(** Equivalence with standard library Reals *)

Lemma CV_radius_Reals_2 (a : nat -> R) (x : R) :
Rbar_lt (Finite (Rabs x)) (CV_radius a)
-> exists r : posreal, CVU (fun n x => sum_f_R0 (fun k => a k * x ^ k) n) (PSeries a) x r.