proposition: Lemma is_pseries_R (a : nat -> R) (x l : R) : is_pseries a x l <-> is_series (fun n : nat => a n * x ^ n) l.
proof: Proof. split ; apply is_series_ext ; intros n ; rewrite pow_n_pow /= ; apply Rmult_comm. Qed.
imports: Coq(Reals Psatz ssreflect) Rcomplements Rbar Lim_seq Lub Hierarchy Continuity Derive Seq_fct Series