I discovered, rather by accident, that the FFTW planner seems to get its
knickers royally in a twist for certain FFT sizes. The code
d_plan = fftwf_plan_dft_1d (fft_size,
reinterpret_cast<fftwf_complex
*>(d_inbuf),
reinterpret_cast<fftwf_complex
*>(d_outbuf),
forward ? FFTW_FORWARD : FFTW_BACKWARD,
FFTW_MEASURE);
Goes away and computes forever for FFT sizes of 3200000 and 6400000. I
know that FFTW tries to compute
and “optimized” algorithm based on size, etc. I guess that there are
singularities in the optimizer??
I was trying to add various sizes other than {1,2,4,8}M bins, with 3.2M
and 6.4M being obvious intermediate
sizes, which seems to have provoked this problem. I’m running with
FFTW-3.2.
–
Marcus L.
Principal Investigator, Shirleys Bay Radio Astronomy Consortium