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ifft | Examples See Also |
Inverse one-dimensional fast Fourier transform
y = ifft(X) y = ifft(X,n) y = ifft(X,[],dim
) y = ifft(X,n,dim
)
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
.
For any x
, ifft(fft(x))
equals 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 n
=
length(x)
. So the execution time is fastest when n
is a power of 2 and slowest when n
is a large prime.
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