From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Neon Absentius Newsgroups: gmane.emacs.help Subject: Re: Non-Commutative calculations in Calc, Revisited Date: Fri, 7 Oct 2005 02:15:53 +0000 Message-ID: <20051007021553.GE29712@SDF.LONESTAR.ORG> References: <878xx66b1c.fsf@vh213602.truman.edu> <851x2yu5gv.fsf@lola.goethe.zz> <20051006180113.GA24696@SDF.LONESTAR.ORG> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1128651433 29877 80.91.229.2 (7 Oct 2005 02:17:13 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Fri, 7 Oct 2005 02:17:13 +0000 (UTC) Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Oct 07 04:17:12 2005 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1ENhn0-000502-SF for geh-help-gnu-emacs@m.gmane.org; Fri, 07 Oct 2005 04:16:51 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ENhn0-0006TB-AG for geh-help-gnu-emacs@m.gmane.org; Thu, 06 Oct 2005 22:16:50 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1ENhmm-0006S5-Jz for help-gnu-emacs@gnu.org; Thu, 06 Oct 2005 22:16:36 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1ENhml-0006Qs-13 for help-gnu-emacs@gnu.org; Thu, 06 Oct 2005 22:16:36 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ENhmk-0006Qk-TY for help-gnu-emacs@gnu.org; Thu, 06 Oct 2005 22:16:34 -0400 Original-Received: from [192.94.73.21] (helo=sdf.lonestar.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1ENhmk-00007P-I9 for help-gnu-emacs@gnu.org; Thu, 06 Oct 2005 22:16:34 -0400 Original-Received: from sdf.lonestar.org (IDENT:absent@ukato.freeshell.org [192.94.73.7]) by sdf.lonestar.org (8.13.1/8.12.10) with ESMTP id j972FtkL025564 for ; Fri, 7 Oct 2005 02:15:56 GMT Original-Received: (from absent@localhost) by sdf.lonestar.org (8.13.1/8.12.8/Submit) id j972Frv9020590 for help-gnu-emacs@gnu.org; Fri, 7 Oct 2005 02:15:53 GMT Original-To: help-gnu-emacs@gnu.org Mail-Followup-To: Neon Absentius , help-gnu-emacs@gnu.org Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i 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:30011 Archived-At: On Thu, Oct 06, 2005 at 08:15:10PM -0500, Luc Teirlinck wrote: > In any case I do think that is a good idea to have a command > that assumes that all variables are square matrices or, in the > abstract language, that any two elements are composable. > > As I already pointed out in my follow-up, does `Meta-N m v' not do that? > (It assumes that all matrices are N by N square matrices.) > I am not sure whether my follow-up actually got posted, which is why I > am using email now. > Yes indeed assuming that all matrices are square matrices *of a given size* does solve the problem of "poor man's non-commutative mode". And there we can safely use the rule about the inverse of a product. Thanks for pointing this out and for taking the extra pain to email me about it so that I can take the message for sure! BTW my statement that you quoted as it stands it's not true: even if we assume that all matrices are square still we cannot necessarily compose them unless they have the same dimensions! Still it might be usefull to have an assmption that all variables are square matrices of *unspecified* dimension. PS. I reply in the group/list since it is not sure whether your post will eventually show up. > Sincerely, > > Luc. -- There is no national science just as there is no national multiplication table; what is national is no longer science. -- Anton Checov