spline_function.hpp

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#ifndef MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_SPLINE_FUNCTION_HPP
#define MLPACK_METHODS_ANN_ACTIVATION_FUNCTIONS_SPLINE_FUNCTION_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace ann  {

class SplineFunction
{
 public:
  static double Fn(const double x)
  {
    return std::pow(x, 2) * std::log(1 + x);
  }

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

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

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

} // namespace ann
} // namespace mlpack

#endif