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Re: st: Mata not computing eigenvectors/values


From   Steven Samuels <sjsamuels@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Mata not computing eigenvectors/values
Date   Mon, 10 Jan 2011 10:15:07 -0500

-
Zachary's code works for me if I substitute "A" for "network" in the - symeigensytem()- command:

symeigensystem(A,eigenvector,eigenvalue)


Steve
Stata 11,1 OS X 10.5.8

On Jan 9, 2011, at 9:22 PM, Matthew J Baker wrote:

While I am not sure about why the symeigensystem command isn't working, the problem might have something to do with the "A" matrix being rank deficient. In any case, I find that the commands:

eigensystem(A,X=.,L=.)

and

lefteigensystem(A,Y=.,M=.)

both generate values for eigenvalues and eigenvectors for the aforementioned A matrix (collected in X and L, and Y and M, respectively).

Matt Baker

---- Original message ----
Date: Sun, 9 Jan 2011 17:45:19 -0500
From: owner-statalist@hsphsun2.harvard.edu (on behalf of Zachary Neal <zpneal@gmail.com>)
Subject: st: Mata not computing eigenvectors/values
To: statalist@hsphsun2.harvard.edu

Running the commands below, mata does not yield any eigenvectors or
eigenvalues.  Computing eigenvectors/values in stata using matrix
symeigen seems to work without a problem.  Any help would be
appreciated.

mata
A = (0,0,0,0,0,1,0,1,0,0,0,0,0 \ ///
   0,0,0,0,0,0,0,1,0,1,0,0,0 \ ///
   0,0,0,1,0,1,1,0,1,0,1,1,1 \ ///
   0,0,1,0,0,0,1,0,0,0,0,0,0 \ ///
   0,0,0,0,0,0,0,1,0,0,0,0,0 \ ///
   1,0,1,0,0,0,0,0,0,0,0,1,0 \ ///
   0,0,1,1,0,0,0,0,0,0,0,0,0 \ ///
   1,1,0,0,1,0,0,0,0,0,0,0,0 \ ///
   0,0,1,0,0,0,0,0,0,0,0,0,0 \ ///
   0,1,0,0,0,0,0,0,0,0,0,0,0 \ ///
   0,0,1,0,0,0,0,0,0,0,0,0,0 \ ///
   0,0,1,0,0,1,0,0,0,0,0,0,0 \ ///
   0,0,1,0,0,0,0,0,0,0,0,0,0)
eigenvector = 0
eigenvalue = 0
symeigensystem(network,eigenvector,eigenvalue)
eigenvector
eigenvalue
end

--
Zachary Neal, PhD
Department of Sociology
Michigan State University
zpneal@msu.edu
http://www.msu.edu/~zpneal
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