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

[Klaij, Christiaan]

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?

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
>