fact: Definition idft_coef (f : 'rV[F]_n) (j : nat) := (n%:R^-1) * \sum_(k < n) (f ``_ k) * a ^- (j * k).
imports: mathcomp(all_ssreflect ssralg poly polydiv zmodp) mathcomp(matrix mxalgebra mxpoly vector cyclic perm) ssr_ext ssralg_ext hamming