From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17583 invoked from network); 17 Jun 2008 09:45:29 -0000 X-Spam-Checker-Version: SpamAssassin 3.2.4 (2008-01-01) on f.primenet.com.au X-Spam-Level: X-Spam-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.2.4 Received: from news.dotsrc.org (HELO a.mx.sunsite.dk) (130.225.247.88) by ns1.primenet.com.au with SMTP; 17 Jun 2008 09:45:29 -0000 Received-SPF: none (ns1.primenet.com.au: domain at sunsite.dk does not designate permitted sender hosts) Received: (qmail 31297 invoked from network); 17 Jun 2008 09:45:25 -0000 Received: from sunsite.dk (130.225.247.90) by a.mx.sunsite.dk with SMTP; 17 Jun 2008 09:45:25 -0000 Received: (qmail 16867 invoked by alias); 17 Jun 2008 09:45:22 -0000 Mailing-List: contact zsh-workers-help@sunsite.dk; run by ezmlm Precedence: bulk X-No-Archive: yes X-Seq: 25172 Received: (qmail 16855 invoked from network); 17 Jun 2008 09:45:22 -0000 Received: from bifrost.dotsrc.org (130.225.254.106) by sunsite.dk with SMTP; 17 Jun 2008 09:45:22 -0000 Received: from mail.o2.co.uk (yoda.london.02.net [82.132.130.151]) by bifrost.dotsrc.org (Postfix) with ESMTP id 5AC868028AC3 for ; Tue, 17 Jun 2008 11:45:13 +0200 (CEST) Received: from sc.homeunix.net (78.105.216.138) by mail.o2.co.uk (8.0.013.3) (authenticated as stephane.chazelas) id 4851DD9500BFD764; Tue, 17 Jun 2008 10:45:09 +0100 Received: from chazelas by sc.homeunix.net with local (Exim 4.69) (envelope-from ) id 1K8XkT-0001hi-LV; Tue, 17 Jun 2008 10:45:09 +0100 Date: Tue, 17 Jun 2008 10:45:09 +0100 From: Stephane Chazelas To: Richard Hartmann Cc: Peter Stephenson , Zsh hackers list Subject: Re: arithmetic operator precedence Message-ID: <20080617094509.GC5016@sc.homeunix.net> Mail-Followup-To: Richard Hartmann , Peter Stephenson , Zsh hackers list References: <20080612095723.GF5113@sc.homeunix.net> <20080616080726.GP10734@prunille.vinc17.org> <20080616144211.276fb0e3@pws-pc> <2d460de70806170219k12ff4cadn441b52c48bf8076f@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2d460de70806170219k12ff4cadn441b52c48bf8076f@mail.gmail.com> User-Agent: Mutt/1.5.16 (2007-09-19) X-Virus-Scanned: ClamAV 0.92.1/7494/Tue Jun 17 06:46:03 2008 on bifrost X-Virus-Status: Clean On Tue, Jun 17, 2008 at 11:19:40AM +0200, Richard Hartmann wrote: [...] > > That's an interesting point for C_PRECEDENCES since I was trying to get > > it behave as much as possible like Perl. What does anyone else think? > > Being unsure myself, I did some somewhat extensive research. The only > mathematically correct way of doing this is > > -3**2 = -9 > (-3)**2 = 9 [...] In which way is it more "mathematically" correct? Is that because -3² is -9? But ** is not ^, it's a binary operator whose shape reminds that of multiply, like a multiply++. And even then, POSIX's ^ in bc is handled as -3^2 = 9. It could be a good idea to ask ksh, POSIX/bc and perl authors for the rationale behind their choices. -- Stéphane