public Point_3 computeCoordinates_3(int i, double[] eigenvalues, double[][] eigenvectors) {
   double x, y, z;
   x = eigenvectors[i][1] / Math.sqrt(eigenvalues[1]);
   y = eigenvectors[i][2] / Math.sqrt(eigenvalues[2]);
   z = eigenvectors[i][3] / Math.sqrt(eigenvalues[3]);
   return new Point_3(x, y, z);
 }
 public Point_2 computeCoordinates_2(int i, double[] eigenvalues, double[][] eigenvectors) {
   double x, y;
   x = eigenvectors[i][1] / Math.sqrt(eigenvalues[1]);
   y = eigenvectors[i][2] / Math.sqrt(eigenvalues[2]);
   return new Point_2(x, y);
 }