[phobos] FFT

[Don Clugston]

On 2 August 2010 19:49, David Simcha <dsimcha at gmail.com> wrote:
> Oh, also, I don't think that cache effects are the main bottleneck because
> switching to single-precision floats for both input and output has a
> negligible effect on performance even though it cuts the size of the working
> set in half.

Interesting. Still, I think that because of the way FFT works, once
you're bigger than the cache, nearly every memory access will be a
cache miss. It could be that although the memory footprint halves, the
number of cache misses remains constant.

Anyway, the reason I posted the link was not so much to help with
implementation, but more because it gives a great feel for what's
involved in a "state of the art" FFT library. I suspect there's a
sweet spot with high convenience, small code size, and good-enough
performance.