proposition: Lemma ReM x y : 'Re (x * y) = 'Re x * 'Re y - 'Im x * 'Im y.
proof: Proof. by rewrite -ImMil mulrCA ImM ImMil ReMil mulNr ['Im _ * _]mulrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)