MATLAB Functions Help Desk

fftshift

Purpose

Move zero'th lag to center of spectrum.

Syntax

Description

Y = fftshift(X) rearranges the outputs of fft and fft2 by moving the zero frequency component to the center of the spectrum, which is sometimes a more convenient form.

If X is a vector, Y is a vector with the left and right halves swapped.

If X is a matrix, Y is a matrix with quadrants one and three swapped with quadrants two and four.

Examples

For any matrix X

has Y(1,1) = sum(sum(X)); the DC component of the signal is in the upper-left corner of the two-dimensional FFT. For

this DC component is near the center of the matrix.

See Also

fft         One-dimensional fast Fourier transform

fft2        Two-dimensional fast Fourier transform



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