elliot_function.hpp

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#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_ELLIOT_FUNCTION_HPP
#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_ELLIOT_FUNCTION_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace ann  {

class ElliotFunction
{
 public:
  static double Fn(const double x)
  {
    return x / (1.0 + std::abs(x));
  }

  template <typename InputVecType, typename OutputVecType>
  static void Fn(const InputVecType &x, OutputVecType &y)
  {
    y = x / (1.0 + arma::abs(x));
  }

  static double Deriv(const double y)
  {
    return 1.0 / std::pow(1.0 + std::abs(y), 2);
  }

  template <typename InputVecType, typename OutputVecType>
  static void Deriv(const InputVecType &y, OutputVecType &x)
  {
    x = 1.0 / arma::pow(1.0 + arma::abs(y), 2);
  }
}; // class ElliotFunction

} // namespace ann
} // namespace mlpack

#endif