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Re: mpower
From: |
Joe Koski |
Subject: |
Re: mpower |
Date: |
Wed, 27 Sep 2006 20:44:51 -0600 |
User-agent: |
Microsoft-Entourage/11.2.5.060620 |
on 9/27/06 8:38 PM, John W. Eaton at address@hidden wrote:
> On 27-Sep-2006, Eric and Diana Luft wrote:
>
> | Is there any Octave equivalent to the matlab "mpower" command, which would
> compute a matrix to an arbitrary, eg fractional, power? I want to compute a
> matrix to the 2/3 power, but I get a complex-valued matrix as a result, where
> it should be real-valued. Details follow below, where A2 comes out to be
> complex-valued when I think it should be real-valued:
> |
> | M=[1 1 1; 1 2 2; 1 2 3]
> |
> | K=[2 -1 .5;-1 1.2 .4;.5 .4 1.8]
> |
> | A2=logm(inv(M)*K)^(2/3)
>
> Why do you think it should be real valued? What are you trying to
> compute, the matrix to a fracional power, or the elements to a
> fractional power? When you write the above expression, are you
> expecting the matrix (or elements) to be squared first, followed by a
> cube-root function? That is not what you have written.
>
> | Thanks for any help or advice,
>
> Searching for mpower here:
>
> http://www.mathworks.com/access/helpdesk/help/techdoc/matlab.html
>
> says that mpower is not a Matlab function. So where did you find
> mpower? Is it part of some external toolbox? If so, which one?
> Where is the documentation for it?
>
> jwe
>
John, Eric,
I found MATLAB mpower on the webpage
http://www.mathworks.com/access/helpdesk/help/toolbox/simulink/slref/index.h
tml?/access/helpdesk/help/toolbox/simulink/slref/bqthivm-12.html
It says that it is "Equivalent of array power operator (.^)"
Joe
- mpower, Eric and Diana Luft, 2006/09/27
- mpower, John W. Eaton, 2006/09/27