fact: Definition lin_mx (f : 'M[R]_(m1, n1) -> 'M[R]_(m2, n2)) := lin1_mx (mxvec \o f \o vec_mx).
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)