proposition: Lemma trmx_scalar : forall n a, (a%:M)^T === @scalar_mx n a.
proof: Proof. by move=> n a i j; rewrite/trmx/null_mx/addmx/oppmx/scalemx/scalar_mx/mulmx eq_sym; reflexivity. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq choice fintype finfun bigops ssralg groups perm zmodp morphisms Ring RingClass bigopsClass Setoid Morphisms