[petsc-users] Node renumbering and ghost nodes determination

[Guido Giuntoli]

Thank you very much Jed, now I have a clearer explanation and another point
of view of the situation. This is like take the red or blue pill for me...

2017-06-28 21:06 GMT+02:00 Jed Brown <jed at jedbrown.org>:

> 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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