DGMRES gone?

Open discussion for MAGMA library (Matrix Algebra on GPU and Multicore Architectures)
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JosefWeinbub
Posts: 4
Joined: Tue Aug 05, 2014 10:22 am

DGMRES gone?

Post by JosefWeinbub » Mon Jul 13, 2015 1:10 pm

Hi,
Just to verify: In 1.6.2 dgmres is gone? The declaration is there (sparse-iter/include/magmasparse_d.h) but the implementation is gone.
There is a 'dfgmres' version, is this one replacing dgmres or will dgmres come back in a future release?
Best, Josef

hartwig anzt
Posts: 90
Joined: Tue Sep 02, 2014 5:44 pm

Re: DGMRES gone?

Post by hartwig anzt » Mon Jul 13, 2015 3:58 pm

Dear Josef,

you are right, dgmres is still listed in the header, but does no longer exist. dfgmres is a flexible GMRES implementation, this allows for changing preconditioners. If you want a plain (unpreconditioned) GMRES, using dfgmres without preconditioner is almost equivalent. The performance differences are also negligible, as the cost of the additional copy in every iteration is small compared to the SpMV and the orthogonalization.
The purpose of removing was keeping the maintenance effort low. If you however need the original GMRES according to Saad's book, please let me know, and we will put it back in the next release.

Thanks, Hartwig

JosefWeinbub
Posts: 4
Joined: Tue Aug 05, 2014 10:22 am

Re: DGMRES gone?

Post by JosefWeinbub » Tue Jul 14, 2015 5:01 am

Hi Hartwig!

Thank you very much for your quick reply.
1.6.1 still has the GMRES implementation, that serves the purpose.

Best, Josef

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