fact: Definition split_poly n b p := \poly_(i < n) \poly_(j < b) p`_(i * b + j).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div fintype tuple) mathcomp(finfun bigop fingroup perm ssralg zmodp matrix mxalgebra) mathcomp(poly polydiv mxpoly)