proposition: Lemma scalerA' a b v : scaleW a (scaleW b v) = scaleW (a * b) v.
proof: Proof. by apply: val_inj; rewrite !SubK scalerA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)