From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: bignum branch Date: Sat, 04 Aug 2018 09:18:07 +0300 Message-ID: <83muu2u02o.fsf@gnu.org> References: <87o9fbbw1t.fsf@tromey.com> <86in5jdj49.fsf@gmail.com> <83wotxaiwi.fsf@gnu.org> <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> NNTP-Posting-Host: blaine.gmane.org X-Trace: blaine.gmane.org 1533363418 9002 195.159.176.226 (4 Aug 2018 06:16:58 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 4 Aug 2018 06:16:58 +0000 (UTC) Cc: tom@tromey.com, andrewjmoreton@gmail.com, emacs-devel@gnu.org To: Paul Eggert Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Aug 04 08:16:54 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 1flprx-0002H3-9u for ged-emacs-devel@m.gmane.org; Sat, 04 Aug 2018 08:16:53 +0200 Original-Received: from localhost ([::1]:54066 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1flpu3-0005VJ-Lv for ged-emacs-devel@m.gmane.org; Sat, 04 Aug 2018 02:19:03 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:49031) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1flptL-0005VE-T3 for emacs-devel@gnu.org; Sat, 04 Aug 2018 02:18:21 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1flptI-0004SB-OR for emacs-devel@gnu.org; Sat, 04 Aug 2018 02:18:19 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:39931) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1flptI-0004Rw-K6; Sat, 04 Aug 2018 02:18:16 -0400 Original-Received: from [176.228.60.248] (port=2212 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1flptI-0007aw-2P; Sat, 04 Aug 2018 02:18:16 -0400 In-reply-to: (message from Paul Eggert on Fri, 3 Aug 2018 18:22:10 -0700) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e 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:228145 Archived-At: > From: Paul Eggert > Date: Fri, 3 Aug 2018 18:22:10 -0700 > Cc: Eli Zaretskii , Andy Moreton , > emacs-devel@gnu.org > > Tom Tromey wrote: > > Paul> min and max propagate any NaNs they find. > > > > This part I don't understand, since my mental mode of min/max is that > > they are iteratively applying < or > > > The goal is more to have useful max and min functions than to have a particular > implementation tactic. Returning a NaN is more useful, since it warns the caller > that the min or max expression doesn't have a reasonable numeric interpretation. 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. 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. Thanks.