# downsample

Decrease sample rate by integer factor

## Syntax

``y = downsample(x,n)``
``y = downsample(x,n,phase)``

## Description

example

````y = downsample(x,n)` decreases the sample rate of `x` by keeping the first sample and then every `n`th sample after the first. If `x` is a matrix, the function treats each column as a separate sequence.```
````y = downsample(x,n,phase)` specifies the number of samples by which to offset the downsampled sequence.```

## Examples

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Decrease the sample rate of a sequence by a factor of 3.

```x = [1 2 3 4 5 6 7 8 9 10]; y = downsample(x,3)```
```y = 1×4 1 4 7 10 ```

Decrease the sample rate of the sequence by a factor of 3 and add a phase offset of 2.

`y = downsample(x,3,2)`
```y = 1×3 3 6 9 ```

Decrease the sample rate of a matrix by a factor of 3.

```x = [1 2 3; 4 5 6; 7 8 9; 10 11 12]; y = downsample(x,3)```
```y = 2×3 1 2 3 10 11 12 ```

## Input Arguments

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Input array, specified as a vector or matrix. If `x` is a matrix, the function treats the columns as independent channels.

Example: `cos(pi/4*(0:159)) + randn(1,160)` specifies a sinusoid embedded in white Gaussian noise.

Example: `cos(pi./[4;2]*(0:159))' + randn(160,2)` specifies a two-channel noisy sinusoid.

Downsampling factor, specified as a positive integer.

Data Types: `single` | `double`

Offset, specified as a positive integer from 0 to `n` – 1.

Data Types: `single` | `double`

## Output Arguments

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Downsampled array, returned as a vector or matrix.