fact: Definition sqrt_helper (xi zi : FF) := (if (Fneg0 (lower zi)) then Fpos0 (lower xi) else Fle2 (Fmult2 (lower zi) (lower zi)) (lower xi)) && Fpos0 (upper zi) && Fle2 (upper xi) (Fmult2 (upper zi) (upper zi)).
imports: Gappa_common Gappa_decimal