R help - Apr 2012 - find the eigenvector corresponding to the largest eigenvalue

Hi,
If I use the eigen() function to find the eigenvalues of a matrix, how can I
find the eigenvector corresponding to the largest eigen value?
Thanks!
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On 27-04-2012, at 17:41, Rebecca wrote:
> Hi,
> If I use the eigen() function to find the eigenvalues of a matrix, how can
I find the eigenvector corresponding to the largest eigen value?

What does the documentation of eigen() say in the Value section for values?

Sorted in decreasing order.
So the first item of ..$values is the largest eigenvalue and thus the first
column of ..$vectors is the corresponding eigenvector.

Example

n <- 3
A  <- matrix(round(runif(n*n),2),nrow=n)
A
evv.A <- eigen(A)
evv.A

k <- which(abs(evv.A$values)==max(abs(evv.A$values)))
evv.A$vectors[,k]
k

Berend

On Apr 27, 2012, at 11:41 AM, Rebecca wrote:
> Hi,
> If I use the eigen() function to find the eigenvalues of a matrix,  
> how can I find the eigenvector corresponding to the largest eigen  
> value?
After reading the help page, I would have assumed that since the  
eigenvalues are sorted, that the eigenvectors would be sorted in the  
same order. Do you have reasons to doubt that they are not?

-- 

David Winsemius, MD
West Hartford, CT