orthogonal_init.hpp

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#ifndef MLPACK_METHODS_ANN_INIT_RULES_ORTHOGONAL_INIT_HPP
#define MLPACK_METHODS_ANN_INIT_RULES_ORTHOGONAL_INIT_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace ann  {

class OrthogonalInitialization
{
 public:
  OrthogonalInitialization(const double gain = 1.0) : gain(gain) { }

  template<typename eT>
  void Initialize(arma::Mat<eT>& W, const size_t rows, const size_t cols)
  {
    arma::Mat<eT> V;
    arma::Col<eT> s;

    arma::svd_econ(W, s, V, arma::randu<arma::Mat<eT> >(rows, cols));
    W *= gain;
  }

  template<typename eT>
  void Initialize(arma::Mat<eT>& W)
  {
    arma::Mat<eT> V;
    arma::Col<eT> s;

    arma::svd_econ(W, s, V, arma::randu<arma::Mat<eT> >(W.n_rows, W.n_cols));
    W *= gain;
  }

  template<typename eT>
  void Initialize(arma::Cube<eT>& W,
                  const size_t rows,
                  const size_t cols,
                  const size_t slices)
  {
    if (W.is_empty())
      W.set_size(rows, cols, slices);

    for (size_t i = 0; i < slices; ++i)
      Initialize(W.slice(i), rows, cols);
  }

  template<typename eT>
  void Initialize(arma::Cube<eT>& W)
  {
    if (W.is_empty())
      Log::Fatal << "Cannot initialize an empty cube." << std::endl;

    for (size_t i = 0; i < W.n_slices; ++i)
      Initialize(W.slice(i));
  }

 private:
  double gain;
}; // class OrthogonalInitialization


} // namespace ann
} // namespace mlpack

#endif