Performance info for different 2D FFT versions

[davva]

I am performing 2D FFT on real data with dimensions 512x512. It is however for simplicitly implemented as a 1024x1024 complex FFT.

I have been searching the Inte pages for info on speed comparing all different 2D FFTs, real, complex, in-place, out of place.

Where can I find som doc on this? Or maybe someone can tell me this info in this thread?

Thanx

[Dmitry_B_Intel]

Hi davva

You can find some performance data on MKL web page, look into FFT section.

Thanks
Dima

[davva]

Hi!

On the MKL web page I could only find one single comparison (2D FFT vs FFTW for two platforms). I want to compare different 2D FFTs on the same platform.

E.g. how much faster is real 2D fft than a complex?

E..g how much faster/slower is in-place than out of place?

[Dmitry_B_Intel · Accepted solution]

Real to complex transform can be ~2 times faaster than complex-to-complex transform on the same number of elements, 2D or 1D.

The in-place transform is typically slightly faster than out-of-place transform, for it uses less memory transfers. However, it may also be slower, if in-place requires these transfers for particular settings of the problem. This may happen for example if non-unit strides are used.

Dima