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: Using the GNU GMP Library for Bignums in Emacs Date: Sun, 22 Jul 2018 21:57:27 +0200 Organization: Linux Private Site Message-ID: <87pnzfhwm0.fsf@Rainer.invalid> References: <29f933ac-a6bf-8742-66a7-0a9d6d3e5a88@disroot.org> <83bmecy6fx.fsf@gnu.org> <0d3175d8-d996-651e-b221-71978bde3a65@cs.ucla.edu> <87tvpdnzgy.fsf@tromey.com> <4c2a814f-c254-29e5-39cf-11b5f2e5c9c8@cs.ucla.edu> <49d8ba62-c9a5-9203-d882-8e900b441ff3@cs.ucla.edu> <8e0320d9-e0d0-2b57-57cc-2df4399f133c@cs.ucla.edu> <87lgaio7xd.fsf@tromey.com> <877em1cb0i.fsf@tromey.com> <765767b2-d2e5-a9a6-f724-d58ecf4847bb@cs.ucla.edu> <1452F858-C7FD-4AEB-BB85-D874692F918F@raeburn.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1532289339 8247 195.159.176.226 (22 Jul 2018 19:55:39 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 22 Jul 2018 19:55:39 +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 Sun Jul 22 21:55:35 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 1fhKS7-00024z-HD for ged-emacs-devel@m.gmane.org; Sun, 22 Jul 2018 21:55:35 +0200 Original-Received: from localhost ([::1]:57311 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fhKUE-0000fE-83 for ged-emacs-devel@m.gmane.org; Sun, 22 Jul 2018 15:57:46 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:40917) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fhKU7-0000f7-QC for emacs-devel@gnu.org; Sun, 22 Jul 2018 15:57:40 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fhKU3-0000Gl-0K for emacs-devel@gnu.org; Sun, 22 Jul 2018 15:57:39 -0400 Original-Received: from [195.159.176.226] (port=49427 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fhKU2-0000GT-Mf for emacs-devel@gnu.org; Sun, 22 Jul 2018 15:57:34 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1fhKRt-0001r4-Rf for emacs-devel@gnu.org; Sun, 22 Jul 2018 21:55:21 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 30 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:GMymp8BVG+j73Ot+vS+wIeo/V7U= 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:227687 Archived-At: Ken Raeburn writes: > If we’re going to treat NaNs as having distinguishable bit patterns so > we can tell whether two are the same or not, should we also have > printable/readable forms that distinguish them? If not, how do we > create and use distinguishable NaNs? That would expose the NaN payload, using the non-specified bits of the mantissa of an NaN to transport (sideband) information. You will probably find that no one really expects these bits to be used… > For that matter, are we guaranteed that operations like (/ 0.0 0.0) > will always generate NaNs with the same bit pattern? On the same platform? Likely. On different platforms, surely not. > I would’ve guessed that it might be preferable to go the other > direction, and use one canonical NaN value in Lisp, which would thus > always be eq/eql to all other NaN expressions. Ignoring the payload bits would probably be OK, but that still gives you at least two different NaN (positive and negative) to deal with. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ SD adaptation for Waldorf Blofeld V1.15B11: http://Synth.Stromeko.net/Downloads.html#WaldorfSDada