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

Lemma filterdiff_scal_l_fct : forall {F} {FF : Filter F} (x : V) (f : U -> K) lf,
filterdiff f F lf ->
filterdiff (fun u => scal (f u) x) F (fun u => scal (lf u) x).