From 3962811745560659220 X-Google-Language: ENGLISH,ASCII X-Google-Thread: f78e5,d93488bb970aa444 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2001-06-11 05:57:01 PST Path: archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!newsfeeds.belnet.be!news.belnet.be!colt.net!dispose.news.demon.net!news.demon.co.uk!demon!mail2news.demon.co.uk!not-for-mail From: kanze@gabi-soft.de (James Kanze) Newsgroups: comp.std.c++ Subject: Re: How to test for NaNs and infinites? Date: Mon, 11 Jun 2001 12:56:06 GMT Organization: http://groups.google.com/ Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: References: <3B176D2F.70C3E7F7@meteo.fr> X-Trace: mail2news.demon.co.uk 992264183 mail2news:28970 mail2news mail2news.demon.co.uk X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit NNTP-Posting-Date: 11 Jun 2001 12:53:55 GMT Lines: 47 Xref: archiver1.google.com comp.std.c++:5923 "Scott Robert Ladd" wrote in message news:... > "Stephen Clamage" wrote: > > There are no provisions in the C++ standard. The standard makes > > almost no requirements on floating-point types. Implementations > > are not required to support NaN or infinity. If support is > > provided, it can take any form that the implementation chooses. > Is this a good thing? Especially in light of the numeric support now > provided by C99? > While I understand the portability reasons for leaving NaNs and > infinities unspecified, I think the scheme implemented by C99 > (sec. 7.12) is quite reasonable, if not entirely "C++"ish in nature. > I note that Zortech C++ supported the "C Numeric Extensions" long > ago (I wrote the numeric programming docs for Zortech/Symantec, in > fact, which is darned close to what C99 implemented). > Perhaps someone can explain why the C99 numerical conventions cannot > be safely implemented in C++. They probably can. The current C++ standard could not reference C99, since it was published in 1998. I'm just guessing, but I could imagine that part of the reason the C++ committee didn't do more with regards to IEEE floating point is because they knew that the C committee was working on it, and felt that to be the more appropriate place. (Presumably, the C which the next version of the C++ will refer to will be C99.) In the meantime, most C++ compilers are strongly coupled to C compilers; I would be very surprised if any of these didn't implement the new C numeric stuff in C++, as an extension. -- James Kanze mailto:kanze@gabi-soft.de Conseils en informatique orient�e objet/ Beratung in objektorientierter Datenverarbeitung Ziegelh�ttenweg 17a, 60598 Frankfurt, Germany Tel. +49(069)63198627 --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.research.att.com/~austern/csc/faq.html ]