[petsc-users] Using Petsc with multiple RHS

[Barry Smith]

   Alexander,

    Do you expect that solving with a sparse right hand side will result in an answer that is also sparse? Normally once you've done the lower triangular solve and then the upper triangular solve won't the result be dense?

    Barry

On Dec 12, 2011, at 3:10 AM, Alexander Grayver wrote:

> Hi Barry,
> 
> Thanks for answer. I should have asked about that from the very beginning actually.
> I get 2 times decrease in performance with 20 RHS, I can imagine how slow it will be when I will use thousands of them,
> moreover it will require a lot of memory to store them as a dense matrix.
> 
> On 11.12.2011 18:50, Barry Smith wrote:
>> On Dec 11, 2011, at 9:29 AM, Alexander Grayver wrote:
>>    One by one
> 
> I'm wondering why? All main direct packages like MUMPS, SuperLU_DIST, PaSTiX support multiple RHS.
> 
>>    We do not handle a sparse right hand side.
> 
> Since I already transferred my code to PETSc anyway, my question now if it's possible to implement sparse multiple RHS and solve them simultaneously?
> Something like MatMatSolveSparse. I would implement it myself, the question is there a way to integrate it into PETSc as a patch or something like that?
> 
> Regards,
> Alexander