[petsc-users] non-convergence for SNES ex5 and ex20

[Qian Zhu]

Hi,
        I am running ex5 and ex20 under $PETSC_DIR/src/snes/examples/tutorials. I need to see some non-converged cases. For ex5, I tried different values for "par" while for ex20, "beta" was varied (to create different inputs thus different problems to solve). Now it seems that no matter which solver+pc I used, all cases converged for both applications. Let me explain what I need using an example...For ex5, par=xxx,  using "-ksp_type gmres -pc_type ilu" will make the solution converge while using "-ksp_type cg -pc_type jacobi" cannot (all ksp's and pc's are just randomly picked...they may not make sense). What would this "xxx" value be? Or is there any input parameters I am missing out for these applications?

Thanks a lot!
Qian


Qian Zhu, Ph.D.
Mathematics and Computer Science Division
Argonne National Laboratory
9700 S.Cass Avenue
Argonne, IL 60439-4844
Phone: 630-252-0086