Discrete Fourier transform

The `dsp.FFT`

System
object™ computes the discrete Fourier transform (DFT) of an input using fast Fourier
transform (FFT). The object uses one or more of the following fast Fourier transform (FFT)
algorithms depending on the complexity of the input and whether the output is in linear or
bit-reversed order:

To compute the DFT of an input:

Create the

`dsp.FFT`

object and set its properties.Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects? (MATLAB).

`ft = dsp.FFT`

`ft = dsp.FFT(Name,Value)`

returns a `ft`

= dsp.FFT`FFT`

object, `ft`

, that computes the DFT of
an *N*-D array. For column vectors or multidimensional arrays, the
`FFT`

object computes the DFT along the first dimension.
If the input is a row vector, the `FFT`

object computes a
row of single-sample DFTs and issues a warning.

returns a `ft`

= dsp.FFT(`Name,Value`

)`FFT`

object with each specified property set to
the specified value. Enclose each property name in single quotes. Unspecified properties
have default values.

**For versions earlier than R2016b, use the step
function to run the System object algorithm. The arguments to
step are the object you created, followed by
the arguments shown in this section.**

**For example, y = step(obj,x) and y = obj(x) perform equivalent operations.**

`y = ft(x)`

To use an object function, specify the
System
object as the first input argument. For
example, to release system resources of a System
object named `obj`

, use
this syntax:

release(obj)

This object implements the algorithm, inputs, and outputs described on the FFT block reference page. The object properties correspond to the block parameters.

[1] FFTW (`http://www.fftw.org`

)

[2] Frigo, M. and S. G. Johnson, “FFTW: An Adaptive Software
Architecture for the FFT,” *Proceedings of the International Conference on
Acoustics, Speech, and Signal Processing*, Vol. 3, 1998, pp. 1381-1384.