First run with -pc_type lu what happens? Then run small problems with
-mat_view and see if the matrix entries look reasonable, also check that the
right hand side vector entries look reasonable.
Barry
On Oct 13, 2011, at 3:04 AM, Marco Cisternino wrote:
Hi to everybody,
I wrote an interface elliptic problem solver in 2D and 3D. The linear system
I assemble depends on the geometrical characteristics of a level set
function. I tested them with several and more and more complex interfaces,
but now I would try it with a real 3D interface. But I probably have some
problem with the computation of a good level set function, maybe the cause is
the low resolution of the original interface. The evidence of my problem is
in the subject. No matter what iterative petsc solver I try to use the run
stops at the first iteration with a Nan residual. I don't want to ask you to
understand the problem, but to give me some information about how to debug I
situation like this. The interface is too complex to be deeply checked, then
I hope that looking how the ksp yields a nan residual could help me.
Thank you so much.
Best regards,
Marco
--
Marco Cisternino
PhD Student
Politecnico di Torino
Mobile:+393281189696
Email:marco.cisternino at polito.it
