Definition RInt (f : R -> V) (a b : R) := iota (is_RInt f a b).

Lemma RInt_comp_lin (f : R -> V) (u v a b : R) : ex_RInt f (u * a + v) (u * b + v) -> RInt (fun y => scal u (f (u * y + v))) a b = RInt f (u * a + v) (u * b + v).