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(*         *      The Rocq Prover / The Rocq Development Team           *)
(*  v      *         Copyright INRIA, CNRS and contributors             *)
(* <O___,, * (see version control and CREDITS file for authors & dates) *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
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Local Open Scope R_scope.
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(* Various versions of the criterion of D'Alembert *)
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(** Convergence of power series in D(O,1/k) k=0 is described in Alembert_C3     *)
Lemma Alembert_C6 :
forall (An:nat -> R) (x k:R),
0 < k ->
(forall n:nat, An n <> 0) ->
Un_cv (fun n:nat => Rabs (An (S n) / An n)) k ->
Rabs x < / k -> { l:R | Pser An x l }.