Definition Fulp (p : float) :=
  powerRZ radix (Fexp (Fnormalize radix b precision p)).

Theorem RleRoundedLessR0 : forall (P : R -> float -> Prop) (p : float) (r : R), RoundedModeP b radix P -> P r p -> (r <= 0)%R -> (p <= 0)%R.