# d2dOptions

Create option set for discrete-time resampling

## Syntax

```opts = d2dOptions opts = d2dOptions('OptionName', OptionValue) ```

## Description

`opts = d2dOptions` returns the default options for `d2d`.

`opts = d2dOptions('OptionName', OptionValue)` accepts one or more comma-separated name-value pairs that specify options for the `d2d` command. Specify `OptionName` inside single quotes.

This table summarizes the options that the `d2d` command supports.

## Input Arguments

### Name-Value Arguments

`Method`

Discretization method, specified as one of the following values:

 `'zoh'` Zero-order hold, where `d2d` assumes that the control inputs are piecewise constant over the sample time `Ts`. `'tustin'` Bilinear (Tustin) approximation. By default, `d2d` resamples with no prewarp. To include prewarp, use the `PrewarpFrequency` option.

For information about the algorithms for each `d2d` conversion method, see Continuous-Discrete Conversion Methods.

Default: `'zoh'`

`PrewarpFrequency`

Prewarp frequency for `'tustin'` method, specified in `rad/TimeUnit`, where `TimeUnit` is the time units, specified in the `TimeUnit` property, of the resampled system. Takes positive scalar values. The prewarp frequency must be smaller than the Nyquist frequency before and after resampling. A value of 0 corresponds to the standard `'tustin'` method without prewarp.

Default: 0

## Examples

collapse all

Create the following discrete-time transfer function with sample time 0.1 seconds.

`$H\left(z\right)=\frac{z+1}{{z}^{2}+z+1}$`

`h1 = tf([1 1],[1 1 1],0.1);`

Specify the discretization method as bilinear Tustin method with a prewarping frequency of 20 rad/seconds.

`opts = d2dOptions('Method','tustin','PrewarpFrequency',20);`

Resample the discrete-time model using the specified options.

`h2 = d2d(h1,0.05,opts);`

You can use the option set `opts` to resample additional models using the same options.

## Version History

Introduced in R2010a