(** the most useful one: R -> F *)
Definition round x :=
  F2R (Float beta (rnd (scaled_mantissa x)) (canonic_exp x)).

(* Specifications: *)
Theorem round_bounded_large_pos : forall x ex, (fexp ex < ex)%Z -> (bpow (ex - 1) <= x < bpow ex)%R -> (bpow (ex - 1) <= round x <= bpow ex)%R.
Theorem round_bounded_small_pos : forall x ex, (ex <= fexp ex)%Z -> (bpow (ex - 1) <= x < bpow ex)%R -> round x = 0%R \/ round x = bpow (fexp ex).
Theorem round_le_pos : forall x y, (0 < x)%R -> (x <= y)%R -> (round x <= round y)%R.
Theorem round_generic : forall x, generic_format x -> round x = x.
Theorem round_0 : round 0 = 0%R.
Theorem exp_small_round_0_pos : forall x ex, (bpow (ex - 1) <= x < bpow ex)%R -> round x = 0%R -> (ex <= fexp ex)%Z .
Theorem generic_format_round_pos : forall x, (0 < x)%R -> generic_format (round x).
Theorem round_ext : forall rnd1 rnd2, ( forall x, rnd1 x = rnd2 x ) -> forall x, round rnd1 x = round rnd2 x.