fact: Definition GRS_PCM_polynomial := @GRS.PCM _ F a b r.
imports: mathcomp(all_ssreflect ssralg finalg poly polydiv) mathcomp(cyclic perm matrix mxpoly vector mxalgebra zmodp) mathcomp(finfield falgebra fieldext) ssr_ext ssralg_ext vandermonde linearcode dft poly_decoding grs bch