[Dune] Applying an ISTL InverseOperator to multiple right-hand sides

[Bernd Flemisch]

On 05/04/2010 11:18 AM, Bård Skaflestad wrote:
> Hi Markus,
>
> On Tue, 2010-05-04 at 10:45 +0200, Markus Blatt wrote:
>   
>> Hi,
>>
>> On Mon, May 03, 2010 at 05:52:58PM +0200, Bård Skaflestad wrote:
>>     
>>>       
>>>> Hi Bård!
>>>>
>>>> Assembling the matrix once and then solving for all rhs at once (e.g.
>>>> with a BCRSMatrix<ScaledIdMatrix>) may(!) still be faster, because you
>>>> get a better cache usage.
>>>>         
>>> Hi Oliver,
>>>
>>> The ScaledIdentityMatrix is indeed a possible solution.  I'll
>>> investigate its performance characteristics in my case.  
>>>       
>> While AMG compiles if SuperLU is deactivated, not using a direct solver
>>  on the coarse level might present a problem concerning convergence.
>>     
> Indeed.  When I started to use Dune I initially tried using the AMG
> preconditioner without a direct solver on the coarse level.  Let's just
> say that the overall convergence in some cases was...underwhelming ;-) 
> Adding SuperLU to the mix was a real performance booster.
>
>   
>> Therefore one should consider the time to adapt SuperLU to the matrix
>>  type.
>>     
> I'll leave that endeavour in your capable hands, but I just wanted to
> ask if there is a specific reason you don't support, e.g., UMFPACK as a
> coarse-level solver.  I consider "no time" a valid reason, by the way.
>   
The Pardiso direct solver basically accepts multiple right hand sides.
There is an interface included in dune-istl (which is maybe outdated, I
did not check for a long time), and one could try to adapt it to use
that multiple rhs feature. However, Pardiso has an inconvenient
licensing policy, each license is bound to user and host name. So for
sure not the most open source choice.

Kind regards
Bernd

>
> Cheers,
>
> Bård
>
>
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>   

-- 
_____________________________________________________________________

Bernd Flemisch                               phone: +49 711 685 69162
IWS, Universität Stuttgart                   fax:   +49 711 685 60430
Pfaffenwaldring 61                  email: bernd at iws.uni-stuttgart.de
D-70569 Stuttgart                  url: www.hydrosys.uni-stuttgart.de
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