fact: Definition ln prec xi := match xi with | Ibnd xl xu => if F'.lt' F.zero xl then Ibnd (lower (T.ln_fast prec xl)) (if F.real xu then upper (T.ln_fast prec xu) else F.nan) else Inan | Inan => Inan end.
imports: Coq(Reals Psatz) Xreal Basic Sig Interval Float Transcend