Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: What is the determinant of [] ? Date: Mon, 25 Oct 2010 18:17:04 +0000 (UTC) Organization: Xoran Technologies Lines: 10 Message-ID: <ia4hj0$3qk$1@fred.mathworks.com> References: <99996f6f-471e-49b6-9c95-a6ff3efed38b@j2g2000yqf.googlegroups.com> <ia3t2n$c7m$1@fred.mathworks.com> <ia43ko$sd3$1@fred.mathworks.com> <ia4bpb$jid$1@fred.mathworks.com> <ia4gfc$lj4$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: webapp-02-blr.mathworks.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1288030624 3924 172.30.248.37 (25 Oct 2010 18:17:04 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Mon, 25 Oct 2010 18:17:04 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1440443 Xref: news.mathworks.com comp.soft-sys.matlab:681193 "Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <ia4gfc$lj4$1@fred.mathworks.com>... > > > [1 []] is 1, this is perfectly clear as Sean explained. > > []*1 is [] because of the rule of scalar expansion. More generally, a (scalar * matrix) or the opposite return the result that has the same size as the matrix. In your example is 0x0, thus []. ======== The reasons/rules for what's observed are quite clear, but my point was, these rules are in conflict. You would think that prod([1 []]) ought to be the same as []*1, just as prod([1,2]) is the same as 1*2.