proposition: Lemma Creal_ReP z : reflect ('Re z = z) (z \in real).
proof: Proof. rewrite (sameP (Creal_ImP z) eqP) -(can_eq (mulKf neq0Ci)) mulr0. by rewrite -(inj_eq (addrI ('Re z))) addr0 -Crect eq_sym; apply: eqP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)