mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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88 lines
2.4 KiB
C++
88 lines
2.4 KiB
C++
#ifndef SPROUT_MATH_ASIN_HPP
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#define SPROUT_MATH_ASIN_HPP
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#include <cstddef>
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#include <limits>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/math/constants.hpp>
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#include <sprout/math/factorial.hpp>
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#include <sprout/math/sqrt.hpp>
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#include <sprout/utility/enabler_if.hpp>
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#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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# include <cmath>
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#endif
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namespace sprout {
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namespace math {
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namespace detail {
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template<typename T>
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inline SPROUT_CONSTEXPR T
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asin_impl_2(T x, T tmp, std::size_t n, T x2n1, T _4n) {
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return 2 * n > sprout::math::factorial_limit<T>() ? tmp
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: sprout::math::detail::asin_impl_2(
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x,
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tmp + sprout::math::factorial<T>(2 * n)
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/ _4n / sprout::math::factorial<T>(n) / sprout::math::factorial<T>(n) / (2 * n + 1)
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* x2n1
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,
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n + 1,
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x2n1 * x * x,
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_4n * 4
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)
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;
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}
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template<typename T>
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inline SPROUT_CONSTEXPR T
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asin_impl_1(T x) {
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return sprout::math::detail::asin_impl_2(
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x,
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x,
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1,
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x * x * x,
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T(4)
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);
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}
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template<typename T>
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inline SPROUT_CONSTEXPR T
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asin_impl(T x) {
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return x > sprout::math::half_root_two<T>()
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? sprout::math::half_pi<T>() - sprout::math::detail::asin_impl_1(sprout::math::sqrt(1 - x * x))
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: sprout::math::detail::asin_impl_1(x)
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;
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}
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template<
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typename FloatType,
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typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR FloatType
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asin(FloatType x) {
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typedef double type;
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return x > 1 || x < -1 ? std::numeric_limits<FloatType>::quiet_NaN()
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: x < 0 ? -static_cast<FloatType>(sprout::math::detail::asin_impl(static_cast<type>(-x)))
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: static_cast<FloatType>(sprout::math::detail::asin_impl(static_cast<type>(x)))
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;
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}
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template<
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typename IntType,
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typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR double
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asin(IntType x) {
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return sprout::math::detail::asin(static_cast<double>(x));
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}
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} // namespace detail
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# if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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using std::asin;
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# else
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using sprout::math::detail::asin;
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# endif
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} // namespace math
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using sprout::math::asin;
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} // namespace sprout
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#endif // #ifndef SPROUT_MATH_ASIN_HPP
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