[petsc-users] Incorrect eigenvalues

[Hassan Md Mahmudulla]

Thank you very much for your reply. Well, I actually can avoid using eps_interval since I don't really need that. I want to request 10% eigenvalues and I need them very fast. That's why I was trying with different combinations. My system size can be bigger. So, I was trying iterative solver like mumps as well. But the problem is almost all the preconditioners are giving me wrong answers. Would you suggest me any way so that I can solve my problem? I will try with section 3.4.5 though.


M Hassan



________________________________
From: Jose E. Roman <jroman at dsic.upv.es>
Sent: Monday, July 18, 2016 2:00:16 PM
To: Hassan Md Mahmudulla
Cc: petsc-users at mcs.anl.gov; slepc-maint at upv.es
Subject: Re: [petsc-users] Incorrect eigenvalues


> El 18 jul 2016, a las 21:48, Hassan Md Mahmudulla <mhassan at miners.utep.edu> escribió:
>
> Would you please give me an idea what combination of ksp solver and preconditioner I should use to solve this generalized symmetric hermitian problem? To get the convergence faster, do I need to use external solvers like mumps and superlu_dist?
>
> Thanks
> M Hassan

For computing eigenvalues in an interval, you have to follow exactly what is written in section 3.4.5 of SLEPc's users manual. It is not possible to use preconditioners in that case. Also, superlu_dist cannot be used for this, only MUMPS or PETSc's cholesky (sequential).

Jose

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20160718/d2bc4ea4/attachment.html>