MATLAB Function Reference |
Shift zero-frequency component of discrete Fourier transform to center of spectrum
Syntax
Description
Y = fftshift(X)
rearranges the outputs of fft
, fft2
, and fftn
by moving the zero-frequency component to the center of the array. It is useful for visualizing a Fourier transform with the zero-frequency component in the middle of the spectrum.
For vectors, fftshift(X)
swaps the left and right halves of X
. For matrices, fftshift(X)
swaps the first quadrant with the third and the second quadrant with the fourth.
For higher-dimensional arrays, fftshift(X)
swaps "half-spaces" of X
along each dimension.
Y = fftshift(X,dim)
applies the fftshift
operation along the dimension dim
.
Examples
has Y(1,1)
=
sum(sum(X))
; the zero-frequency component of the signal is in the upper-left corner of the two-dimensional FFT. For
this zero-frequency component is near the center of the matrix.
See Also
circshift
, fft
, fft2
, fftn
, ifftshift
fftn | fftw |
© 1994-2005 The MathWorks, Inc.