proposition: Lemma invC_Crect x y : (x + 'i * y)^-1 = (x^* - 'i * y^*) / `|x + 'i * y| ^+ 2.
proof: Proof. by rewrite /= invC_norm mulrC !rmorphE rmorphM /= conjCi mulNr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)