proposition: Lemma derivable_pt_const : forall a x:C, derivable_pt (fct_cte a) x.
proof: Proof. intros; unfold derivable_pt in |- *. exists 0. apply derivable_pt_lim_const. Qed.
imports: MyRIneq Rinterval Ranalysis_def Ranalysis_def_simpl Ranalysis_continuity Ranalysis_derivability Ranalysis_usual Ranalysis_facts Ranalysis_MVT Canalysis_diff Cprop_base Cnorm Ctacfield Cmet Canalysis_def Cderiv