fact: Definition RS_mod (y : 'rV[F]_n) t := - \sum_(i in supp y) y ``_ i *: (\prod_(j in supp y :\ i) (1 - a ^+ j *: 'X) * - (a ^+ (t.+1 * i))%:P).
imports: mathcomp(all_ssreflect ssralg finalg poly polydiv cyclic) mathcomp(perm matrix mxpoly vector mxalgebra zmodp) ssr_ext ssralg_ext poly_ext channel_code decoding linearcode hamming dft poly_decoding euclid grs cyclic_code