proposition: Lemma cent_mx_fun_is_linear : linear cent_mx_fun.
proof: Proof. move=> a A B; apply/row_matrixP=> i; rewrite linearP row_mul mul_rV_lin. rewrite /= [row i _ as v in a *: v]row_mul mul_rV_lin row_mul mul_rV_lin. by rewrite -linearP -(linearP (mulmx (vec_mx (row i R)) \- mulmxr _)). 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 finalg zmodp matrix)