proposition: Lemma eval_col_mx e : eval_mx e (col_mx A B) = col_mx (eval_mx e A) (eval_mx e B).
proof: Proof. by apply/matrixP=> i j; do 2![rewrite !mxE //; case: split => ?]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(div fintype tuple finfun bigop fingroup perm) mathcomp(ssralg zmodp matrix mxalgebra poly polydiv)