Figure Properties - SERC

fftn
2fftn
Purpose Multidimensional discrete Fourier transform
Syntax Y = fftn(X)
Y = fftn(X,siz)
Description Y = fftn(X) returns the discrete Fourier transform (DFT) of X, computed
with a multidimensional fast Fourier transform (FFT) algorithm. The result Y
is the same size as X.
2-754
Y = fftn(X,siz) pads X with zeros, or truncates X, to create a
multidimensional array of size siz before performing the transform. The size
of the result Y is siz.
Algorithm fftn(X) is equivalent to
Data Type
Support
Y = X;
for p = 1:length(size(X))
Y = fft(Y,[],p);
end
This computes in-place the one-dimensional fast Fourier transform along each
dimension of X. The execution time for fft depends on the length of the
transform. It is fastest for powers of two. It is almost as fast for lengths that
have only small prime factors. It is typically several times slower for lengths
that are prime or which have large prime factors.
Note You might be able to increase the speed of fftn using the utility
function fftw, which controls how MATLAB optimizes the algorithm used to
compute an FFT of a particular size and dimension.
fftn supports inputs of data types double and single. If you call fftn with
the syntax y = fftn(X, ...), the output y has the same data type as the input
X.
See Also fft, fft2, fftn, fftw, ifftn