[petsc-users] Delfated Krylov solver in PETSc

Qin Lu lu_qin_2000 at yahoo.com
Thu Feb 13 15:04:49 CST 2014

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?

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:


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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