private String[] makeSysEqn(int dim, TfDialog tf) {
		String[] xf = new String[dim];
		for (int i = 0; i < dim - 1; i++)
			xf[i] = "x" + (i + 2);
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < dim; i++) {
			sb.append("-(" + tf.getA(i) + ")*x" + (i + 1));
			if (i == dim - 1)
				sb.append("+");
		}
		sb.append("u1");
		xf[dim - 1] = sb.toString();
		return xf;
	}