mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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119 lines
4.3 KiB
C++
119 lines
4.3 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2013 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_MATH_POW_HPP
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#define SPROUT_MATH_POW_HPP
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/limits.hpp>
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#include <sprout/math/detail/config.hpp>
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#include <sprout/math/constants.hpp>
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#include <sprout/math/isnan.hpp>
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#include <sprout/math/copysign.hpp>
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#include <sprout/math/fabs.hpp>
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#include <sprout/math/exp.hpp>
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#include <sprout/math/log.hpp>
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#include <sprout/math/is_integer.hpp>
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#include <sprout/math/is_odd.hpp>
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#include <sprout/type_traits/float_promote.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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#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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inline SPROUT_CONSTEXPR float
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builtin_pow(float x, float y) {
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return __builtin_powf(x, y);
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}
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inline SPROUT_CONSTEXPR double
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builtin_pow(double x, double y) {
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return __builtin_pow(x, y);
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}
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inline SPROUT_CONSTEXPR long double
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builtin_pow(long double x, long double y) {
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return __builtin_powl(x, y);
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}
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#endif
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template<typename T>
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inline SPROUT_CONSTEXPR T
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pow_impl(T x, T y) {
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return sprout::math::exp(y * sprout::math::log(x));
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}
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} // namespace detail
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//
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// pow
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//
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// issue:
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// [ !SPROUT_USE_BUILTIN_CMATH_FUNCTION ]
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// pow(-0, y) returns -<2D>‡ for y an odd integer < 0.
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// # returns +<2B>‡ . ( same as pow(+0, y) )
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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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pow(FloatType x, FloatType y) {
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return x == 1 ? FloatType(1)
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: y == 0 ? FloatType(1)
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: sprout::math::isnan(y) ? y
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: sprout::math::isnan(x) ? x
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: x == 0
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? y < 0
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? sprout::math::is_odd(y) ? sprout::math::copysign(sprout::numeric_limits<FloatType>::infinity(), x)
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: sprout::numeric_limits<FloatType>::infinity()
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: sprout::math::is_odd(y) ? x
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: FloatType(0)
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: x == -1 && (y == sprout::numeric_limits<FloatType>::infinity() || y == -sprout::numeric_limits<FloatType>::infinity()) ? FloatType(1)
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: y == -sprout::numeric_limits<FloatType>::infinity()
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? sprout::math::fabs(x) < 1 ? sprout::numeric_limits<FloatType>::infinity()
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: FloatType(0)
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: y == sprout::numeric_limits<FloatType>::infinity()
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? sprout::math::fabs(x) < 1 ? FloatType(0)
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: sprout::numeric_limits<FloatType>::infinity()
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: x == -sprout::numeric_limits<FloatType>::infinity()
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? y < 0
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? sprout::math::is_odd(y) ? -FloatType(0)
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: FloatType(0)
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: sprout::math::is_odd(y) ? -sprout::numeric_limits<FloatType>::infinity()
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: sprout::numeric_limits<FloatType>::infinity()
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: x == sprout::numeric_limits<FloatType>::infinity()
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? y < 0 ? FloatType(0)
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: sprout::numeric_limits<FloatType>::infinity()
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: x < 0 && !sprout::math::is_integer(y) ? sprout::numeric_limits<FloatType>::quiet_NaN()
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#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
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: sprout::math::detail::builtin_pow(x, y)
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#else
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: static_cast<FloatType>(sprout::math::detail::pow_impl(
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static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x),
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static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(y)
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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 ArithmeticType1,
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typename ArithmeticType2,
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typename sprout::enabler_if<
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std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
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>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
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pow(ArithmeticType1 x, ArithmeticType2 y) {
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typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
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return sprout::math::pow(static_cast<type>(x), static_cast<type>(y));
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}
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} // namespace math
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using sprout::math::pow;
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} // namespace sprout
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#endif // #ifndef SPROUT_MATH_POW_HPP
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