proposition: Lemma ex_pseries_derive (a : nat -> R) (x : R) : Rbar_lt (Finite (Rabs x)) (CV_radius a) -> ex_pseries (PS_derive a) x.
proof: Proof. move => Hx. eexists. by apply is_pseries_derive. Qed.
imports: Coq(Reals Psatz ssreflect) Rcomplements Rbar Lim_seq Lub Hierarchy Continuity Derive Seq_fct Series