Zero-Padding to the Next Higher Power of 2
Another reason we zero-pad is to be able to use a Cooley-Tukey FFT with any
window length 
. When
is not a power of 
, we append enough
zeros to make the FFT size 
be a power of
. In Matlab and
Octave, the function nextpow2 returns the next higher power
of 2 greater than or equal to its argument:
N = 2^nextpow2(M); % smallest M-compatible FFT size
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Zero-Padding for Interpolating Spectral Displays
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Practical Zero Padding
