[Numpy-discussion] higher accuracy in diagonialzation

Daπid davidmenhur at gmail.com
Mon Oct 27 07:55:05 EDT 2014


On 27 October 2014 09:37, Sunghwan Choi <sunghwanchoi91 at gmail.com> wrote:

> One of them is inaccurate or both two of them are inaccurate within that
> range. Which one is more accurate?


You can check it yourself using the eigenvectors. The cosine distance
between v and M.dot(v) will give you the error in the eigenvectors, and the
difference between ||lambda*v|| and ||M.dot(v)|| the error in the
eigenvalue. I would also check the condition numbers, maybe your matrix is
just not well conditioned. You would have to look at preconditioners.


/David.
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