[R] matrix exponential: M^0

[Giovanni Petris]

elementary operations, like taking a power, act elementwise on vectors
and matrices. You may use a spectral decomposition to compute powers
of a matrix - or a for loop if you are interested in small integer
powers. 

HTH
Giovanni

-- 

 __________________________________________________
[                                                  ]
[ Giovanni Petris                 GPetris at uark.edu ]
[ Department of Mathematical Sciences              ]
[ University of Arkansas - Fayetteville, AR 72701  ]
[ Ph: (479) 575-6324, 575-8630 (fax)               ]
[ http://definetti.uark.edu/~gpetris/              ]
[__________________________________________________]

> Date: Tue, 20 Jan 2004 16:40:07 +0000
> From: Federico Calboli <f.calboli at ucl.ac.uk>
> Sender: r-help-bounces at stat.math.ethz.ch
> Organization: 
> Precedence: list
> 
> Dear All, 
> 
> I would like to ask why the zeroeth power of a matrix gives me a matrix
> of ones rather than the identity matrix:
> 
> > D<-rbind(c(0,0,0),c(0,0,0),c(0,0,0))
> > D<-as.matrix(D)
> > D
>      [,1] [,2] [,3]
> [1,]    0    0    0
> [2,]    0    0    0
> [3,]    0    0    0
> 
> > D^0
>      [,1] [,2] [,3]
> [1,]    1    1    1
> [2,]    1    1    1
> [3,]    1    1    1
> 
> I would have expected the identity matrix here.
> 
> I find the same result with every other square matrix I used.
> BTW, I am using R 1.8.1 on Linux Mandrake 9.1
> 
> Cheers,
> 
> Federico Calboli
> -- 
> 
> 
> 
> =================================
> 
> Federico C. F. Calboli
> 
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