Notation bpow e := (bpow beta e).Notation format := (generic_format beta (FLT_exp emin prec)).Notation cexp := (canonic_exp beta (FLT_exp emin prec)).

Theorem mult_error_FLT : forall x y, format x -> format y -> (x*y = 0)%R \/ (bpow (emin + 2*prec - 1) <= Rabs (x * y))%R -> format (round beta (FLT_exp emin prec) rnd (x * y) - (x * y))%R.