From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Marco Almeida Newsgroups: gmane.emacs.help Subject: Re: lisp question Date: Tue, 01 May 2007 22:11:42 +0100 Message-ID: <877irs9rld.wl%mfa@ncc.up.pt> References: <31145455.103801178044797761.JavaMail.www@wwinf4203> <87tzuwe4wb.fsf@Jesper-Harders-Computer.local> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII X-Trace: sea.gmane.org 1178055565 30519 80.91.229.12 (1 May 2007 21:39:25 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 1 May 2007 21:39:25 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Tue May 01 23:39:24 2007 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1Hj04A-0007v7-8q for geh-help-gnu-emacs@m.gmane.org; Tue, 01 May 2007 23:39:22 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Hj0AU-0003aL-Su for geh-help-gnu-emacs@m.gmane.org; Tue, 01 May 2007 17:45:54 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Hj05O-0008Ky-Tt for help-gnu-emacs@gnu.org; Tue, 01 May 2007 17:40:38 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Hj05N-0008KT-CA for help-gnu-emacs@gnu.org; Tue, 01 May 2007 17:40:38 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Hj05N-0008KK-4B for help-gnu-emacs@gnu.org; Tue, 01 May 2007 17:40:37 -0400 Original-Received: from smtp4.netcabo.pt ([212.113.174.31] helo=exch01smtp12.hdi.tvcabo) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Hizz1-00012F-JG for help-gnu-emacs@gnu.org; Tue, 01 May 2007 17:34:03 -0400 Original-Received: from neti03mx.hdi.tvcabo ([10.137.34.35]) by exch01smtp12.hdi.tvcabo with Microsoft SMTPSVC(6.0.3790.1830); Tue, 1 May 2007 22:11:43 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Aj0KADtKN0bVFpJHQWdsb2JhbACBeY4lAQEBKQ Original-Received: from a213-22-146-71.cpe.netcabo.pt (HELO khosmo.mfa.kicks-ass.org) ([213.22.146.71]) by neti03smtp.hdi.tvcabo with ESMTP; 01 May 2007 22:11:43 +0100 In-Reply-To: <87tzuwe4wb.fsf@Jesper-Harders-Computer.local> User-Agent: Wanderlust/2.15.5 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (=?ISO-8859-4?Q?Shij=F2?=) APEL/10.7 Emacs/21.4 (powerpc-unknown-linux-gnu) MULE/5.0 (SAKAKI) X-OriginalArrivalTime: 01 May 2007 21:11:43.0810 (UTC) FILETIME=[51DF6A20:01C78C35] X-detected-kernel: Windows 2000 SP4, XP SP1+ X-Greylist: delayed 1332 seconds by postgrey-1.27 at monty-python; Tue, 01 May 2007 17:34:01 EDT X-Mailman-Approved-At: Tue, 01 May 2007 17:45:40 -0400 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:43461 Archived-At: At Tue, 01 May 2007 21:10:44 +0200, Jesper Harder wrote: > > A Soare writes: > > > What determined the mathematicians to give the definition of x^0 = 1, > > not defined for x=0 ? > > Because 0/0 is undefined: > > x^1 x > x^0 = ---- = --- > x^1 x > > x=0 -> 0/0. > As far as I know, 0^0 = 0 by convention (pretty much like 0 != 1) Also, I think that your argument is wrong. 0^y = 0 for any y 0 is the characteristic of R and you can not divid by it This means that your first step : x^1 x^0 = ---- x^1 is not valid, regardeless of the value you chose as exponent because you will be trying a division by zero. Also, from Concrete Mathematics p.162 (R. Graham, D. Knuth, O. Patashnik): Some textbooks leave the quantity 0^0 undefined, because the functions 0^x and x^0 have different limiting values when x decreases to 0. But this is a mistake. We must define x^0=1 for all x , if the binomial theorem is to be valid when x=0 , y=0 , and/or x=-y . The theorem is too important to be arbitrarily restricted! By contrast, the function 0^x is quite unimportant. > > > _______________________________________________ > help-gnu-emacs mailing list > help-gnu-emacs@gnu.org > http://lists.gnu.org/mailman/listinfo/help-gnu-emacs >