[Yt-dev] tree code for boundedness

Matthew Turk matthewturk at gmail.com
Thu Mar 3 17:35:16 PST 2011


Hi Stephen,

Yeah, doing the full pairwise summation is pretty slow; the only
instance of CUDA code in yt is actually a CUDA-fied version of this
summation that I wrote for the Turk, Abel, O'Shea 2009 paper, because
our clumps were composed of so many cells we had to speed up the
binding energy calculation.  If you were to write a tree solver, that
would be great, but it might require a bit of effort on your part to
get the cell parentage correct.  One option would be to use the
completely untested, completely unused Octree that I wrote, add all
the cells to it, and then try to get the correct potential out of it.
The problem there is that coarse cells that don't fully cover will
need to have the non-included cells subtracted off.  But maybe you can
figure out a way around this?

-Matt

On Thu, Mar 3, 2011 at 8:15 PM, Stephen Skory <stephenskory at yahoo.com> wrote:
> Hi all,
>
> I've been working with the clump finder, and am becoming impatient with the gravitationally bound test calculation. I'm a very important person! Ok, sorry, I'm back to serious now. I'm wondering if we think that implementing some kind of tree code or pixelation of cells to lower resolution levels would be practical and accurate enough? It would make the double loop much smaller and quicker, and there could be a single user-controlled parameter that sets the desired accuracy. There are even parallel tree codes out there that we may be able to crib from.
>
> Any thoughts would be appreciated!
>
>
> Stephen Skory
> stephenskory at yahoo.com
> http://stephenskory.com/
> 510.621.3687 (google voice)
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