proposition: Lemma mxvecE A i j : mxvec A 0 (mxvec_index i j) = A i j.
proof: Proof. by rewrite castmxE mxE cast_ordK enum_rankK. 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)