On Thu, Oct 17, 2013 at 1:00 PM, James Snyder <[email protected]> wrote:
> I guess I have part of my answer from an older question I asked last year:
> http://permalink.gmane.org/gmane.comp.python.fipy/2353
>
> In there Jonathan mentioned:
>>
>> The issue is that flux is a FaceVariable and although we define a
>> globalValue for FaceVariables, it
>> doesn't look like it has a clear meaning. The issue is that there are
>> cells and faces that overlap multiple
>> processors. The globalValue for a CellVariable properly accounts for the
>> ghost cells, but
>> FaceVariables do not. There hasn't been any internal need to and we
>> suspect that clearing it up will be a
>> mess (there is an ambiguity with faces that doesn't exist with cells; some
>> faces are shared between
>> processors even for non-overlapping cells). We do need to examine whether
>> globalValue should even be
>> defined for anything besides CellVariables.

Thanks for bringing this up again, we should move "globalValue" and
"_getGlobalVaue" method to "CellVariable" and out of "_MeshVariable".
As explained, a global face variable is hard to calculate in the
general case.

> Since what I'm trying to do is just get face centers so I can make a convex
> hull around what is essentially an internal "hole" in the mesh. If I just
> want to merge the face centers from each process should I use MPI comm
> primitives to pull them together or is there a cleaner way to get this
> within the existing framework?

I'm not really sure what you are trying to do here. What is the
purpose? Maybe there is another way.

> Also, congrats on getting 3.1 out, especially in terms of timing :-)

Thanks very much.

How are you findining using FiPy in parallel? What sort of speed ups
are you getting?

-- 
Daniel Wheeler
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