elish_function.hpp
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1 
26 #ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_ELISH_FUNCTION_HPP
27 #define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_ELISH_FUNCTION_HPP
28 
29 #include <mlpack/prereqs.hpp>
30 
31 namespace mlpack {
32 namespace ann {
33 
49 {
50  public:
57  static double Fn(const double x)
58  {
59  if (x < 0.0)
60  return (std::exp(x) - 1) / (1 + std::exp(-x));
61 
62  return x / (1 + std::exp(-x));
63  }
64 
71  template<typename InputVecType, typename OutputVecType>
72  static void Fn(const InputVecType& x, OutputVecType& y)
73  {
74  y = ((x < 0.0) % ((arma::exp(x) -1) / (1 + arma::exp(-x))))
75  + ((x >= 0.0) % (x / (1 + arma::exp(-x))));
76  }
77 
84  static double Deriv(const double y)
85  {
86  if (y < 0.0)
87  {
88  return std::exp(y) - 2 / (1 + std::exp(y)) +
89  2 / std::pow(1 + std::exp(y) , 2);
90  }
91 
92  return 1 / (1 + std::exp(-y)) + y * std::exp(-y) /
93  std::pow(1 + std::exp(-y) , 2);
94  }
95 
102  template<typename InputVecType, typename OutputVecType>
103  static void Deriv(const InputVecType& y, OutputVecType& x)
104  {
105  x = ((y < 0.0) % (arma::exp(y) - 2 / (1 + arma::exp(y)) + 2 / arma::pow(
106  1 + arma::exp(y), 2))) + ((y >= 0.0) % (1 / (1 + arma::exp(-y)) + y %
107  arma::exp(-y) / arma::pow(1 + arma::exp(-y), 2)));
108  }
109 }; // class ElishFunction
110 
111 } // namespace ann
112 } // namespace mlpack
113 
114 #endif
static double Fn(const double x)
Computes the ELiSH function.
Linear algebra utility functions, generally performed on matrices or vectors.
static void Deriv(const InputVecType &y, OutputVecType &x)
Computes the first derivatives of the ELiSH function.
The core includes that mlpack expects; standard C++ includes, Armadillo, cereal, and a few basic mlpa...
The ELiSH function, defined by.
static double Deriv(const double y)
Computes the first derivatives of ELiSH function.
static void Fn(const InputVecType &x, OutputVecType &y)
Computes the ELiSH function.