@Christian Wolinski Why we need to put 'map' and 'identity' in 'Sols'? Secondly, how can I extract 'c, mu, a[-1], a[0], a[1], b[-1], b[0], b[1]' from 'Sols'? By writing 'Sol1 := op(11, op(7, Sols));
Sol2 := op(15, op(7, Sols));' in the worksheet, I found an error.