Definition RInt_val (f : R -> V) (a b : R) (n : nat) :=
  Riemann_sum f (SF_seq_f2 (fun x y => (x + y) / 2) (unif_part a b n)).

Lemma RInt_val_comp_lin (f : R -> V) (u v : R) (a b : R) (n : nat) : scal u (RInt_val (fun x => f (u * x + v)) a b n) = RInt_val f (u * a + v) (u * b + v) n.