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