(** * Definitions on [R] *)

Definition Derive (f : R -> R) (x : R) := real (Lim (fun h => (f (x+h) - f x)/h) 0).

Lemma norm_le_prod_norm_2 {K : AbsRing} {U V : NormedModule K} (x : U * V) : norm (snd x) <= norm x.