eigh: eigenvalue order

Nils Wagner nwagner at iam.uni-stuttgart.de
Tue Oct 24 13:26:30 CDT 2006


On Tue, 24 Oct 2006 11:16:19 -0700
  "Keith Goodman" <kwgoodman at gmail.com> wrote:
> Is there any guarantee on the order of eigenvalues (and 
>eigenvectors)
> returned by numpy.linalg.eigh?
> 
> If I want to make sure the eigenvalues are in ascending 
>order of
> magnitude should I sort them myself?
> 
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AFAIK eigh is based on dsyevd.f
http://www.netlib.org/lapack/double/dsyevd.f. (real 
symmetric)
http://www.netlib.org/lapack/complex16/zheevd.f (complex 
Hermitian).
If INFO = 0, the eigenvalues are given in ascending order.

Please correct me if I get it wrong.

Nils

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