# size

Determine size of `iddata` data set

## Syntax

``[ns,ny,nu,ne] = size(data)``
``sd = size(data)``
``ns = size(data,1)``
``ny = size(data,2)``
``nu = size(data,3)``
``ne = size(data,4)``
``size(data)``

## Description

### Return All Size Information

````[ns,ny,nu,ne] = size(data)` returns, for the `iddata` object `data`, the number of data samples `ns` in each experiment, the number of outputs `ny`, the number of inputs `nu`, and the number of experiments `ne`.```

example

````sd = size(data)` returns the size information in the single argument `sd`. For single experiments, `sd` has the form [`ns`,`ny`,`nu`,`ne`].For multiple experiments, `sd` has the form [`sum`(`ns`),`ny`,`nu`,`ne`]. Here, `sum`(`ns`) is the total number of sample points from all the experiments. ```

example

### Return Single Size Variable

````ns = size(data,1)` returns the number of data samples in each experiment.```
````ny = size(data,2)` returns the number of output channels.```
````nu = size(data,3)` returns the number of input samples.```
````ne = size(data,4)` returns the number of experiments.```

### Display Size Information

````size(data)` displays the size information.```

## Examples

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Load the data, which is an `iddata` object that contains input/output data for three experiments.

```load z123merge.mat z123 data = z123;```

Get and store the dimensions of `data` in four separate variables.

`[ns,ny,nu,ne] = size(data)`
```ns = 1×3 300 400 300 ```
```ny = 1 ```
```nu = 1 ```
```ne = 3 ```

Get and store the dimensions of `data` in a single variable.

`sd = size(data)`
```sd = 1×4 1000 1 1 3 ```

The first element of `sd` is the total number of samples in the three experiments.

## Input Arguments

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Estimation input/output data, specified as an `iddata` object that can contain any number of samples, input channels, output channels, and experiments.

## Output Arguments

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Number of samples in each experiment of `data`, returned as row vector of positive integers with length `ne`.

Number of output channels in `data`, returned as a positive integer.

Number of input channels in `data`, returned as a positive integer.

Number of experiments in `data`, returned as a positive integer.

Combined size information, returned as a row vector containing the numbers of samples, output channels, input channels, and experiments.

• For single experiments, `sd` has the form [`ns`,`ny`,`nu`,`ne`].

• For multiple experiments, `sd` has the form [`sum`(`ns`),`ny`,`nu`,`ne`]. Here, `sum`(`ns`) is the total number of sample points from all the experiments.

## Version History

Introduced in R2006a