proposition: Lemma mx11_scalar (A : 'M_1) : A = (A 0 0)%:M.
proof: Proof. by apply/rowP=> j; rewrite ord1 mxE. 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)