proposition: Lemma scalemxA x y A : x *m: (y *m: A) = (x * y) *m: A.
proof: Proof. by apply/matrixP=> i j; rewrite !mxE mulrA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)