Definition sf_SF_val_fun (f : R -> R) (a b : R) (n : nat) : StepFun a b.

Lemma SF_val_subdiv_val (f : R -> R) (a b : R) (n : nat) :
subdivision_val (sf_SF_val_fun f a b n) =
match (Rle_dec a b) with
| left _ => seq2Rlist (SF_val_ly f a b n)
| right _ => seq2Rlist (SF_val_ly f b a n)
end.