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 |

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