| Re: [eigen] Help Eigen - eigenvalues and eigenvectors |
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On 21.01.2014 11:59, Nicolas BOUSSONNIERE wrote:
Results (values D and vectors V for matrice A) between the two executions
(with -O2 first and with -g second) are differents (and with a big
difference for eigenvectors) !
Do you have eigenvalues which occur multiple times are very close? Then
any linear combination of the corresponding eigenvectors is also a valid
eigenvector, and Eigen might choose a different due to small numerical
differences. Another possibility is that an eigenvector is only
different by sign.
Furthermore, the order of the eigenvalues is not guaranteed by
EigenSolver, so you might want to sort them anyways.
I don't know which is the best result because all seems good :
A = V D V-1
and || V || = 1
Do you expect anything more from the result?
Christoph
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Dipl.-Inf., Dipl.-Math. Christoph Hertzberg
Cartesium 0.049
Universität Bremen
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