[petsc-users] monitoring the convergence of fieldsplit 0 and 1

[Barry Smith]

> On Apr 10, 2015, at 8:07 AM, Klaij, Christiaan <C.Klaij at marin.nl> wrote:
> 
> Barry,
> 
> Sure, I can call PCFieldSplitGetSubKSP() to get the fieldsplit_0
> ksp and then KSPGetIterationNumber, but what does this number
> mean?
> 
> It appears to be the number of iterations of the last time that
> the subsystem was solved, right? If so, this corresponds to the
> last iteration of the coupled system, how about all the previous
> iterations?

   If I added a KSPGetTotalIterations() would that help?

Barry

> 
> Chris
> ________________________________________
> From: Barry Smith <bsmith at mcs.anl.gov>
> Sent: Friday, April 10, 2015 2:48 PM
> To: Klaij, Christiaan
> Cc: petsc-users at mcs.anl.gov
> Subject: Re: [petsc-users] monitoring the convergence of fieldsplit 0 and 1
> 
>   Chris,
> 
>     It appears you should call PCFieldSplitGetSubKSP() and then get the information you want out of the individual KSPs. If this doesn't work please let us know.
> 
>   Barry
> 
>> On Apr 10, 2015, at 6:48 AM, Klaij, Christiaan <C.Klaij at marin.nl> wrote:
>> 
>> A question when using PCFieldSplit: for each linear iteration of
>> the system, how many iterations for fielsplit 0 and 1?
>> 
>> One way to find out is to run with -ksp_monitor,
>> -fieldsplit_0_ksp_monitor and -fieldsplit_0_ksp_monitor. This
>> gives the complete convergence history.
>> 
>> Another way, suggested by Matt, is to use -ksp_monitor,
>> -fieldsplit_0_ksp_converged_reason and
>> -fieldsplit_1_ksp_converged_reason. This gives only the totals
>> for fieldsplit 0 and 1 (but without saying for which one).
>> 
>> Both ways require to somehow process the output, which is a bit
>> inconvenient. Could KSPGetResidualHistory perhaps return (some)
>> information on the subsystems' convergence for processing inside
>> the code?
>> 
>> Chris
>> 
>> 
>> dr. ir. Christiaan Klaij
>> CFD Researcher
>> Research & Development
>> E mailto:C.Klaij at marin.nl
>> T +31 317 49 33 44
>> 
>> 
>> MARIN
>> 2, Haagsteeg, P.O. Box 28, 6700 AA Wageningen, The Netherlands
>> T +31 317 49 39 11, F +31 317 49 32 45, I www.marin.nl
>> 
>