From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: David Ongaro Newsgroups: gmane.emacs.bugs Subject: bug#41279: 26.3; Calc: sum(gcd(0,n),n,-1,-1) evaluates to -1 Date: Fri, 15 May 2020 10:44:07 -0700 Message-ID: <20621430-4DFE-4E40-A616-9D404DDBB2BF@hamburg.de> References: <7D48D15C-1F8E-41C8-9B1C-650215C8101D@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="68063"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Microsoft-MacOutlook/16.37.20051002 Cc: 41279@debbugs.gnu.org To: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Fri May 15 19:45:21 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jZeOf-000Hcq-7t for geb-bug-gnu-emacs@m.gmane-mx.org; Fri, 15 May 2020 19:45:21 +0200 Original-Received: from localhost ([::1]:35188 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jZeOe-00042k-8g for geb-bug-gnu-emacs@m.gmane-mx.org; Fri, 15 May 2020 13:45:20 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:47562) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jZeOM-00040G-8g for bug-gnu-emacs@gnu.org; Fri, 15 May 2020 13:45:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:55365) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jZeOL-0006Br-UJ for bug-gnu-emacs@gnu.org; Fri, 15 May 2020 13:45:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jZeOL-0002Ab-Sk for bug-gnu-emacs@gnu.org; Fri, 15 May 2020 13:45:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: David Ongaro Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 15 May 2020 17:45:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 41279 X-GNU-PR-Package: emacs Original-Received: via spool by 41279-submit@debbugs.gnu.org id=B41279.15895646638267 (code B ref 41279); Fri, 15 May 2020 17:45:01 +0000 Original-Received: (at 41279) by debbugs.gnu.org; 15 May 2020 17:44:23 +0000 Original-Received: from localhost ([127.0.0.1]:38675 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jZeNj-00029H-Mt for submit@debbugs.gnu.org; Fri, 15 May 2020 13:44:23 -0400 Original-Received: from longisland.ops.eusc.inter.net ([84.23.254.153]:36516) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jZeNi-000293-D7 for 41279@debbugs.gnu.org; Fri, 15 May 2020 13:44:23 -0400 Original-X-Trace: 4c7c64617669642e6f6e6761726f4068616d627572672e64657c3137342e32312e 3130372e3134397c316a5a654e592d303030344a772d52397c3135383935363436 3533 Original-Received: from longisland.ops.eusc.inter.net ([10.153.10.15] helo=localhost) by longisland.ops.eusc.inter.net with esmtpsa (Exim 4.93.0.4) id 1jZeNY-0004Jw-R9; Fri, 15 May 2020 19:44:13 +0200 Thread-Topic: bug#41279: 26.3; Calc: sum(gcd(0,n),n,-1,-1) evaluates to -1 In-Reply-To: <7D48D15C-1F8E-41C8-9B1C-650215C8101D@acm.org> X-SA-Exim-Connect-IP: 174.21.107.149 X-SA-Exim-Mail-From: david.ongaro@hamburg.de X-SA-Exim-Scanned: No (on longisland.ops.eusc.inter.net); SAEximRunCond expanded to false X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:180346 Archived-At: On 15.05.20, 03:19, "Mattias Engdeg=C3=A5rd" wrote: > Thank you for reporting this. It seems that Calc first simplifies gcd(0,n= ) to n and then computes sum(n,n,-1,-1) =3D -1. > We could either make gcd(0,x)=3Dgcd(x,0)=3D|x|, or try preventing sum from si= mplifying its operand first, or both. > For the smallest possible change, what about the hack below? I see, so the simplest reproduction of the bug doesn't involve the sum, but= just the evaluation of gcd(0, x) or gcd(x, 0). Your fix seems sensible to m= e, I don't see why you consider it a 'hack'. The simplification gcd(0, x)=3Dgc= d(x, 0)=3Dabs(x) seems legit and matches the gcd definition "The largest posit= ive integer that divides each of the integers".