proposition: Lemma is_cvgeN f : cvg (f @ F) -> cvg (\- f @ F).
proof: Proof. by move=> /cvg_ex[l fl]; apply: (cvgP (- l)); exact: cvgeN. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrint ssrnum finmap matrix) mathcomp(rat interval zmodp vector fieldext falgebra) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality set_interval Rstruct) ereal reals signed topology prodnormedzmodule