proposition: Lemma mxtrace1 : \tr (1%:M : 'M[R]_n) = n%:R.
proof: Proof. exact: mxtrace_scalar. 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)