PETSC-Hypre: number of level with boomeramg

[Fernando Campos]

Dear Nicolas, 

It is a good question, but I don't know the answer... 
Why don't you try to set the maximum levels to a large numbers in order to 
see how many levels boomerAMG creates? I believe that it refines the grid up 
to the maximum number of levels as you sad. 

I am very interested in both geometric and algebraic multigrids and I also 
have a question: "Is it possible to obtain the coarse matrices of each level 
using boomerAMG?" 

Best Regards. 


Em (15:31:40), petsc-users at mcs.anl.gov escreveu: 


>Dear Fernando, 
> 
>Thanks for your reply. 
> 
>I had notice the value maxlevels given by -ksp_view, but I did not know 
>how to change this value. 
> 
>Still, as the default is 25 levels I think, I have no way to know exactly 
>how many levels are used for a given case. 
>I can reformulate my question in this way: does boomeramg coarsen the 
>"grid" to the coarsest level possible, i.e. 1 cell over the domain, or 
>does it stop before that? (grid is not the right term when it comes to 
>algebraic multilevel methods, but I can't find any other clear way to 
>express it). How can I control the coarsening? 
> 
>Thinking about it, perhaps boomeramd actually refines the grid up to the 
>maximum number of levels...Is it so? 
> 
>Thanks for your help. 
> 
>Nicolas 
> 
>> Nicolas, 
>> 
>> You should try the option -pc_hypre_boomeramg_max_levels in the line 
>> command. In order to see the level's details you can use the PESTc option 
>> -ksp_view. 
>> 
>> Best Regards 
>> 
>> Fernando. 
>> 
>> 
>> Em (11:15:45), petsc-users at mcs.anl.gov escreveu: 
>> 
>> 
>>>Hi Petsc users, 
>>> 
>>>I have a question regarding the use of Hypre and especially Boomeramg. 
>>>How can we control the number of levels in the multigrid algortihm? Can 
>>> we 
>>>chose it, or if not, can we display it in some way? 
>>> 
>>>Best regards, 
>>> 
>>>Nicolas. 
>>> 
>>>-- 
>>>Nicolas BATHFIELD 
>>>Chalmers University of Technology 
>>>Shipping and Marine Technology 
>>>phone: +46 (0)31 772 1476 
>>>fax: +46 (0)31 772 3699 
>>> 
>>>---------- 
>> 
>> 
>> 
> 
>-- 
>Nicolas BATHFIELD 
>Chalmers University of Technology 
>Shipping and Marine Technology 
>phone: +46 (0)31 772 1476 
>fax: +46 (0)31 772 3699 
> 
>----------