Aaah! Thanks Barry. Just to make sure though, is my assumption on the natural ordering of PETSc correct?
Thanks On Mon, Apr 9, 2012 at 3:10 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > On Apr 9, 2012, at 5:06 PM, Mohammad Mirzadeh wrote: > > > Hi, > > > > I am using 'ISPartitioningToNumbering' to generate new global numbering > from a partitioning indexset and I'm baffled at the following situation. > I'm debugging my code on a simple grid consisting of 81 grid points > partitioned among two processes. When I look into the partitioning indexset > (i.e. looking at the indecies via ISView) I can see that 40 points have > been assigned to proc 0 and 41 to processor 1. Isn't it true that when 81 > points are distributed among two processors 41 should go to proc 0 and 40 > to proc 1? > > > > I have based my whole code on the assumption (verified before through > mailing list i guess) that natural ordering in PETSc leads to a > distribution of points such that all processors get the same number of > points ( [0, n/p) on proc 0, [n/p, 2n/p) on proc 1, ... ) unless n%p != 0, > in which case the first k (with k = n%p) processors receive 1 point extra. > Am I wrong to assume this? > > > > Thanks, > > Mohammad > > > > > PS: Is it relevant that the partitioning indexset is obtained via > ParMetis?partitiong > > Yes, ParMetis provides no guarantee about how many points would get > assigned to each process. > > Barry > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120409/a0fecbf8/attachment.htm>