On Thu, Nov 19, 2015 at 11:05 PM, Frank Loeffler <[email protected]> wrote:
> On Fri, Nov 20, 2015 at 04:41:48AM +0000, Garrison, David wrote: > > How do you find the number of non-zero elements in a Grid Function in > Cactus? > > The best way would probably be to count them locally on each process, > write the result in a distributed grid array, and do the sum there by > syncing the array and counting locally (not sure if a reduction on such > an array would work, it might). > There is no need for a distributed grid array. After counting locally, a "local reduction" (i.e. reduction of a local variable) gives you the overall result. -erik Another, but more expensive way (in terms of memory size and memory > accesses) would be to create another grid function, populate it with > either 1 or 0 depending on the non-zero-property of the GF you are > interested in, and calling the existing sum-reduction on it. > > Frank > > > _______________________________________________ > Users mailing list > [email protected] > http://lists.einsteintoolkit.org/mailman/listinfo/users > > -- Erik Schnetter <[email protected]> http://www.perimeterinstitute.ca/personal/eschnetter/
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