[petsc-users] Database key for KSP_Solve

[Matthew Knepley]

On Fri, Jun 15, 2012 at 4:22 AM, Xuefeng Li <li at loyno.edu> wrote:

> On Fri, 15 Jun 2012, Matthew Knepley wrote:
>
>  On Fri, Jun 15, 2012 at 3:08 AM, Xuefeng Li <li at loyno.edu> wrote:
>>
>>  Are there any database keys to control the number of
>>> times KSP_Solve() is called? Where is the loop that
>>> calls KSP_Solve?  The key -ksp_max_it does not seem
>>> to affect it.
>>>
>>>
>> Then this option did not reach the solver. You may have set a prefix.
>>
>> Run with -snes_max_it 1 -ksp_max_it 1 -snes_view to see what you are
>> actually doing.
>>
>>  The key -ksp_max_it affects the iteration number
> for the (main) ksp object for SNES, but not the ksp
> object for PC.
>

1) Why do you have a KSP object underneath your PC?

2) Since you do -sub_ksp_max_it 1 would be the default


> I observed yet another (related) problem. Even though
> I set KSP type to be GMRES, the type is GMRES only on
> the coarse level of the DMMG; the type changes to MG
> on all finer levels. How do I control KSP and PC on
> finer levels of DMMG?
>

3) Don't use DMMG, it has been replaced with something much simpler in the
latest release
    There you can give -mg_levels_ksp_type

   Matt


>
> Regards,
>
> --Xuefeng Li, (504)865-3340(phone)
>  Like floating clouds, the heart rests easy
>  Like flowing water, the spirit stays free
>       http://www.loyno.edu/~li/home
>  New Orleans, Louisiana (504)865-2051(fax)
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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