# Does Mathematica implement the fast Fourier transform?

Is there a fast Fourier transform in Mathematica? Although looking in the help I could not find one.

I am looking to implement the equivalent of fft in MATLAB.

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Fourier[list] computes the discrete Fourier transform of list. I assume it uses the FFT when it can.

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Note that the normalization used by Mathematica is quite different from conventional (e.g. physics, signal processing) normalizations. Check the definition you are using, and set the option FourierParameters accordingly. –  Ｊ. Ｍ. Feb 2 '12 at 14:15
Is there a way to strip it out ? In Matalab syntax I need to do the following : function fs = MyFFT(fx) y = fftshift(fx); tmp = fft(y)/sqrt(length(fx)); fs = fftshift(tmp); –  500 Feb 2 '12 at 14:27
fftshift[vec_?VectorQ] := RotateRight[vec, Quotient[Length[vec], 2]] –  Ｊ. Ｍ. Feb 2 '12 at 14:39
For reference: MATLAB's fft(stuff) is equivalent to Mathematica's Fourier[stuff, FourierParameters -> {1, -1}]. To do fft(y)/sqrt(length(y)), one doesn't need to do an explicit division, as the adjustment of FourierParameters is all that's needed: Fourier[y, FourierParameters -> {0, -1}]. –  Ｊ. Ｍ. Feb 2 '12 at 15:00
@J.M. Thank You very much for the explanation, well it is actually the answer to my question... –  500 Feb 3 '12 at 3:50
Fourier uses FFT when possible