# fftn

N dimensional fast Fourier transform (FFT).

## Syntax

f = fftn(x)

f = fftn(x, dims)

## Inputs

`x`- The signal to be transformed into the frequency domain.
`dims`- The dimension lengths of the FFT.

## Outputs

`f`- The frequency domain representation of
`x`.

## Comments

The dimensions of the FFT, `dims`, default to the dimensions of the matrix
being transformed. If `dims` are not the defaults, the signal matrix is
either truncated or extended with zeros to the specified lengths.

fftn uses the FFTW library.