From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Kevin Ryde Newsgroups: gmane.lisp.guile.bugs Subject: Re: generic * and 0 Date: Tue, 05 Dec 2006 11:00:28 +1100 Message-ID: <87wt57ky8z.fsf@zip.com.au> References: <456DCA43.6030705@ludens.elte.hu> <878xhr4cgj.fsf@zip.com.au> <66e540fe0612011222n42a0e62ai1250ff67ae801c93@mail.gmail.com> <87irgv2sj6.fsf@zip.com.au> <87zma433s7.fsf@zip.com.au> <66e540fe0612041026n3a6ca3f5ye46e775becdce611@mail.gmail.com> NNTP-Posting-Host: dough.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1165276903 13657 80.91.229.10 (5 Dec 2006 00:01:43 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 5 Dec 2006 00:01:43 +0000 (UTC) Original-X-From: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Tue Dec 05 01:01:41 2006 Return-path: Envelope-to: guile-bugs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by dough.gmane.org with esmtp (Exim 4.50) id 1GrNkh-00066U-IZ for guile-bugs@m.gmane.org; Tue, 05 Dec 2006 01:01:39 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GrNkh-000484-8X for guile-bugs@m.gmane.org; Mon, 04 Dec 2006 19:01:39 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1GrNjo-0003pU-5U for bug-guile@gnu.org; Mon, 04 Dec 2006 19:00:44 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1GrNjm-0003oc-7b for bug-guile@gnu.org; Mon, 04 Dec 2006 19:00:43 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GrNjm-0003oV-28 for bug-guile@gnu.org; Mon, 04 Dec 2006 19:00:42 -0500 Original-Received: from [61.8.2.215] (helo=mailout1.pacific.net.au) by monty-python.gnu.org with esmtp (Exim 4.52) id 1GrNjl-0007GG-BQ for bug-guile@gnu.org; Mon, 04 Dec 2006 19:00:41 -0500 Original-Received: from mailproxy1.pacific.net.au (mailproxy1.pacific.net.au [61.8.2.162]) by mailout1.pacific.net.au (Postfix) with ESMTP id 8B6F95A0C1D for ; Tue, 5 Dec 2006 11:00:34 +1100 (EST) Original-Received: from localhost (ppp2E12.dyn.pacific.net.au [61.8.46.18]) by mailproxy1.pacific.net.au (Postfix) with ESMTP id E55138C2F for ; Tue, 5 Dec 2006 11:00:33 +1100 (EST) Original-Received: from gg by localhost with local (Exim 4.63) (envelope-from ) id 1GrNjZ-0002xT-CD for bug-guile@gnu.org; Tue, 05 Dec 2006 11:00:29 +1100 Original-To: bug-guile@gnu.org In-Reply-To: <66e540fe0612041026n3a6ca3f5ye46e775becdce611@mail.gmail.com> (Mikael Djurfeldt's message of "Mon, 4 Dec 2006 19:26:12 +0100") User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) X-BeenThere: bug-guile@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Bug reports for GUILE, GNU's Ubiquitous Extension Language" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Errors-To: bug-guile-bounces+guile-bugs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.bugs:3413 Archived-At: "Mikael Djurfeldt" writes: > > Good idea. I made the change. > Because of paragraph 6.2.2, a program cannot expect to get > the result 0.0, and it seems like a strength of the implementation to > provide the additional piece of information that the result is indeed > *exactly* 0. If you wanted an argument the other way, returning a flonum zero could give negative zero for say "(* 0 -1.0)". But I'd favour exactness, since the result is certainly exactly zero. > (Not entirely sure that the common zero is a good idea, but I tend > to think so.) I suppose it's a question of whether "*" should do that, or leave it up to the application. The only case I can think of where a common zero may not be good is with matrices, where "(* 0 matrix) => matrix" could preserve the dimensions of the input matrix in the output matrix. Those dimensions could be used later "(* matrix matrix)", to signal an error if the dimensions were incompatible. _______________________________________________ Bug-guile mailing list Bug-guile@gnu.org http://lists.gnu.org/mailman/listinfo/bug-guile