From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Jay Belanger Newsgroups: gmane.emacs.help Subject: Re: Bug in Calc? Date: Wed, 07 Sep 2005 08:56:37 -0500 Organization: Posted via Supernews, http://www.supernews.com Message-ID: <87r7c1f0bu.fsf@vh213602.truman.edu> References: <87hdcydkvh.fsf@vh213602.truman.edu> <20050906213348.GE12694@SDF.LONESTAR.ORG> Reply-To: belanger@truman.edu NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1126101890 15790 80.91.229.2 (7 Sep 2005 14:04:50 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Wed, 7 Sep 2005 14:04:50 +0000 (UTC) Cc: belanger@truman.edu Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Sep 07 16:04:47 2005 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1ED0Ut-0007HK-VP for geh-help-gnu-emacs@m.gmane.org; Wed, 07 Sep 2005 16:01:56 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ED0ZR-0005RS-OK for geh-help-gnu-emacs@m.gmane.org; Wed, 07 Sep 2005 10:06:37 -0400 Original-Path: shelby.stanford.edu!newsfeed.stanford.edu!newsfeed.gamma.ru!Gamma.RU!demos!news.rssi.ru!mtu.ru!sn-xit-04!sn-xit-10!sn-xit-06!sn-post-01!supernews.com!corp.supernews.com!not-for-mail Original-Newsgroups: gnu.emacs.help User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux) Cancel-Lock: sha1:x2wrAvA2ueNY+YLInRqsoYP69/g= Original-X-Complaints-To: abuse@supernews.com Original-Lines: 26 Original-Xref: shelby.stanford.edu gnu.emacs.help:133751 Original-To: help-gnu-emacs@gnu.org X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:29296 Archived-At: Neon Absentius writes: > On Tue, Sep 06, 2005 at 09:33:48PM +0000, Neon Absentius wrote: > >> there seems to be a bug: After I give 'm v' if I ask calc to >> simplify the expression 'a b - b a' it leaves it as is which is as >> expected. However when I ask it to expand '(a+b)^2' it returns >> 'a^2 + 2 b a + b^2' which is of course wrong if a and b don't commute. >> This happens both with emacs-multi-tty (22.0.50) and whith emacs >> 21.4.1 on a Debian testing/unstable. The bug manifsts itself also >> for the expansion of '(a+b)^3' however calc expands '(x+y)(x-y)' >> into 'x^2 + y x - x y + y^2'. Strange! > > Maybe not so strange. Maybe not strange, but still a bug. > Probably calc uses formulae (the binomial expansion?) to expand the > power instead of fully distributing the multiplication over the > addtition "by hand", so to speak. Of course the binomial expansion > is not valid if the variables involved do not commute. That is what happens. It should be fixed soon. Jay