# fftshift

## Purpose

Rearrange the outputs of `fft` and `fft2`.

## Synopsis

    Y = fftshift(X)

## 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`

    Y = fft2(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

    Z = fftshift(Y)

this DC component is near the center of the matrix.

## See Also

    fft, fft2

(c) Copyright 1994 by The MathWorks, Inc.