[SciPy-user] First few eigenvectors of a numarray array

David Grant david.grant at telus.net
Thu Sep 2 14:35:25 CDT 2004

When you say "top 10" do you mean the eigenvalues with the largest or 
smallest values?

I would also be interested in knowing if there is any mathematical way 
of doing this.  Sometimes for example in molecular simulations you only 
want to calculate the ground state energy, for example, and you don't 
care about the rest...


Stuart Murdock wrote:

> Hi
> I have a 10000 by 10000 square numarray array which I have obtained 
> using numarray. I need to obtain the first 10 eigenvalues and
> eigenvectors of this so I dont want to have to calculate all 
> eigenvectors of the matrix. Is anyone aware of any pythonic packages 
> which
> can calculate, lets say, the 10 eigenvectors corresponding to the top 
> 10 eigenvalues of a numarray array.
> There are a few functions which calculate all of the eigenvectors e.g.
> eig
> eigenvectors
> but I only want to calculate the top few.
> Thanks
> Stuart

David J. Grant

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