[petsc-users] Recommended solver and preconditioner to solve Poisson eqn on win7

[Matthew Knepley]

On Fri, Sep 14, 2012 at 5:40 PM, Zhenglun (Alan) Wei <zhenglun.wei at gmail.com
> wrote:

>  Dear folks,
>     I did some test with -pc_type gamg with
> /src/ksp/ksp/example/tutorial/ex45.c. It is not as good as default -pc_type
> when my mesh (Cartisian) is 100*50*50; while it is a little bit better than
> the default one when the mesh is 200*100*100. Therefore, I guess this type
> of pc is good for larger problem. Is that ture? or is there any rule of
> thumb for this type of preconditioner? BTW, I tested it with 8 processes.
>

When asking questions about convergence, always always ALWAYS send the
output of -ksp_monitor -ksp_view. If
you don't, we are just guessing blindly.

   Matt


> thanks,
> Alan
> On 9/14/2012 9:38 AM, Mark F. Adams wrote:
>
>
>  On Sep 14, 2012, at 8:47 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>
>  On Fri, Sep 14, 2012 at 3:47 AM, TAY wee-beng <zonexo at gmail.com> wrote:
>
>> Hi,
>>
>> I need to solve the Poisson eqn on my win7 machine. I'm currently using
>> BCGS without preconditioner. I can't use HYPRE since I'm using Fortran and
>> win7. It's rather slow.
>>
>> Is there a recommended solver and preconditioner to solve the Poisson eqn
>> to get me started?
>>
>
>  What discretization?
>
>  Run with -pc_type gamg to start.
>
>
>  and
>
>  -pc_gamg_agg_nsmooths 1
>
>  (I should make this the default)
>
>  Mark
>
>
>


-- 
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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