proposition: Lemma is_cvg_geometric_series (R : archiFieldType) (a z : R) : `|z| < 1 -> cvgn (series (geometric a z)).
proof: Proof. by move=> /cvg_geometric_series/cvgP; apply. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(set_interval) reals ereal signed topology normedtype landau