X-Authentication-Warning: acp3bf.physik.rwth-aachen.de: broeker owned process doing -bs Date: Wed, 22 Mar 2000 15:44:33 +0100 (MET) From: Hans-Bernhard Broeker X-Sender: broeker AT acp3bf To: djgpp-workers AT delorie DOT com Subject: Re: Unnormals??? In-Reply-To: <200003221407.JAA07300@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, 22 Mar 2000, Dieter Buerssner wrote: > On 22 Mar 00, Eli Zaretskii wrote: > > When converted to a long double, these two have the following bit > > patterns: > > > > pos_nanshort = 7fff 0001 0000 0000 > > neg_nanshort = ffff 0001 0000 0000 > > These are indeed unnormals: their mantissa has a zero MSB. > > I think, they are not unnormals. I think this discussion has shown, > that unnormals must have a finite exponent. Not necessarily. My literature is not decisive on this, as pointed out before, but I take these numbers are the so-called 'pseudo-NaNs' mentioned by the book, but without a definition what that really is. They are not normalized, obviously . If you do normalize them, you end up with a bit pattern that is not a NaN any more, but a regular (albeit large) number). 7fff 0001 0000 0000 0000 e.g., would normalize into 7ffc 1000 0000 0000 0000, which is a large, but finite value. So they are 'Pseudo-NaN', in the sense that they look a bit like NaN, but aren't, as they do not have the leading '1' bit in the mantissa required for NaNs, or any number that is not an unnormal. > I think it should, and it also did this before the unnormal check was > added. (Yes, it was my error not thinking about the unnormal case when > adding long double support to _doprint.) Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de) Even if all the snow were burnt, ashes would remain.