tanh_function.hpp

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#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_TANH_FUNCTION_HPP
#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_TANH_FUNCTION_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace ann  {

class TanhFunction
{
  public:
  static double fn(const double x)
  {
    return std::tanh(x);
  }

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

  static double deriv(const double y)
  {
    return 1 - std::pow(y, 2);
  }

  template<typename InputVecType, typename OutputVecType>
  static void deriv(const InputVecType& y, OutputVecType& x)
  {
    x = 1 - arma::pow(y, 2);
  }

  static double inv(const double y)
  {
    return std::atanh(y);
  }

  template<typename InputVecType, typename OutputVecType>
  static void inv(const InputVecType& y, OutputVecType& x)
  {
    x = arma::atanh(y);
  }
}; // class TanhFunction

} // namespace ann
} // namespace mlpack

#endif