case (Rcase_abs x); intros H1.
unfold FtoRradix in |- *; apply Fabs_correct2; auto with arith.
apply Rlt_le; auto.
unfold FtoRradix in |- *; apply Fabs_correct1; auto with arith.
apply Rge_le; auto.
Qed.

Theorem RleFexpFabs :
forall p : float, p <> 0%R :>R -> (Float 1%nat (Fexp p) <= Fabs p)%R.