[petsc-users] problem with initial value

[Jed Brown]

On Fri, Oct 21, 2011 at 11:57, Dominik Szczerba <dominik at itis.ethz.ch>wrote:

> 1) Syscall param writev(vector[...]) points to uninitialised byte(s)
> -> tribbered by MatPartitioningApply, then leading deep into ParMetis
>

If we're lucky, this has been fixed in the latest ParMetis release. (PETSc
can use it, but not all the external packages can yet. We're patching these
before using the new release by default.)


>
> 2) Conditional jump or move depends on uninitialised value(s)     ->
> many times, in VecMin and VecMax and KSPSolve_BCGSL
> and
>
> 3) Syscall param writev(vector[...]) points to uninitialised byte(s)
> -> just once, in VecScatterBegin triggered by VecCreateGhost on the
> 'x' vector, which is ghosted.
>
> Do they pose any serious threats?
>
> >
> >    Have you tried KSPBCGSL? This is "enhanced Bi-CG-stab" algorithm that
> is designed to handle certain situations that may cause grief for regular
> Bi-CG-stab I guess.
> >
>
> Thanks for the hint on bcgsl - it works as expected.
>
> So, do I have a problem in the code or bcgs is unreliable? If the
> latter: as a method or as this specific implementation?
>

It would be much easier to answer these questions if you sent a test case or
showed us how to reproduce the problem with a PETSc example.
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