proposition: Lemma scale_mulidr a n m (I : 'cV[R]_n) (J : 'cV[R]_m) : (a *: (I *i J) :=: (a *: I) *i J)%IS.
proof: Proof. by rewrite scale_trmx scale_mxvec -!mul_scalar_mx /mulid -mulmxA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice fingroup) mathcomp(matrix bigop zmodp mxalgebra poly) ssrcomplements