PCNN-preconditioner and "floating domains"

Barry Smith bsmith at mcs.anl.gov
Tue Jun 23 11:23:21 CDT 2009

    To modify the code for elasticity is a big job. There are two  
faculty Axel Klawonn and O. Rheinbach
at Universität Duisburg-Essen who have implemented a variety of these  
fast methods for elasticity.
I suggest you contact them.


On Jun 23, 2009, at 11:15 AM, Andreas Grassl wrote:

> Barry Smith schrieb:
>>   As we have said before the BNN in PETSc is ONLY implemented for a
>> scalar PDE with
>> a null space of the constant functions. If you shove in linear
>> elasticity it isn't really going to work.
> Do you have any suggestions to work around this drawback?
> Do I understand right, that this issue is problematic, if floating  
> subdomains
> appear?
> Do I have the possibility to provide the null space from user site?
> Or how big would be the effort to change the nn-code to work for  
> this problem
> classes?
> Is such a work useful at all or do you regard BNN only a rather  
> complicated
> method to be done much better by other (even simpler) algorithms?
> Cheers,
> Ando
> -- 
> /"\                               Grassl Andreas
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