fact: Definition changes_itv_poly a b (p : seq {poly R}) := (changes_horner p a)%:Z - (changes_horner p b)%:Z.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice path fintype) mathcomp(div bigop order ssralg poly polydiv ssrnum perm zmodp ssrint) mathcomp(polyorder polyrcf interval matrix mxtens)