rectifier_function.hpp

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#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_RECTIFIER_FUNCTION_HPP
#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_RECTIFIER_FUNCTION_HPP

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

namespace mlpack {
namespace ann  {

class RectifierFunction
{
 public:
  static double Fn(const double x)
  {
    return std::max(0.0, x);
  }

  template<typename eT>
  static void Fn(const arma::Mat<eT>& x, arma::Mat<eT>& y)
  {
    y.zeros(x.n_rows, x.n_cols);
    y = arma::max(y, x);
  }

  template<typename eT>
  static void Fn(const arma::Cube<eT>& x, arma::Cube<eT>& y)
  {
    y.zeros(x.n_rows, x.n_cols, x.n_slices);
    y = arma::max(y, x);
  }

  static double Deriv(const double x)
  {
    return (double)(x > 0);
  }

  template<typename InputType, typename OutputType>
  static void Deriv(const InputType& y, OutputType& x)
  {
    x.set_size(arma::size(y));

    for (size_t i = 0; i < y.n_elem; ++i)
      x(i) = Deriv(y(i));
  }
}; // class RectifierFunction

} // namespace ann
} // namespace mlpack

#endif