mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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84 lines
2.8 KiB
C++
84 lines
2.8 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/detail/pow.hpp>
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#include <sprout/math/detail/config.hpp>
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#include <sprout/math/detail/float_compute.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/fabs.hpp>
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#include <sprout/math/sqrt.hpp>
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#include <sprout/type_traits/enabler_if.hpp>
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#include <sprout/type_traits/float_promote.hpp>
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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_1(T x, std::size_t n, std::size_t last) {
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return last - n == 1
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? sprout::math::unchecked_factorial<T>(2 * n)
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/ sprout::detail::pow_n(T(4), n) / sprout::detail::pow2(sprout::math::unchecked_factorial<T>(n)) / (2 * n + 1)
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* sprout::detail::pow_n(x, 2 * n + 1)
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: sprout::math::detail::asin_impl_1(x, n, n + (last - n) / 2)
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+ sprout::math::detail::asin_impl_1(x, n + (last - n) / 2, last)
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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), 0, sprout::math::factorial_limit<T>() / 2 + 1)
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: x + sprout::math::detail::asin_impl_1(x, 1, sprout::math::factorial_limit<T>() / 2 + 1)
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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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return sprout::math::fabs(x) > 1 ? std::numeric_limits<FloatType>::quiet_NaN()
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#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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: std::asin(x)
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#else
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: x == 0 ? FloatType(0)
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: static_cast<FloatType>(
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x < 0 ? -sprout::math::detail::asin_impl(static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(-x))
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: sprout::math::detail::asin_impl(static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x))
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)
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#endif
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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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//
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// asin
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//
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template<
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typename ArithmeticType,
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typename sprout::enabler_if<std::is_arithmetic<ArithmeticType>::value>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType>::type
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asin(ArithmeticType x) {
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return sprout::math::detail::asin(x);
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}
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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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