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# Re: st: Mata not computing eigenvectors/values

 From Zachary Neal <[email protected]> To [email protected] Subject Re: st: Mata not computing eigenvectors/values Date Mon, 10 Jan 2011 13:39:41 -0500

```Sorry, that was a careless typo in my original message.  Steven is

symeigensystem(A,eigenvector,eigenvalue)

However, even with that correction, the outputs - eigenvector and
eigenvalue - are empty.

In contrast, if I attempt the same thing in stata, using:
matrix 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)
matrix symeigen eigenvectors eigenvalues = A
matrix list eigenvectors
matrix list eigenvalues

I am able to get the correct eigenvectors/values.

I'm still not sure why this seems to work in stata, but not in mata.

On Mon, Jan 10, 2011 at 10:15 AM, Steven Samuels <[email protected]> wrote:
> -
> 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: [email protected] (on behalf of Zachary Neal
>> <[email protected]>)
>> Subject: st: Mata not computing eigenvectors/values
>> To: [email protected]
>>
>> 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
>> [email protected]
>> http://www.msu.edu/~zpneal
>> *
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>> *   http://www.ats.ucla.edu/stat/stata/
>
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>

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

*
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*   http://www.ats.ucla.edu/stat/stata/
```