proposition: Lemma scalar_mx_is_diag a : is_diag_mx (a%:M).
proof: Proof. by rewrite -diag_const_mx diag_mx_is_diag. 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)