# 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 Pair Arguments

'Method'

Discretization method, specified as one of the following values:

 'zoh' Zero-order hold, where d2d assumes 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.

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

Resample a discrete-time model using the 'tustin' method with frequency prewarping.

Create the discrete-time transfer function

$\frac{z+1}{{z}^{2}+z+1}$

h1 = tf([1 1], [1 1 1], 0.1);  % 0.1s sample time
To resample to a different sample time, use d2dOptions to create the option set.

opts = d2dOptions('Method', 'tustin', 'PrewarpFrequency', 20);
h2 = d2d(h1, 0.05, opts);

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