[petsc-users] Petsc has generated inconsistent data - Divide by zero!

[Jed Brown]

On Sat, Jul 9, 2011 at 17:43, TAY wee-beng <zonexo at gmail.com> wrote:

> Sorry about that. I just run interactively to get the output.
>
> Now I issued :
>
> mpiexec -np 1 ./a.out  -ksp_type gmres -ksp_gmres_restart 1000
> -ksp_gmres_modifiedgramschmidt -ksp_monitor_true_residual -ksp_view -pc_type
> asm -sub_pc_type lu > log1
>

Your matrix is singular which implies a bug in your assembly code, probably
in the way you impose boundary conditions. Switch to a very small problem
size (e.g. 4 cells) and debug it until the matrix is correct and
non-singular.

You should also check the error codes so the code doesn't try to keep going
after a fatal error.
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