# Cooley-Tukey FFT: You don't have to zeropad to a power of 2? [closed]

Someone wrote "The algorithm that Cooley and Tukey presented in their classic paper (Math. Comp. 19 (1965), 297-301. http://dx.doi.org/10.1090/S0025-5718-1965-0178586-1) can be applied to any composite length. The performance advantages are greatest for highly composite lengths, of which powers-of-2 are one example, and lengths of powers-of-2 result in other advantages on binary computers, so it has become a common misconception that the algorithm is only applicable to signals whose length is a power of 2."

Does that mean that when you DO use the Cooley-Tukey FFT You don't have to zeropad to a power of 2? Take for example an image of 1920x1080. So, if you want to use the Cooley-Tukey FFT, you don't need to zeropad that to 2048*2048?

## closed as too localized by Dilip Sarwate, Peter K.♦Jun 8 '13 at 15:21

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• You're confusing the algorithm with its available implementations. Anyway, you've now asked around 10 very similar questions all on the same subject and received lots of good answers - it's probably time to actually try some of the many suggestions you've received and see what works for you. – Paul R Jun 2 '13 at 21:22
• Different versions of this question have been posted by the OP on math.SE and cs.SE (and possibly other SE sites) in addition to dsp.SE. – Dilip Sarwate Jun 3 '13 at 10:52
• The math.SE version appears to have been deleted. I can't see a cs.SE version. @user8005: Please be polite. Your comment was deleted by me for being borderline offensive. – Peter K. Jun 4 '13 at 0:28
• @PeterK. Thanks. The math.SE version is still open while the cs.SE version has been closed. – Dilip Sarwate Jun 4 '13 at 2:42
• @DilipSarwate: Thanks for the links! Google threw up this link as a search result, so I assumed the math.SE one was closed. – Peter K. Jun 4 '13 at 2:51