[Dune] difference between OwnerOverlapCopyAttributeSet::copy and OwnerOverlapCopyAttributeSet::overlap

[Andreas Lauser]

Hi Dune,

Today I was wrestling with my and dune-istl's parallelization code once again. 
During that, I started to wonder what the difference between 
OwnerOverlapCopyAttributeSet::copy and OwnerOverlapCopyAttributeSet::overlap 
is. I could not find anything in the doxygen documentation, and the 
corrosponding lines in dune/istl/owneroverlapcopy.hh read:

struct OwnerOverlapCopyAttributeSet
  {
        enum AttributeSet { 
          owner=1, overlap=2, copy=3 };
  };

what made me wonder even more, is that the code in 
dune/istl/paamg/test/anisotropic.hh (which creates the matrix for the parallel 
AMG test) does not use OwnerOverlapCopyAttributeSet::overlap even though the 
matrix which it creates clearly corresponds to one which stems from an 
overlapping grid. (if I understood that code correctly.)

can anyone with deeper insight on ISTL tell the difference?

cheers
  Andreas

-- 
Andreas Lauser
Department of Hydromechanics and Modelling of Hydrosystems
University of Stuttgart
Pfaffenwaldring 61
D-70569 Stuttgart
Phone: (+49) 711 685-64719
Fax: (+49) 711 685-60430
www.hydrosys.uni-stuttgart.de