mlpack 3.4.2
softsign_function.hpp
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1
25#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_SOFTSIGN_FUNCTION_HPP
26#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_SOFTSIGN_FUNCTION_HPP
27
28#include <mlpack/prereqs.hpp>
29
30namespace mlpack {
31namespace ann {
32
48{
49 public:
56 static double Fn(const double x)
57 {
58 if (x < DBL_MAX)
59 return x > -DBL_MAX ? x / (1.0 + std::abs(x)) : -1.0;
60 return 1.0;
61 }
62
69 template<typename InputVecType, typename OutputVecType>
70 static void Fn(const InputVecType& x, OutputVecType& y)
71 {
72 y.set_size(arma::size(x));
73
74 for (size_t i = 0; i < x.n_elem; ++i)
75 y(i) = Fn(x(i));
76 }
77
84 static double Deriv(const double y)
85 {
86 return std::pow(1.0 - std::abs(y), 2);
87 }
88
95 template<typename InputVecType, typename OutputVecType>
96 static void Deriv(const InputVecType& y, OutputVecType& x)
97 {
98 x = arma::pow(1.0 - arma::abs(y), 2);
99 }
100
107 static double Inv(const double y)
108 {
109 if (y > 0)
110 return y < 1 ? -y / (y - 1) : DBL_MAX;
111 else
112 return y > -1 ? y / (1 + y) : -DBL_MAX;
113 }
114
121 template<typename InputVecType, typename OutputVecType>
122 static void Inv(const InputVecType& y, OutputVecType& x)
123 {
124 x.set_size(arma::size(y));
125
126 for (size_t i = 0; i < y.n_elem; ++i)
127 x(i) = Inv(y(i));
128 }
129}; // class SoftsignFunction
130
131} // namespace ann
132} // namespace mlpack
133
134#endif
The softsign function, defined by.
static double Fn(const double x)
Computes the softsign function.
static double Deriv(const double y)
Computes the first derivative of the softsign function.
static double Inv(const double y)
Computes the inverse of the softsign function.
static void Deriv(const InputVecType &y, OutputVecType &x)
Computes the first derivatives of the softsign function.
static void Inv(const InputVecType &y, OutputVecType &x)
Computes the inverse of the softsign function.
static void Fn(const InputVecType &x, OutputVecType &y)
Computes the softsign function.
Linear algebra utility functions, generally performed on matrices or vectors.
Definition: cv.hpp:1
The core includes that mlpack expects; standard C++ includes and Armadillo.