[petsc-users] SLEPc eigensolver that uses minimal memory and finds ALL eigenvalues of a real symmetric sparse matrix in reasonable time

[Jed Brown]

On Thu, Aug 11, 2011 at 02:23, Shitij Bhargava <shitij.cse at gmail.com> wrote:

> On eight CPUs, as it turns out, it will not take as long as I imagined. For
> a 9600x9600 matrix, to solve for half the largest eigenvalues, it took about
> 300 minutes. Although it would have taken much more time than this for
> solving half the smallest eigenvalues (I had to kill it at total time of 600
> minutes). This is still much much longer than the LAPACK method, which takes
> (for calculating all the eigenvalues at once) about 90 minutes (at the cost
> of much memory, which cant even be distributed -- which is unacceptable.


You should try Elemental for distributed-memory dense eigensolvers.

http://code.google.com/p/elemental/


> Also, I suppose you probably didnt know that I have to calculate ALL the
> eigenvalues).


Why do you need all of them? What underlying problem are you solving?
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