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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Fourier
Date: Fri, 17 Jul 2009 23:53:06 +0000 (UTC)
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>I look for general N, simple to use, basic to analyse data energy
>coherence.
  I use a Glassman algorithm version.  It's fast for highly composite
N (eg, powers of 2), but slow for prime sizes.  For FFTing images, that
could be very slow indeed, so I use a companion utility to find the
operation count for each K in N ..  N+20 to see if a small extension of
the data will substantially speed things up.