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?

Thanks,
Derek Holt.

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