From -296087983128404027 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,d93488bb970aa444 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2001-06-04 13:04:01 PST Path: archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!dispose.news.demon.net!news.demon.co.uk!demon!mail2news.demon.co.uk!not-for-mail From: "Scott Robert Ladd" Newsgroups: comp.std.c++ Subject: Re: How to test for NaNs and infinites? Date: Mon, 4 Jun 2001 20:03:06 GMT Organization: RoadRunner - TampaBay Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: References: <3B176D2F.70C3E7F7@meteo.fr> X-Trace: mail2news.demon.co.uk 991684990 mail2news:14030 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) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 NNTP-Posting-Date: Mon, 04 Jun 2001 10:10:27 EDT Lines: 39 Xref: archiver1.google.com comp.std.c++:5664 "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++. > Other standards provide definitions and APIs for floating-point, and > an implementation could choose to follow one or more of them. Perhaps extension of the is_iec559 would be reasonable? On the other hand, this is one area where I don't see why C99 and C++0X cannot be compatible. -- Scott Robert Ladd Master of Complexity Destroyer of Order and Chaos http://www.coyotegulch.com --- [ 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 ]