[petsc-users] Edge-cut information for CHACO

[Stefano Zampini]

In DMPLEX, we compute the unweighted edge cut with this code https://gitlab.com/petsc/petsc/blob/master/src/dm/impls/plex/plex.c#L955 <https://gitlab.com/petsc/petsc/blob/master/src/dm/impls/plex/plex.c#L955>
You may reuse most of this code to compute the edge cut in your case

> On Dec 5, 2019, at 10:34 PM, Mark Adams <mfadams at lbl.gov> wrote:
> 
> 
> 
> On Thu, Dec 5, 2019 at 11:20 AM Eda Oktay <eda.oktay at metu.edu.tr <mailto:eda.oktay at metu.edu.tr>> wrote:
> Hello all,
> 
> I am trying to find edge cut information of ParMETIS and CHACO. When I use ParMETIS, 
> MatPartitioningViewImbalance(part,partitioning)
> works and it gives also number of cuts.
> 
> However, when I used CHACO, it only gives imbalance information, not edge cut. I have index sets but I couldn't find how to calculate edge cut.
> 
> I've never heard of edge-cuts wrt Chaco. I'm sure it does not collect that information but you could look at the code.
>  
> 
> Also, does ParMETIS calculate edge cuts according to the values of weights or number of weights?
> 
> Good question, I would assume this is an integer, the number of edge cuts, and not the sum of the weights. If it prints and integer then that would be a hint. 
>  
> 
> Thanks!
> 
> Eda

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