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Subject: Re: How to make the function 'norm' treat its input as vectors?
Date: Thu, 14 Oct 2010 18:47:03 +0000 (UTC)
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"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <i97imb$4cl$1@fred.mathworks.com>...
> "Matt J " <mattjacREMOVE@THISieee.spam> wrote in message <i97g3s$eij$1@fred.mathworks.com>...
> 
> > 
> > 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.