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Topic: how to compute length of principal axis
Replies: 6   Last Post: Oct 31, 2011 6:04 PM

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R Kym Horsell

Posts: 339
Registered: 12/13/04
Re: how to compute length of principal axis
Posted: Oct 31, 2011 6:04 PM
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In sci.math MBALOVER <> wrote:
> thanks but no equation for computing length of the major axis.

It could be as simple as 2/lambda_1^2 where lambda_1 is the smallest eigenvalue.
Depends on what you can easily do or have done to your data first in the way
of centering and normalising. You can sometimes forget the normalising and use
the sum of the eigenvalues (that may or may not be the same as the Tr of the
original matrix, depending on application area) as a final scale factor.
Usual lawyer talk if not all eigenvalues are real and positive.

> Kooks don't accept evaporation without a book reference? ROTFLOL!
Huh? I can't find your cite ....
-- BONZO@27-32-240-172 [daily nymshifter], 14 Oct 2011 11:56 +1100

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