Section Operations_fct.
Context {K : AbsRing} {U V : NormedModule K}.

Lemma ex_filterdiff_scal_r_fct : forall {F} {FF : Filter F} (k : K) (f : U -> V),
(forall (n m : K), mult n m = mult m n) ->
ex_filterdiff f F ->
ex_filterdiff (fun x => scal k (f x)) F.