(** * Geometric series *)

(* Specifications: *)
Lemma is_series_geom (q : R) :
Rabs q < 1 -> is_series  (fun n => q ^ n) (/ (1-q)).
Lemma ex_series_geom (q : R) :
Rabs q < 1 -> ex_series  (fun n => q ^ n).
Lemma Series_geom (q : R) :
Rabs q < 1 -> Series (fun n => q ^ n) = / (1-q).