hard_swish_function.hpp

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#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_HARD_SWISH_FUNCTION_HPP
#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_HARD_SWISH_FUNCTION_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace ann  {
class HardSwishFunction
{
 public:
  static double Fn(const double x)
  {
    if (x <= -3)
      return 0;
    else if (x >= 3)
      return x;

    return x * (x + 3) / 6;
  }

  template <typename InputVecType, typename OutputVecType>
  static void Fn(const InputVecType &x, OutputVecType &y)
  {
    y.set_size(size(x));

    for (size_t i = 0; i < x.n_elem; i++)
      y(i) = Fn(x(i));
  }

  static double Deriv(const double y)
  {
    if (y <= -3)
      return 0;
    else if (y >= 3)
      return 1;

    return (2 * y + 3.0) / 6.0;
  }

  template <typename InputVecType, typename OutputVecType>
  static void Deriv(const InputVecType &y, OutputVecType &x)
  {
    x.set_size(size(y));

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

} // namespace ann
} // namespace mlpack

#endif