From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Drew Adams" Newsgroups: gmane.emacs.devel Subject: RE: Q on NaN Date: Fri, 24 Jun 2005 12:46:43 -0700 Message-ID: References: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Trace: sea.gmane.org 1119643480 13988 80.91.229.2 (24 Jun 2005 20:04:40 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Fri, 24 Jun 2005 20:04:40 +0000 (UTC) Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jun 24 22:04:38 2005 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DluOw-0000jk-42 for ged-emacs-devel@m.gmane.org; Fri, 24 Jun 2005 22:03:46 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DluW1-0002FF-Rz for ged-emacs-devel@m.gmane.org; Fri, 24 Jun 2005 16:11:05 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1DluVC-00022z-Oj for emacs-devel@gnu.org; Fri, 24 Jun 2005 16:10:14 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1DluQV-0000yp-IN for emacs-devel@gnu.org; Fri, 24 Jun 2005 16:05:27 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DluQS-0000pC-24 for emacs-devel@gnu.org; Fri, 24 Jun 2005 16:05:20 -0400 Original-Received: from [148.87.122.33] (helo=rgminet04.oracle.com) by monty-python.gnu.org with esmtp (TLS-1.0:DHE_RSA_3DES_EDE_CBC_SHA:24) (Exim 4.34) id 1DluC9-000735-3N for emacs-devel@gnu.org; Fri, 24 Jun 2005 15:50:33 -0400 Original-Received: from rgminet04.oracle.com (localhost [127.0.0.1]) by rgminet04.oracle.com (Switch-3.1.6/Switch-3.1.6) with ESMTP id j5OJkmVv001429 for ; Fri, 24 Jun 2005 13:46:48 -0600 Original-Received: from rgmsgw300.us.oracle.com (rgmsgw300.us.oracle.com [138.1.186.49]) by rgminet04.oracle.com (Switch-3.1.6/Switch-3.1.6) with ESMTP id j5OJklah001407 for ; Fri, 24 Jun 2005 13:46:47 -0600 Original-Received: from rgmsgw300.us.oracle.com (localhost [127.0.0.1]) by rgmsgw300.us.oracle.com (Switch-3.1.4/Switch-3.1.0) with ESMTP id j5OJkli1024512 for ; Fri, 24 Jun 2005 13:46:47 -0600 Original-Received: from dradamslap (dhcp-amer-whq-csvpn-gw3-141-144-80-138.vpn.oracle.com [141.144.80.138]) by rgmsgw300.us.oracle.com (Switch-3.1.4/Switch-3.1.0) with SMTP id j5OJkkQU024495 (version=TLSv1/SSLv3 cipher=RC4-MD5 bits=128 verify=NO) for ; Fri, 24 Jun 2005 13:46:46 -0600 Original-To: "Emacs-Devel" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 Importance: Normal X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:39452 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:39452 Still following up on my own post: (condition-case nil (setq foo (/ 0.0 0.0)) (arith-error nil)) In older versions of Emacs (at least prior to April 2005 CVS), this would evaluate to nil. Now, it evaluates to -0.0NaN. I can modify the code like so: (and (condition-case nil (setq foo (/ 0.0 0.0)) (arith-error nil)) (bar foo)) ; foo must be a number, not a NaN What function do I use for bar? `numberp' doesn't work, since (numberp -0.0NaN) is non-nil. To make the point simpler: (numberp (/0.0 0.0)) returns t. That seems like a bug to me. If this is not considered a bug, and `numberp' should return non-nil for NaN, as it currently does, then what are all the possible NaN values to test? The Elisp manual mentions that the read syntax for (/ 0.0 0.0) is 0.0e+NaN. On my system it is in fact -0.0e+NaN. Are there additional NaN values, or would this be a sufficient test for NaN-ness, to replace `numberp': (let ((foo (/0.0 0.0))) (and (not (equal -0.0e+NaN foo)) (not (equal 0.0e+NaN foo)))) (Note that (= -0.0e+NaN foo) returns nil, while (equal -0.0e+NaN foo) returns `t'.)