[petsc-users] DMSWARM particle coordinates per rank

[Matthew Young]

Okay, cool.
Should I do that by explicitly setting each particle's DMSwarmField_rank
when I assign its position?
What role does DMSwarmMigrate play in all of this?

--Matt
==========================
Matthew Young, PhD (he/him)
Research Scientist II
Space Science Center
University of New Hampshire
Matthew.Young at unh.edu
==========================


On Fri, May 12, 2023 at 10:05 AM Matthew Knepley <knepley at gmail.com> wrote:

> On Fri, May 12, 2023 at 9:40 AM Matthew Young <
> myoung.space.science at gmail.com> wrote:
>
>> Got it.
>>
>> I'm specifically thinking about this in terms of the gather stage of my
>> PIC code, where I loop over local particles to fill local density and flux
>> arrays by linearly interpolating particle positions to the grid. The gather
>> function currently assumes that the coordinates (i.e., the array
>> representation of DMSwarmPICField_coor) of all particles on a given rank
>> would correspond to only the global indices owned by that rank, via the
>> relationship between indices and coordinates in the associated cell DM.
>> Based on what you described, it sounds like I need to make sure that I
>> initially lay down the particles so that their rank matches their
>> coordinates.
>>
>
> Right now, yes. I will fix that before August.
>
>   Thanks,
>
>     Matt
>
>
>> --Matt
>> ==========================
>> Matthew Young, PhD (he/him)
>> Research Scientist II
>> Space Science Center
>> University of New Hampshire
>> Matthew.Young at unh.edu
>> ==========================
>>
>>
>> On Fri, May 12, 2023 at 5:15 AM Matthew Knepley <knepley at gmail.com>
>> wrote:
>>
>>> On Thu, May 11, 2023 at 9:15 PM Matthew Young <
>>> myoung.space.science at gmail.com> wrote:
>>>
>>>> Does setting up a PIC-type DMSWARM with an associated cell DM guarantee
>>>> that each MPI rank will own the particles with coordinates inside the
>>>> bounds of the portion of the grid it owns?
>>>>
>>>
>>> There is a caveat that we are currently fixing. Swarm communication is
>>> setup to be nearest neighbor (since there is no coarse grid of
>>> bounding boxes). So if your particles are initially in the right place, and
>>> only move nearest neighbor, everything is fine. We are adding a hierarchy
>>> of bounding boxes so that we can communicate anywhere.
>>>
>>>   Thanks,
>>>
>>>       Matt
>>>
>>>
>>>> --Matt
>>>> ==========================
>>>> Matthew Young, PhD (he/him)
>>>> Research Scientist II
>>>> Space Science Center
>>>> University of New Hampshire
>>>> Matthew.Young at unh.edu
>>>> ==========================
>>>>
>>>
>>>
>>> --
>>> What most experimenters take for granted before they begin their
>>> experiments is infinitely more interesting than any results to which their
>>> experiments lead.
>>> -- Norbert Wiener
>>>
>>> https://www.cse.buffalo.edu/~knepley/
>>> <http://www.cse.buffalo.edu/~knepley/>
>>>
>>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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