Dear GAP Forum,
(I sent this message early in July, but I did not see it appear in the
GAP Forum, so apologies if it appears twice!)
I have an expression, z, say, involving the n-th roots of unity E(n), which evaluates to a real number (i.e. ComplexCojugate(z) = z.) For example z := E(5) + E(5)^-1 + E(3) + E(3)^-1;
Is there any way to test within GAP whether z is greater than 0, numerically?