[petsc-users] segv in VecSum when using nested vec

[Klaij, Christiaan]

> > >Could you get a stack trace with gdb? Also, I ran on petsc-dev.
> >
> > Breakpoint 1, vecsumsegv::vecsumsegv (this=0x7fffffffd310, m=3, n=4)
> >    at vecsumsegv.cc:28
> > 28        ierr = VecSum(x,&val);
> > (gdb) next
>
>
> This was fixed in petsc-dev.
>
> http://petsc.cs.iit.edu/petsc/petsc-dev/rev/3b9bc425b217

Thanks, I'll switch to petsc-dev for this.

>
>
> Why are you using VecNest? It causes more harm than good in all but some
> very special circumstances.

I'm using it to experiment with PETSc's block preconditioners. In
short, I have a block matrix for the 2D Stokes eqs with the
variables arranged as (u1,...,uN,v1,...,vN,p1,...pN). The matrix
has the form A = [Q G, D 0]. I'm using VecCreateNest to assemble
the vector x = [u p], just like I use MatCreateNest to assemble
the matrix A from the blocks Q, G and D. The index sets are the
ones you helped me with in a previous thread
(https://lists.mcs.anl.gov/mailman/htdig/petsc-users/2012-February/012262.html)


dr. ir. Christiaan Klaij
CFD Researcher
Research & Development
E mailto:C.Klaij at marin.nl
T +31 317 49 33 44

MARIN
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