proposition: Lemma mulz_sign_abs m : ((-1) ^+ (m < 0)%R * `|m|%:Z)%R = m.
proof: Proof. by rewrite abszE mulr_sign_norm. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)