::numeric_limits<FloatType>::quiet_NaN()
: sprout::math::detail::cos_impl(sprout::math::fmod(x, 2 * sprout::math::pi<FloatType>()))
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
cos(IntType x) {
return sprout::math::detail::cos(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::cos;
} // namespace math
using sprout::math::cos;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_COS_HPP