[petsc-users] Spatial distribution of the residual after an implicit TS timestep

[Matthew Knepley]

On Sat, Mar 15, 2014 at 6:24 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>
>    You can write a custom monitor and set it with TSMonitorSet()
>
>     This routine would call TSGetSNES() then SNESGetSolution() then call
> SNESComputeFunction() then call VecView() on the result.
>
>     But note that just because the residual is big somewhere doesn't mean
> the error need be.
>
>     You could also run with -snes_monitor_residual to see how the residual
> is being reduced inside the nonlinear solve (that is, what parts of the
> residual are most stubborn).


If you really want to play with the residual, inside your monitor you can
use:

  TSGetSNES()

http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/SNES/SNESGetFunction.html#SNESGetFunction

  Thanks,

     Matt


>
>     Barry
>
>
> On Mar 15, 2014, at 5:47 PM, Mani Chandra <mc0710 at gmail.com> wrote:
>
> > Hi,
> >
> > Is there anyway I can VecView the residual after TS has completed an
> implicit time step? I'd like to see where in my domain most of the errors
> are coming from. I looked at TSMonitor but that doesn't seem to give me
> access to the residual at the end of the current time step.
> >
> > Thanks,
> > Mani
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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