(** Overflow and underflow conditions. *)

Lemma round_integer_underflow:
forall (base: radix) e m,
e < 0 ->
e * Z.log2 base + Z.log2_up (Zpos m) < emin ->
round radix2 fexp (round_mode mode_NE) (Z2R (Zpos m) * bpow base e) = 0%R.