lisht_function.hpp

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#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_LISHT_FUNCTION_HPP
#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_LISHT_FUNCTION_HPP

#include <mlpack/prereqs.hpp>
#include <algorithm>

namespace mlpack {
namespace ann  {

class LiSHTFunction
{
 public:
  static double Fn(const double x)
  {
    return x * std::tanh(x);
  }

  template <typename InputVecType, typename OutputVecType>
  static void Fn(const InputVecType &x, OutputVecType &y)
  {
    y = x % arma::tanh(x);
  }

  static double Deriv(const double y)
  {
    return std::tanh(y) + y * (1 - std::pow(std::tanh(y), 2));
  }

  template <typename InputVecType, typename OutputVecType>
  static void Deriv(const InputVecType &y, OutputVecType &x)
  {
    x = arma::tanh(y) + y % (1 - arma::pow(arma::tanh(y), 2));
  }
}; // class LishtFunction

} // namespace ann
} // namespace mlpack

#endif