code: public Matrix getD () {
  		Matrix X = new Matrix(n,n);
  		double[][] D = X.getArray();
  		for (int i = 0; i < n; i++) {
  			for (int j = 0; j < n; j++) {
  				D[i][j] = 0.0;
  			}
  			D[i][i] = d[i];
  			if (e[i] > 0) {
  				D[i][i+1] = e[i];
  			} else if (e[i] < 0) {
  				D[i][i-1] = e[i];
  			}
  		}
  		return X;
  	}
docs: Return the block diagonal eigenvalue matrix
  @return     D