mirror of
https://github.com/bolero-MURAKAMI/Sprout
synced 2024-11-12 21:09:01 +00:00
83 lines
2.2 KiB
C++
83 lines
2.2 KiB
C++
#ifndef SPROUT_MATH_ATAN_HPP
|
|
#define SPROUT_MATH_ATAN_HPP
|
|
|
|
#include <cstddef>
|
|
#include <type_traits>
|
|
#include <sprout/config.hpp>
|
|
#include <sprout/math/constants.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
|
|
atan_impl_2(T x, T tmp, std::size_t n, T x2n1) {
|
|
return n > sprout::math::factorial_limit<T>() ? tmp
|
|
: sprout::math::detail::atan_impl_2(
|
|
x,
|
|
tmp + (n % 2 ? -1 : 1) * x2n1 / (2 * n + 1),
|
|
n + 1,
|
|
x2n1 * x * x
|
|
)
|
|
;
|
|
}
|
|
template<typename T>
|
|
inline SPROUT_CONSTEXPR T
|
|
atan_impl_1(T x) {
|
|
return sprout::math::detail::atan_impl_2(
|
|
x,
|
|
x,
|
|
1,
|
|
x * x * x
|
|
);
|
|
}
|
|
template<typename T>
|
|
inline SPROUT_CONSTEXPR T
|
|
atan_impl(T x) {
|
|
return x > sprout::math::root_two<T>() + 1
|
|
? sprout::math::half_pi<T>() - sprout::math::detail::atan_impl_1(1 / x)
|
|
: x > sprout::math::root_two<T>() - 1
|
|
? sprout::math::quarter_pi<T>() + sprout::math::detail::atan_impl_1((x - 1) / (x + 1))
|
|
: sprout::math::detail::atan_impl_1(x)
|
|
;
|
|
}
|
|
|
|
template<
|
|
typename FloatType,
|
|
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
|
|
>
|
|
inline SPROUT_CONSTEXPR FloatType
|
|
atan(FloatType x) {
|
|
typedef double type;
|
|
return static_cast<FloatType>(
|
|
x < 0 ? -sprout::math::detail::atan_impl(static_cast<type>(-x))
|
|
: sprout::math::detail::atan_impl(static_cast<type>(x))
|
|
);
|
|
}
|
|
|
|
template<
|
|
typename IntType,
|
|
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
|
|
>
|
|
inline SPROUT_CONSTEXPR double
|
|
atan(IntType x) {
|
|
return sprout::math::detail::atan(static_cast<double>(x));
|
|
}
|
|
} // namespace detail
|
|
|
|
# if SPROUT_USE_BUILTIN_CMATH_FUNCTION
|
|
using std::atan;
|
|
# else
|
|
using sprout::math::detail::atan;
|
|
# endif
|
|
} // namespace math
|
|
|
|
using sprout::math::atan;
|
|
} // namespace sprout
|
|
|
|
#endif // #ifndef SPROUT_MATH_ATAN_HPP
|