Beowulf & FFT

Josip Loncaric josip at
Wed Jul 19 08:48:14 PDT 2000

Martin Siegert wrote:
> The authors of FFTW claim that this is the fastest FFT you can get. 

I second that.  The FFTW library runs great on a wide range of
machines.  However, FFT is a global transform, and it requires
all-to-all communication at some point.  If you can break your problem
into spectral "bricks" then you can reduce the amount of communication
to some boundary condition between these "bricks".  This gives you a win
thanks to a favorable surface/volume ratio, but the internal boundary
conditions are typically of lower order of accuracy.  While you will not
get spectral accuracy, in most applications going beyond order 6-10 does
not help much.  I believe that A. Patera (MIT) had some papers on such


Dr. Josip Loncaric, Senior Staff Scientist        mailto:josip at
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