proposition: Lemma real_mulr_sign_norm x : x \is real -> (-1) ^+ (x < 0)%R * `|x| = x.
proof: Proof. by move/realEsign. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)