Hi Eric,
Any one want to speculate on the timing difference for the 4095 vice 4096 long transforms ? Since 4095 is not a power of two I would have expected a greater time difference (DFT vice FFT)
You are correct in that 4095 is not a power of two, but is is the product of only small prime factors: 3 * 3 * 5 * 7 * 13 = 4095 Since the FFT code implements a N*log_2(N) algorithm for numbers that contain only small prime factors, the difference in times is rather small. FFTs that have lengths that are powers-of-two tend to be more efficient in general (since the decimation routines are cleaner for this case). If you test with 4097 (17 * 241) it will be quite a bit slower I'd guess... Scott -- Scott M. Ransom Address: Harvard-Smithsonian CfA Phone: (617) 495-4142 60 Garden St. MS 10 email: ransom@cfa.harvard.edu Cambridge, MA 02138 GPG Fingerprint: 06A9 9553 78BE 16DB 407B FFCA 9BFA B6FF FFD3 2989