[dune-pdelab] some problems in dune

[Rebecca de Cuveland]

Hey,

why did you change the coarsentarget parameter? The default is somewhere 
at 1000 nodes, and it seems you have 1? That is certainly not a 
reasonable choice. (You have only one unknown on your coarsest level).

I also see in your code that you do not use Superlu as solver on the 
coarsest level (usesuperlu = false). As the warning that you explicitly 
supress with this flag states: Use superlu, sometimes this has a drastic 
impact on the solution.

Does something change, when you use superlu and a coarsentarget of at 
least 100 (or even more)?

One last thing, we spoke about AMG in combination with Q2 today in our 
group meeting:
Nobody has really used this in pdelab, and we are not sure if the 
implementation in istl is also valid for Q2. Perhaps Markus can say 
something about that?

Bye,
Rebecca

-- 
Rebecca de Cuveland
Universität Heidelberg
Interdisziplinäres Zentrum für Wissenschaftliches Rechnen
Im Neuenheimer Feld 368, 69120 Heidelberg
Tel: 06221/548890   Fax: 06221/548884
e-mail: <rebecca.cuveland at iwr.uni-heidelberg.de>

On 31.10.2014 11:36, Robert Jendrny wrote:
> Hey,
>
> please find "more" output attached
>
> I think I know where the problem is: CG should have monotone 
> convergence, but I do not get it ... Why?
>
> Robert
>
> P.S.: Stopping criteria: 1E-6
>
>
> On 10/31/2014 11:14 AM, Robert Jendrny wrote:
>> Sorry,
>>
>> I found it ;-)
>>
>> On 10/31/2014 11:10 AM, Robert Jendrny wrote:
>>> Hi,
>>>
>>> I do not know how to set the verbosity :-(
>>>
>>> Robert
>>>
>>> On 10/31/2014 11:04 AM, Rebecca de Cuveland wrote:
>>>> Hey Robert,
>>>> could you please send some more verbose output? (verbosity 3 or 4 
>>>> for AMG and 1 for linear solver). normally this is the last 
>>>> parameter of the constructors.
>>>> I would like to see the initial defect, end defect and some more 
>>>> information about the AMG.
>>>> Thanks,
>>>> Rebecca
>>>>
>>>
>>>
>>
>>
>
>