[petsc-users] Node renumbering and ghost nodes determination

[Jed Brown]

There is no single correct way to do this so you can do whatever makes
the most sense for your application.  That ranges from calling ParMETIS
directly and creating a numbering using any scheme you like to using
PETSc functions for everything.  Note that assembled linear algebra
(matrices and vectors) cares about the dof connectivity graph which is
different from the element graph.  Some people (usually those using
lowest order methods) don't pay attention to elements at all (even
integrating elements redundantly instead of communicating again) while
others focus entirely on elements and make arbitrary decisions about
vertex ownership.  For every choice, you can find someone that did it
one way and someone else that did it the other way -- both will be
convinced that their choice was the only correct choice.

Guido Giuntoli <giuntoli1991 at gmail.com> writes:

> Hi,
>
> I am using ParMETIS to get a partition of my mesh (a group of elements for
> each process) and now I want to renumber the nodes contiguous for each
> process according to their rank. Can I take advantage of the IS functions
> (or others like AO) directly from this point or is crucial to do the
> partition with ParMETIS using PETSc functions and apply
> ISPartitionToNumbering like in the manual's example ?
>
> Another question, which is the best way of determine the ownership of the
> nodes ? for example : node 101 belongs to an element in process 0 and to an
> element in process 1, how do I  take the decision ? In the past I did a
> partition with METIS and he returned an array of nodes belonging like the
> elements so that was easy but now my only idea is to get the new
> renumbering and check if the new renumbering fall inside my range.
>
> Thank you, Guido.
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