[petsc-users] Problem with TS and PCMG

[Jed Brown]

Torquil Macdonald Sørensen <torquil at gmail.com> writes:

> Just a second try in case the first email was unintentionally missed. 

I've been offline for the past few days.  I'll be back for real on Friday.

> In short, I'm wondering if it is possible to use TSSolve without using
> any DM structure:
>
> When I was debugging my program I tried to analyse the difference between
> the TSSolve-based time iteration program, and a version where I do the
> time-stepping manually using a for-loop which repeateed KSPSolve functions.
> The debugger showed that in the TSSolve program a pointer named
> ts->snes->ksp->pc->dm was nonzero, but in the for-loop program it was zero.
> In the TSSolve-program, and pc->dm != 0 made it enter a block of code
> within PCSetUp_MG that called DMCoarsen, which then crashed. So I guess I'm
> wondering how to tell PETSc that I'm not using any DM structure.

Please show the entire trace.  Callback pointers are stored on an
"internal" DM if you don't provide one.  This is important for nonlinear
preconditioning and other types of composition.  What preconditioner are
you intending to use?
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