Hi Thanks

Very simply one of the solutions for the zero eigenvalue is the 1 eigenvector.  
 If I get back this 1 vector, for the 0 eigenvalue then the other eigenvectors 
will be in the right format I am looking for. Once again, the 1 vector is the 
normalized eigenvector * norm.

Best
Louis Petingi

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________________________________
From: Robert Kern <robert.k...@gmail.com>
Sent: Saturday, February 25, 2023 2:28:45 PM
To: Discussion of Numerical Python <numpy-discussion@python.org>
Subject: [Numpy-discussion] Re: non normalised eigenvectors

On Sat, Feb 25, 2023 at 2:11 PM Louis Petingi 
<louis.peti...@csi.cuny.edu<mailto:louis.peti...@csi.cuny.edu>> wrote:
Thank you for the reply. I am working with the Laplacian matrix of a graph 
which is the Degree matrix minus the adjacency matrix.
The Laplacian is a symmetric matrix and the smallest eigenvalue is zero. As the 
rows add it to 0, Lx=0x, and 1 is the resulting vector. The normalized 
eigenvector is the 1 vector divided by the norm. So if a have 10 vertices of 
the graph the normalized eigenvector is 1/sqrt(10). I do understand that a 
scale * normalized eigenvector is also a solution but for the purpose of my 
research I need the normalized eigenvector * norm.

I apologize, but I'm going to harp on this: you are using the word "the" as if 
there is one unique magnitude that we could report. There is none. If you have 
a use for a specific convention for the magnitudes, you'll have to point us to 
the literature that talks about it, and we might be able to give you pointers 
as to how to get the magnitudes that your research requires.

For the 0 eigenvalue the norm of the eigenvector is easy to figure out but not 
for the other eigenvalues.

That is what I meant by the original eigenvector and sorry for the confusion 
the confusion. Most eigenvalues/eigenvalues calculators will give you 1 for 
first eigenvector

I'm afraid that doesn't really narrow anything down for us.

--
Robert Kern
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