Thank you very much Peter,

Indeed this should be left to the reader/practitioner. But I think -at
least for the sake of comparison with matlab- we could have it in the core
R. I would definitely try to learn more about R and implement it later.

Cheers,
Ebrahim


On Sun, Mar 11, 2012 at 11:56 PM, Peter Langfelder <
peter.langfelder@gmail.com> wrote:

> On Sun, Mar 11, 2012 at 1:46 AM, Ebrahim Jahanshiri
> <e.jahanshiri@gmail.com> wrote:
> > Dear list,
> >
> > I understand that to raise matrix A to power (-1/2) we should use
> something
> > like this:
> >
> > eigen(A)$vectors%*%diag(1/sqrt(eigen(A)$values))%*%t(eigen(A)$vectors)
> >
> > [from previous discussions:
> > http://r.789695.n4.nabble.com/matrix-power-td900335.html]
> >
> > But this will only do it for negative sqrt of the matrix not for other
> > fraction powers like (-3/2).
>
> Not sure why you think this won't work for -3/2 - simply use
> eigen(A)$values^(-3/2) instead of the 1/sqrt(eigen(A)$values) and
> you're good to go. Generalizations to other powers are left as
> exercise for the reader :)
>
> Peter
>



-- 
Ebrahim Jahanshiri
Spatial and Numerical lab
ITMA
Universiti Putra Malaysia
43300, Selangor,
Malaysia
+60172002427
e.jahanshiri@gmail.com




-- 
Ebrahim Jahanshiri
Spatial and Numerical lab
ITMA
Universiti Putra Malaysia
43300, Selangor,
Malaysia
+60172002427
e.jahanshiri@gmail.com

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