mirror of
https://github.com/bolero-MURAKAMI/Sprout
synced 2024-11-12 21:09:01 +00:00
58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
#ifndef SPROUT_MATH_EXP_HPP
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#define SPROUT_MATH_EXP_HPP
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#include <cstddef>
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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/factorial.hpp>
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#include <sprout/type_traits/enabler_if.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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exp_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::detail::pow_n(x, n) / sprout::math::factorial<T>(n)
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: sprout::math::detail::exp_impl_1(x, n, n + (last - n) / 2)
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+ sprout::math::detail::exp_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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exp_impl(T x) {
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return 1 + sprout::math::detail::exp_impl_1(x, 1, sprout::math::factorial_limit<T>() + 1);
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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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exp(FloatType x) {
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typedef double type;
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return !(x > -1) ? 1 / sprout::math::detail::exp_impl(-static_cast<type>(x))
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: sprout::math::detail::exp_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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exp(IntType x) {
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return sprout::math::detail::exp(static_cast<double>(x));
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}
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} // namespace detail
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using NS_SPROUT_MATH_DETAIL::exp;
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} // namespace math
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using sprout::math::exp;
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} // namespace sprout
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#endif // #ifndef SPROUT_MATH_EXP_HPP
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