(** * Rbar_abs *)
Definition Rbar_abs (x : Rbar) :=
match x with
| Finite x => Finite (Rabs x)
| _ => p_infty
end.

Lemma Rbar_abs_lt_between (x y : Rbar) :
Rbar_lt (Rbar_abs x) y <-> (Rbar_lt (Rbar_opp y) x /\ Rbar_lt x y).