public Matrix getL () {
      Matrix X = new Matrix(m,n);
      double[][] L = X.getArray();
      for (int i = 0; i < m; i++) {
         for (int j = 0; j < n; j++) {
            if (i > j) {
               L[i][j] = LU[i][j];
            } else if (i == j) {
               L[i][j] = 1.0;
            } else {
               L[i][j] = 0.0;
            }
         }
      }
      return X;
   }