fact: Definition tensmx {m n p q : nat} (A : 'M_(m, n)) (B : 'M_(p, q)) : 'M[R]_(_,_) := nosimpl (\matrix_(i, j) (A (mxtens_unindex i).1 (mxtens_unindex j).1 * B (mxtens_unindex i).2 (mxtens_unindex j).2)).
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop ssralg matrix zmodp div)