filter.hpp

#ifndef CONV_FILTER_H
#define CONV_FILTER_H

#include <cmath>

// allocate memory for a tensor
double ***get_tensor(int x, int y, int z) {
  double ***ret = new double**[x];
  for (int i = 0; i < x; i++) {
    ret[i] = new double* [y];
    for (int j = 0; j < y; ++j) {
      ret[i][j] = new double[z];
    }
  }
  return ret;
}

class filter {
public:
  double ***w, b;     // krenel matrix, bias term
  int window, depth;
  filter(int _window, int _depth) 
    : window(_window), depth(_depth) {
    w = get_tensor(window, window, depth); 
  }
  filter(double ***_w, int _window, int _depth, int _b = 0) 
    : window(_window), depth(_depth), b(_b) {
      w = get_tensor(window, window, depth); 
      for (int i = 0; i < window; ++i) {
        for (int j = 0; j < window; ++j) {
          for (int k = 0; k < depth; ++k) {
            w[i][j][k] = _w[i][j][k];
          }
        }
      }
  }
  ~filter() {
    for (int i = 0; i < window; ++i) {
      for (int j = 0; j < window; ++j) {
        delete[] w[i][j];
      }
      delete[] w[i];
    }
    delete[] w;
  }

  // normalize the tensor
  void normalize() {
    double sum = 0;
    for (int i = 0; i < window; ++i) {
      for (int j = 0; j < window; ++j) {
        for (int k = 0; k < depth; ++k) {
          sum += std::abs(w[i][j][k]);
        }
      }
    }

    for (int i = 0; i < window; ++i) {
      for (int j = 0; j < window; ++j) {
        for (int k = 0; k < depth; ++k) {
          w[i][j][k] /= sum;
        }
      }
    }
  }
};

#endif