proposition: Lemma normrMsign s x : `|(-1) ^+ s * x| = `|x|.
proof: Proof. by rewrite normrM normr_sign mul1r. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)