[petsc-users] ParMETIS vs. CHACO when no partitioning is made

[Barry Smith]

   Could be a bug in Chaco or its call from PETSc for the special case of one process. Could you send a sample code that demonstrates the problem?

  Barry


> On Aug 14, 2020, at 8:53 AM, Eda Oktay <eda.oktay at metu.edu.tr> wrote:
> 
> Hi all,
> 
> I am trying to try something. I am using the same MatPartitioning codes for both CHACO and ParMETIS:
> 
> ierr = MatConvert(SymmA,MATMPIADJ,MAT_INITIAL_MATRIX,&AL);CHKERRQ(ierr);  
>   ierr = MatPartitioningCreate(MPI_COMM_WORLD,&part);CHKERRQ(ierr);
>   ierr = MatPartitioningSetAdjacency(part,AL);CHKERRQ(ierr); 
>   
>   ierr = MatPartitioningSetFromOptions(part);CHKERRQ(ierr);
>   ierr = MatPartitioningApply(part,&partitioning);CHKERRQ(ierr);
> 
> After obtaining the IS, I apply this to my original nonsymmetric matrix and try to get an approximate edge cut. 
> 
> Except for 1 partitioning, my program completely works for 2,4 and 16 partitionings. However, for 1, ParMETIS gives results where CHACO I guess doesn't since I am getting errors about the index set.
> 
> What is the difference between CHACO and ParMETIS that one works for 1 partitioning and one doesn't?
> 
> Thanks!
> 
> Eda