[petsc-users] is something wrong with nnz ?

[jean-frederic thebault]

Hi,

I'm wondering what's wrong in my code. I'm using PETSc to solve a linear
system, and willing to use a multi-processor computer. 9 years ago, I used
petsc-2.1.3 with success. Few weeks ago, I've update petsc with the 3.1-p8
version and made the necessary changes to work with. No problem. And
recently, I've migrate to petsc-3.2-p5. Compilation is OK. But when I do
simulation, now, I have some PETSC-ERROR in the log file, even using only
one processor (see the out.log file in this email). However, I think I
defined MatMPI and VecMPI correctly, according to the doc. The log file
tell that something wrong with the nnz which should not be greater than row
length (??). I can't see what's wrong.

And also, with the previous version of PETSc I've used, the were no problem
using -pc_type bjacobi and -sub_pc_type sor, juste to solve linear system
doing parallel computations and because SOR is not parallelized. But now,
when I use -pc_type bjacobi and -sub_pc_type sor, with 3 rank, I experiment
some convergence problem during my simulation.

I'd really like to calculate in parallel because of, in further time, with
the 2.1.3 petsc version, with a cluster and a myrinet switch, I obtained
some interesting results in terme of performance (that time, the more
number of processors I used, the faster the calculations were). But now,
with the new architecture-PC (2 quad core processors, and no switch of
course, all is in the same computer), each time I do the simulation with
one more processor, I lost time). Any idea of what's wrong ?
I would appreciate some help in that purpose

Best Regards.
John
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