# getFrequencyVector

Get the vector of frequencies at which the short-time FFT is computed

*Since R2020b*

## Description

## Examples

### Get Short-time FFT Frequencies

Get the frequency vector at which the short-time FFT is computed.

Create a `dsp.STFT`

object. The STFT object is defined with a `'twosided'`

frequency range. The frequency vector is defined by the interval [0 *Fs*] and has the same length as the FFT length, where *Fs* is the input sample rate.

stf = dsp.STFT

stf = STFT with properties: Window: [512x1 double] OverlapLength: 256 FFTLength: 512 FrequencyRange: 'twosided'

When the input sample rate *Fs* is not defined, the frequencies are computed in the interval [0, 2$\pi $].

Using the `getFrequencyVector`

function, get the vector of frequencies at which the STFT is computed.

freq = getFrequencyVector(stf)

`freq = `*512×1*
0
0.0123
0.0245
0.0368
0.0491
0.0614
0.0736
0.0859
0.0982
0.1104
⋮

When the input sample rate *Fs* is defined, the frequency vector is defined by the interval [0 *Fs*].

Fs = 44100; freqFs = getFrequencyVector(stf,Fs)

freqFs =512×110^{4}× 0 0.0086 0.0172 0.0258 0.0345 0.0431 0.0517 0.0603 0.0689 0.0775 ⋮

## Input Arguments

`stf`

— STFT object

`dsp.STFT`

Short-time FFT object whose frequency vector is computed, specified as `dsp.STFT`

object.

`Fs`

— Input sample rate

positive scalar

Input sample rate, specified as a real positive scalar. The STFT frequencies are
computed in the interval determined by `Fs`

. For more details, see
`freq`

.

**Data Types: **`single`

| `double`

## Output Arguments

`freq`

— Frequencies

vector

Frequencies at which the short-time FFT is computed, returned as a column vector.

The length of the frequency vector is determined by the FrequencyRange property and the FFTLength.

If you set `FrequencyRange`

to
`'onesided'`

and `FFTlength`

is even, the
frequency vector is of length `(`

.
If you set the `FFTlength`

/2)+1`FrequencyRange`

to `'onesided'`

and
`FFTlength`

is odd, the frequency vector is of length
`(`

.`FFTlength`

+1)/2

The frequencies cover the interval [0, `Fs`

/2]. When
`Fs`

is not specified, the frequencies range from [0, π].

If you set the `FrequencyRange`

property to `'twosided'`

, the length of the frequency vector is equal
to the value you specify in the `FFTlength`

property. The frequencies
cover the interval [0, `Fs`

]. When `Fs`

is not
specified, the frequencies range from [0, 2π].

**Data Types: **`single`

| `double`

## Extended Capabilities

### C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

## Version History

**Introduced in R2020b**

## See Also

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