[petsc-dev] [petsc-users] MATNEST with shell matrices

[Vijay S. Mahadevan]

Amneet, are you witnessing these errors in parallel alone, by any chance ?

The reason I ask is because one of the tests using VecNest (with
Get/Set SubVec = vec/examples/tests/ex41.c) fails in parallel and I
have a patch to fix this (attached). The primary issue is that calls
to SetSubVec create a mismatch in numbering of the IS maintained by
the VecNest structure which gets propagated by VecDuplicate. This only
happens in parallel though because the local numbering of the IS is
what gets modified wrongly. It might be a separate unrelated issue to
yours but cannot confirm for sure.

Jed can you please review this patch. If it works, feel free to push
after testing on ex41.c. I also have a variation of ex41 that is a
little more rigorous but I can send that to you in a separate patch.

Vijay

On Fri, Mar 1, 2013 at 5:05 PM, Amneet Bhalla <mail2amneet at gmail.com> wrote:
> Jed this is output from gdb:
>
> #0  0x0000000000000000 in ?? ()
> #1  0x00000000009857fd in VecGetArrayRead (x=0x33ba0b0, a=0x7fff1f0cf100) at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/include/petsc-private/vecimpl.h:350
> #2  0x000000000098f67f in VecGetArray_Nest (X=0x33c0850, x=0x7fff1f0cf200)
> at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/src/vec/vec/impls/nest/vecnest.c:719
> #3  0x0000000000a3f4df in VecGetArrayRead (x=0x33c0850, a=0x7fff1f0cf200) at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/include/petsc-private/vecimpl.h:350
> #4  0x0000000000a51d83 in MatMult (mat=0x326e480, x=0x33150c0, y=0x33c0850)
> at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/src/mat/interface/matrix.c:2092
> #5  0x00000000012b2b78 in KSPInitialResidual (ksp=0x32f6bb0,
> vsoln=0x33150c0, vt1=0x33c0850, vt2=0x33d3c60, vres=0x33e6d30, vb=0x3328710)
> at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/src/ksp/ksp/interface/itres.c:54
> #6  0x0000000000da2faa in KSPSolve_GMRES (ksp=0x32f6bb0) at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/src/ksp/ksp/impls/gmres/gmres.c:230
> #7  0x0000000000d1ae6b in KSPSolve (ksp=0x32f6bb0, b=0x3328710, x=0x33150c0)
> at
> /home/amneet/SOFTWARES/LIBRARIESIBAMR/PETSc-3.3-Lite/src/ksp/ksp/interface/itfunc.c:446
> #8  0x00000000006b8b0a in IBTK::PETScBlockKrylovLinearSolver::solveSystem
> (this=0x31f4310, x=0x329ed20, b=0x32b75d0) at
> PETScBlockKrylovLinearSolver.C:381
> #9  0x00000000005777e3 in main (argc=5, argv=0x7fff1f0d3468) at main.C:274
>
> In frame 5, there is call to function
>  PetscErrorCode  KSPInitialResidual(KSP ksp,Vec vsoln,Vec vt1,Vec vt2,Vec
> vres,Vec vb)
>
> which calls the matrix-vector function in frame 4, i.e,
> ierr = KSP_MatMult(ksp,Amat,vsoln,vt1);CHKERRQ(ierr);
>
> Now the error comes in frame 4, where there is call to
> VecValidValues(y,3,PETSC_FALSE); y being vt1, a temporary left Vec to hold
> value
> of user-defined matrix vector product.
>
> I have passed a user-defined function to tell MatShell how to create
> left/right Vec(s);
> where I also set left/right->ops->getarray = PETSC_NULL. If vt1 was created
> using
> this routine, there would not have been any error related to
> VecGetArrayRead routine
> and should have printed some tracer printf statements. So my guess is that
> this temporary
> vector is created by directly calling VecDuplicate routine which sets
>  vec->ops->getarray = VecGetArray_Nest by default.
>
>
> On Fri, Mar 1, 2013 at 1:07 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>>>
>>> Where should this routine be added and how should it look like for shell
>>> vectors? I had assumed that
>>> such changes should be done in user defined MatGetVecs routine. Clearly
>>> this is not happening.
>>
>>
>> Please explain.
>
>
>
>
>
> --
> Amneet
>
>
>
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