Sprout/sprout/math/sigmoid.hpp

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/*=============================================================================
Copyright (c) 2011-2019 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_MATH_SIGMOID_HPP
#define SPROUT_MATH_SIGMOID_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/math/exp.hpp>
#include <sprout/type_traits/float_promote.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
//
// sigmoid
//
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
sigmoid_impl(T x){
return 1 / (1 + sprout::math::exp(-x));
}
template<typename T>
inline SPROUT_CONSTEXPR T
sigmoid_impl(T x, T a){
return sprout::math::detail::sigmoid_impl(a * x);
}
} // namespace detail
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
sigmoid(FloatType x){
return sprout::math::detail::sigmoid_impl(sprout::math::detail::as_float_compute(x));
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
sigmoid(FloatType x, FloatType a){
return sprout::math::detail::sigmoid_impl(sprout::math::detail::as_float_compute(x), sprout::math::detail::as_float_compute(a));
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
sigmoid(IntType x) {
return sprout::math::sigmoid(static_cast<double>(x));
}
template<
typename ArithmeticType1,
typename ArithmeticType2,
typename sprout::enabler_if<
std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
sigmoid(ArithmeticType1 x, ArithmeticType2 a) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::sigmoid(static_cast<type>(x), static_cast<type>(a));
}
//
// d_sigmoid
//
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
d_sigmoid_impl_1(T s){
return s * (1 - s);
}
template<typename T>
inline SPROUT_CONSTEXPR T
d_sigmoid_impl_1(T s, T a){
return a * s * (1 - s);
}
template<typename T>
inline SPROUT_CONSTEXPR T
d_sigmoid_impl(T x){
return sprout::math::detail::d_sigmoid_impl_1(sprout::math::sigmoid(x));
}
template<typename T>
inline SPROUT_CONSTEXPR T
d_sigmoid_impl(T x, T a){
return sprout::math::detail::d_sigmoid_impl_1(sprout::math::sigmoid(x, a), a);
}
} // namespace detail
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
d_sigmoid(FloatType x){
return sprout::math::detail::d_sigmoid_impl(sprout::math::detail::as_float_compute(x));
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
d_sigmoid(FloatType x, FloatType a){
return sprout::math::detail::d_sigmoid_impl(sprout::math::detail::as_float_compute(x), sprout::math::detail::as_float_compute(a));
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
d_sigmoid(IntType x) {
return sprout::math::d_sigmoid(static_cast<double>(x));
}
template<
typename ArithmeticType1,
typename ArithmeticType2,
typename sprout::enabler_if<
std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
d_sigmoid(ArithmeticType1 x, ArithmeticType2 a) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::d_sigmoid(static_cast<type>(x), static_cast<type>(a));
}
//
// d2_sigmoid
//
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
d2_sigmoid_impl_1(T s){
return s * (1 - s) * (1 - 2 * s);
}
template<typename T>
inline SPROUT_CONSTEXPR T
d2_sigmoid_impl_1(T s, T a){
return a * a * s * (1 - s) * (1 - 2 * s);
}
template<typename T>
inline SPROUT_CONSTEXPR T
d2_sigmoid_impl(T x){
return sprout::math::detail::d2_sigmoid_impl_1(sprout::math::sigmoid(x));
}
template<typename T>
inline SPROUT_CONSTEXPR T
d2_sigmoid_impl(T x, T a){
return sprout::math::detail::d2_sigmoid_impl_1(sprout::math::sigmoid(x, a), a);
}
} // namespace detail
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
d2_sigmoid(FloatType x){
return sprout::math::detail::d2_sigmoid_impl(sprout::math::detail::as_float_compute(x));
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
d2_sigmoid(FloatType x, FloatType a){
return sprout::math::detail::d2_sigmoid_impl(sprout::math::detail::as_float_compute(x), sprout::math::detail::as_float_compute(a));
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
d2_sigmoid(IntType x) {
return sprout::math::d2_sigmoid(static_cast<double>(x));
}
template<
typename ArithmeticType1,
typename ArithmeticType2,
typename sprout::enabler_if<
std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
d2_sigmoid(ArithmeticType1 x, ArithmeticType2 a) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::d2_sigmoid(static_cast<type>(x), static_cast<type>(a));
}
} // namespace math
using sprout::math::sigmoid;
using sprout::math::d_sigmoid;
using sprout::math::d2_sigmoid;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_SIGMOID_HPP