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Inverse one-dimensional fast Fourier transform

Syntax

Description

y = ifft(X) returns the inverse fast Fourier transform of vector X.

If X is a matrix, ifft returns the inverse Fourier transform of each column of the matrix.

If X is a multidimensional array, ifft operates on the first non-singleton dimension.

y = ifft(X,n) returns the n-point inverse fast Fourier transform of vector X.

y = ifft(X,[],dim) and y = ifft(X,n,dim) return the inverse discrete Fourier transform of X across the dimension dim.

Examples

For any x, ifft(fft(x)) equals x to within roundoff error. If x is real, ifft(fft(x)) may have small imaginary parts.

Algorithm

The algorithm for ifft(x) is the same as the algorithm for fft(x), except for a sign change and a scale factor of n = length(x). So the execution time is fastest when n is a power of 2 and slowest when n is a large prime.

See Also

dftmtx, freqz, specplot, and spectrum in the Signal Processing Toolbox, and:

fft         One-dimensional fast Fourier transform

fft2        Two-dimensional fast Fourier transform

fftshift    Shift DC component of fast Fourier transform to center of spectrum



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