fact: Definition Xderive_pt f x y' := match x, y', f x with | Xreal r, Xreal d, Xreal _ => forall v, derivable_pt_lim (proj_fun v f) r d | _, Xnan, _ => True | _, _, _ => False end.
imports: Coq(Reals) Flocq(Raux) Stdlib Xreal