proposition: Lemma supp_twisted y : supp (twisted y) = supp y.
proof: Proof. apply/setP => i; by rewrite inE mxE mulf_eq0 negb_or expf_neq0 // andbT inE. Qed.
imports: mathcomp(all_ssreflect ssralg finalg poly polydiv cyclic) mathcomp(perm matrix mxpoly) ssr_ext ssralg_ext cyclic_code dft