proposition: Lemma normC_rect : {in real &, forall x y, `|x + 'i * y| = sqrtC (x ^+ 2 + y ^+ 2)}.
proof: Proof. by move=> x y Rx Ry; rewrite /= normC_def -normCK normC2_rect. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)