ifft

Purpose

Inverse 1-D fast Fourier transform.

Synopsis

y = ifft(x) 
y = ifft(x,n)

Description

ifft(x) is the inverse fast Fourier transform of vector x.

ifft(x,n) is the n-point inverse FFT.

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

fft, fft2, fftshift, filter
dftmtx, freqz, specplot, and spectrum in the Signal Processing Toolbox

(c) Copyright 1994 by The MathWorks, Inc.