Date: Wed, 15 Mar 2000 19:12:28 +0200 (IST) From: Eli Zaretskii X-Sender: eliz AT is To: Dieter Buerssner cc: djgpp-workers AT delorie DOT com Subject: Re: Unnormals??? In-Reply-To: <200003151627.LAA20064@delorie.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Reply-To: djgpp-workers AT delorie DOT com Errors-To: dj-admin AT delorie DOT com X-Mailing-List: djgpp-workers AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On Wed, 15 Mar 2000, Dieter Buerssner wrote: > So there will be > bitpatterns, with a finite exponent and a non set msb in the > mantissa. We called those unnormal in this threat. They could in > principle be renormalized (when the mantissa is not zero). But I > think, they are just invalid. Yes, these numbers are invalid. They cannot result from any FP operation, only from passing arbitrary buffers to functions or casting such buffers to long double. > They are not numbers so we could call them NaNs. I don't think this is a good idea, because, unlike NaNs, unnormals *always* mean there's a bug lurking somewhere. So it makes sense to tell the user explicitly about this. If we print NaN, the user cannot know whether this is the normal IEEE NaN with its distinct bit pattern or something else. > Perhaps there is a reader of this list, who has access to IEEE > floating point standards, and can check whether it allows an > unnormalized mantissa with finite exponent for the extended > IEEE type. Note that C9X and IEEE are two different standards which don't necessarily coincide.