[petsc-users] order dependency in petsc options?

[Geoffrey Irving]

Aside to Jed: yes, rcm seems to work a lot better than nested dissection.

Geoffrey

On Wed, Jan 30, 2013 at 4:32 PM, Geoffrey Irving <irving at naml.us> wrote:
> I'm setting options via
>
>     CHECK(PetscOptionsClear());
>     CHECK(PetscOptionsInsert(&argc,&argv,0));
>
> a while after calling PetscInitialize().  If the options are
>
>     -ksp_rtol 1e-3 -pc_factor_mat_ordering_type nd -ksp_type cg
> -pc_type icc -pc_factor_levels 0 -ksp_max_it 100
>
> it successfully caps CG iterations at 100.  If I use
>
>     -ksp_max_it 100 -ksp_rtol 1e-3 -pc_factor_mat_ordering_type nd
> -ksp_type cg -pc_type icc -pc_factor_levels 0
>
> the maximum iterations are 10000.  I.e., -ksp_max_it work at the end
> but not at the beginning.  What might be causing this order
> dependence?  I'm using
>
>     [0]PETSC ERROR: Petsc Release Version 3.3.0, Patch 3, Wed Aug 29
> 11:26:24 CDT 2012
>
> Thanks,
> Geoffrey