[Numpy-discussion] strange runtimes of numpy fft

[Robert Kern]

On Thu, Nov 14, 2013 at 4:45 PM, Charles Waldman <charles at crunch.io> wrote:
>
> Can you post the raw data?  It seems like there are just a couple of
"bad" sizes, I'd like to know more precisely what these are.
>
> It's typical for FFT to perform better at a sample size that is a power
of 2, and algorithms like FFTW take advantage of factoring the size, and
"sizes that are products of small factors are transformed most efficiently."

These are the sizes, as given in the notebook he supplied:

array([     100,      161,      261,      421,      681,     1100,
           1778,     2872,     4641,     7498,    12115,    19573,
          31622,    51089,    82540,   133352,   215443,   348070,
         562341,   908517,  1467799,  2371373,  3831186,  6189658,
10000000])

--
Robert Kern
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