fact: Definition swizzle_mx k (A : 'M[V]_(m, n)) := \matrix[k]_(i, j) A (f i j) (g i j).
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)