Definition Fplus (x y : float) :=
  Float
    (Fnum x * Zpower_nat radix (Zabs_nat (Fexp x - Zmin (Fexp x) (Fexp y))) +
     Fnum y * Zpower_nat radix (Zabs_nat (Fexp y - Zmin (Fexp x) (Fexp y))))
    (Zmin (Fexp x) (Fexp y)).

Theorem Fplus_correct : forall x y : float, Fplus x y = (x + y)%R :>R.