proposition: Lemma fdist_gt0 d a : (d a != 0) <-> (0 < d a).
proof: Proof. split => H; last by rewrite gt_eqF. by rewrite lt_neqAle eq_sym H /=. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(all_algebra vector reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(Rstruct) ssrR logb realType_ext ssr_ext ssralg_ext bigop_ext