proposition: Lemma scaler_sign (b : bool) v: (-1) ^+ b *: v = (if b then - v else v).
proof: Proof. by case: b; rewrite ?scaleNr scale1r. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)