[petsc-users] Delfated Krylov solver in PETSc

[Qin Lu]

Jed,
 
It seems there is a deflated GMRES solver in PETSc (KSPDGMRES), but PETSc manual does not give any details how to use it. A doc I found online is "parallel implementation of the deflated GMRES in the PETSc package", which mentioned to set number of eigenvalues to deflate by --ksp_dgmres_eigen, etc. Can I set these parameters by function calls (rather than using .petscrc)? 
 
Suppose the number of unknowns is 10,000, what would be the good number of number of eigenvalues to deflate? Or I may just use the default values (if they exist) for this solver?
 
Thanks,
Qin



On Thursday, February 13, 2014 1:07 PM, Jed Brown <jed at jedbrown.org> wrote:
  
Qin Lu <lu_qin_2000 at yahoo.com> writes:

> Hello,
>
> Is there a deflated Krylov solver available in PETSc? 

See the discussion here:

http://lists.mcs.anl.gov/pipermail/petsc-dev/2013-March/011393.html

Let us know if you have any follow-up questions.


> If yes, what is the corresponding solver name when calling KSPSetType?
> Does it work with any existing preconditioners?
>
> Many thanks for your info!
>
> Regards, Qin   
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