what's the difference between dsyev/x/r/d?

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what's the difference between dsyev/x/r/d?

Postby bsmile » Sat Dec 04, 2010 2:44 pm

and what are their performance difference?

Thanks,
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Re: what's the difference between dsyev/x/r/d?

Postby admin » Fri Dec 17, 2010 3:42 pm

Here is the difference:
- eigenvalues only: SYEV
- eigenvectors and eigenvalues:
* subset computation: SYEVR or SYEVX
* all eigenvectors: SYEVD or SYEVR or SYEVX

Which one is faster depends on the matrices.

See, for example:
http://www.netlib.org/lapack/lawnspdf/lawn182.pdf
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