public String toString() {
		String str = "";
		for (int i = 0; i < dim; i++) {
			for (int j = 0; j < dim; j++) {
				if (i == j + 1)
					str += lower[j] + "\t";
				else if (i == j)
					str += diag[i] + "\t";
				else if (i == j - 1)
					str += upper[i] + "\t";
				else
					str += "-\t";
			}
			str += "\n";
		}
		return str;
	}