proposition: Lemma deriveN f (x v : V) : derivable f x v -> 'D_v (- f) x = - 'D_v f x.
proof: Proof. by move=> df; apply: cvg_lim (der_opp df). Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum matrix interval) mathcomp(mathcomp_extra boolp classical_sets functions) reals signed topology prodnormedzmodule normedtype landau forms