proposition: Lemma mul_rV_lin1 u : u *m lin1_mx f = f u.
proof: Proof. rewrite {2}[u]matrix_sum_delta big_ord1 linear_sum; apply/rowP=> i. by rewrite mxE summxE; apply: eq_bigr => j _; rewrite linearZ !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)