Comparison of Gwyddion 2.7 simpleFFT transform speed with FFTW3.1 in using
ESTIMATE plans (FFTs are typically one-shot in Gwyddion) and
FFT hum (the old Gwyddion FFT procedure).
The test was performed on Athlon64 with
with split real and imaginary arrays (as is normal in Gwyddion) of stride 1.
Repeated FFTW3 means a plan was created and then executed many times (how
many exactly depended on the transform size, larger ones were executed fewer
times to keep the testing time finite), one-shot FFTW3 means a plan was
created, executed and destroyed for each transform. FFT hum has no planning
and simpleFFT has a very simple fixed planning method, executed each
Normalized execution time is the execution time divided by n log(n), where n is the transform size. This nicely visualizes overheads and failures to scale.