[R] Beginning Eigen System question.

[Joris Meys]

On Thu, Jun 24, 2010 at 12:41 AM, Joris Meys <jorismeys at gmail.com> wrote:
> Which other Linear Algebra system, and which function did you use in R?
> Cheers
> Joris

Never mind, off course you used "eigen()"...
Eigenvectors are only determined up to a constant. If I'm not mistaken
(but check the help files on it), R normalizes the eigenvectors (and
so does your other Linear Algebra system). This makes the eigenvectors
 defined up to the sign.

Cheers
Joris
>
> On Thu, Jun 24, 2010 at 12:32 AM,  <rkevinburton at charter.net> wrote:
>> Forgive me if I missunderstand a basic Eigensystem but when I present the following matrix to most any other LinearAlgebra system:
>>
>>  1  3  1
>>  1  2  2
>>  1  1  3
>>
>> I get an answer like:
>>
>> //$values
>> //[1]  5.000000e+00  1.000000e+00 -5.536207e-16
>>
>> //$vectors
>> //           [,1]       [,2]       [,3]
>> //[1,] 0.5773503 -0.8451543 -0.9428090
>> //[2,] 0.5773503 -0.1690309  0.2357023
>> //[3,] 0.5773503  0.5070926  0.2357023
>>
>> But R gives me:
>>
>> //$values
>> //[1]  5.000000e+00  1.000000e+00 -5.536207e-16
>>
>> //$vectors
>> //           [,1]       [,2]       [,3]
>> //[1,] -0.5773503 -0.8451543 -0.9428090
>> //[2,] -0.5773503 -0.1690309  0.2357023
>> //[3,] -0.5773503  0.5070926  0.2357023
>>
>> The only difference seems to be the sign on the first eigen vector. What am I missing?
>>
>> Kevin
>>
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Joris Meys
> Statistical consultant
>
> Ghent University
> Faculty of Bioscience Engineering
> Department of Applied mathematics, biometrics and process control
>
> tel : +32 9 264 59 87
> Joris.Meys at Ugent.be
> -------------------------------
> Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
>



-- 
Joris Meys
Statistical consultant

Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

tel : +32 9 264 59 87
Joris.Meys at Ugent.be
-------------------------------
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php