|MATLAB Function Reference|
Inverse discrete Fourier transform
y = ifft(X)
returns the inverse discrete Fourier transform (DFT) of vector
X, computed with a fast Fourier transform (FFT) algorithm.
X is a matrix,
ifft returns the inverse DFT of each column of the matrix.
X is a multidimensional array,
ifft operates on the first non-singleton dimension.
y = ifft(X,n)
n-point inverse DFT of vector
y = ifft(X,,dim)
y = ifft(X,n,dim) return the inverse DFT of
X across the dimension
X to within roundoff error. If
X is real,
ifft(fft(X)) may have small imaginary parts.
The algorithm for
ifft(X) is the same as the algorithm for
fft(X), except for a sign change and a scale factor of
length(X). As for
fft, the execution time for i
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.
freqz, in the Signal Processing Toolbox