Re: [pooma-dev] how to apply mutating functors?

[Richard Guenther]

On Tue, 27 Aug 2002, Garnet Kin-Lic Chan wrote:

> Hi -
>
> I've been using POOMA loosely as a framework for distributed arrays of
> objects, and I have many loops where I'd like to apply a functor to each
> of the objects in turn, changing their state. Because each object is
> large, it would not make sense to use a UserFunction and do the copying.

I would suggest using a Stencil for this to stick your functor into and
then just using
  A = yourStencil(A);

> Another thing I've been looking for is the ability to do reductions (in
> particular some kind of summation operation).

You may want to look at how this is implemented f.i. for the min(), max()
reduction functions. Look at Array/Reductions.h and Evaluator/Reduction.h.

> I've had a browse through the code, and my guess is that I will have to
> look at the evalute functions, but I can't quite make
> out whether I can just pick LoopApplyEvaluator::evaluate and things will
> work in parallel? Also is the function clever enough to work with
> reductions, e.g. accumulating things into a variable in a stateful
> functor, in a parallel application? Does anyone have some simple examples
> of this kind of thing?

I dont have examples of simple reductions but like to know myself to how
f.i. reduce a 32x32 array to a 16x16 array by interpolation in a parallel
array operation.

Richard.

--
Richard Guenther <address@hidden>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/
The GLAME Project: http://www.glame.de/