code: public Matrix getU () {
  		Matrix X = new Matrix(n,n);
  		double[][] U = X.getArray();
  		for (int i = 0; i < n; i++) {
  			for (int j = 0; j < n; j++) {
  				if (i <= j) {
  					U[i][j] = LU[i][j];
  				} else {
  					U[i][j] = 0.0;
  				}
  			}
  		}
  		return X;
  	}
docs: Return upper triangular factor
  @return     U