From: <HIDDEN>
Newsgroups: comp.soft-sys.matlab
Subject: Re: How to make the function 'norm' treat its input as vectors?
Date: Thu, 14 Oct 2010 18:47:03 +0000 (UTC)
Organization: Xoran Technologies
Lines: 10
Message-ID: <i97j77$9db$>
References: <i938ok$smb$> <i93kdo$o8f$> <i94def$3h4$> <i94mh3$9c3$> <i94v8c$r8p$> <i958vn$cjb$> <i95ak3$srq$> <i96neg$hsc$> <i96r2q$d0f$> <i96sss$c0c$> <i970h5$dlh$> <i979nj$arb$> <i97g3s$eij$> <i97imb$4cl$>
Reply-To: <HIDDEN>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
X-Trace: 1287082023 9643 (14 Oct 2010 18:47:03 GMT)
NNTP-Posting-Date: Thu, 14 Oct 2010 18:47:03 +0000 (UTC)
X-Newsreader: MATLAB Central Newsreader 1440443
Xref: comp.soft-sys.matlab:678524

"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <i97imb$4cl$>...
> "Matt J " <mattjacREMOVE@THISieee.spam> wrote in message <i97g3s$eij$>...
> > 
> > The speed of MTIMESX won't matter. If you take norms along anything but columns using mtimesx, you will need to first permute/transpose the data, 
> Is that true? Are you sure any explicit transposition is carried out? May be James can confirm it.

According to my best understanding of how MTIMESX works, yes. The partitioning of  an nD array into submatrices by mtimesx is always in memory-contiguous blocks. Since rows of a matrix are not contiguous, I don't see how you can get mtimesx(A,B) to do operations between corresponding rows of A and B.