From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Achim Gratz Newsgroups: gmane.emacs.devel Subject: Re: bignum branch Date: Sat, 04 Aug 2018 12:49:24 +0200 Organization: Linux Private Site Message-ID: <871sbez9sb.fsf@Rainer.invalid> References: <87o9fbbw1t.fsf@tromey.com> <86k1pxmvmx.fsf@gmail.com> <87efg4a9xc.fsf@tromey.com> <87a7qr8cz7.fsf@tromey.com> <86tvoy3je9.fsf@gmail.com> <86bmb0vbxf.fsf@gmail.com> <87k1pnfcg1.fsf@tromey.com> <86sh4b1833.fsf@gmail.com> <861sbgz3dm.fsf@gmail.com> <83a7q4ufxp.fsf@gnu.org> <86in4resc8.fsf@gmail.com> <831sbfvl11.fsf@gnu.org> <8636vv7ohh.fsf@gmail.com> <83y3dntwsw.fsf@gnu.org> <83wot7tkdh.fsf@gnu.org> <87y3dnyzkl.fsf@tromey.com> <42060bb4-3535-3b03-e007-0ae68134a30b@cs.ucla.edu> <87tvobywph.fsf@tromey.com> <83muu2u02o.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1533379666 27972 195.159.176.226 (4 Aug 2018 10:47:46 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 4 Aug 2018 10:47:46 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Aug 04 12:47:42 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1flu60-00079Z-Pm for ged-emacs-devel@m.gmane.org; Sat, 04 Aug 2018 12:47:40 +0200 Original-Received: from localhost ([::1]:54597 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1flu87-0006xH-7j for ged-emacs-devel@m.gmane.org; Sat, 04 Aug 2018 06:49:51 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:50512) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1flu7z-0006qL-SF for emacs-devel@gnu.org; Sat, 04 Aug 2018 06:49:44 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1flu7w-0003ID-MF for emacs-devel@gnu.org; Sat, 04 Aug 2018 06:49:43 -0400 Original-Received: from [195.159.176.226] (port=38116 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1flu7w-0003G9-Ci for emacs-devel@gnu.org; Sat, 04 Aug 2018 06:49:40 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1flu5i-0006r5-GB for emacs-devel@gnu.org; Sat, 04 Aug 2018 12:47:22 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 30 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:OvPRTI2YR9gHUaM7pFBJN7EejF4= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:228149 Archived-At: Eli Zaretskii writes: > There's a certain tension here between people who are used to do IEEE > compliant FP math in other languages, and the rest of us. The former > will want the IEEE semantics of NaNs, which is what surprised Tom; the > latter will probably be surprised like Tom was. The semantics of NaN have not much to do with IEEE754 and a lot with how you do error handling, which shouldn't be a surprise to any programmer. > I don't see how we can fix this dilemma better than we already did, > with making sure eql compares NaNs as equal. I do think we should > document the special behavior of NaNs, because many Emacs users will > not be aware of these subtleties. Again, comparing the representations of an NaN (binary or otherwise) is fair game. The NaN itself, as long as it propagates through a chain of numerical computations, needs to be preserved; otherwise it'd be an exercise in futility to produce them in the first place. If you don't want to deal with NaN at all, there are other methods of handling numerical domain errors, but they are usually worse (and often much more so) than the alternative. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Wavetables for the Terratec KOMPLEXER: http://Synth.Stromeko.net/Downloads.html#KomplexerWaves