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# d2cOptions

Create option set for discrete- to continuous-time conversions

## Syntax

opts = d2cOptions
opts = d2cOptions(Name,Value)

## Description

opts = d2cOptions returns the default options for d2c.

opts = d2cOptions(Name,Value) creates an option set with the options specified by one or more Name,Value pair arguments.

## Input Arguments

### Name-Value Pair Arguments

'method'

Discretization method, specified as one of the following values:

 'zoh' Zero-order hold, where d2c assumes the control inputs are piecewise constant over the sampling period Ts. 'foh' Linear interpolation of the inputs (modified first-order hold). Assumes the control inputs are piecewise linear over the sampling period. 'tustin' Bilinear (Tustin) approximation. By default, d2c converts with no prewarp. To include prewarp, use the PrewarpFrequency option. 'matched' Zero-pole matching method. (See [1], p. 224.)

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 discrete-time system. Specify the prewarp frequency as a positive scalar value. A value of 0 corresponds to the 'tustin' method without prewarp.

Default: 0

## Examples

Convert a discrete-time model to continuous-time using the 'tustin' method with frequency prewarping.

Create the discrete-time transfer function

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

`hd = tf([1 1], [1 1 1], 0.1);  % 0.1s sampling time`

To convert to continuous-time, use d2cOptions to create the option set.

```opts = d2cOptions('Method', 'tustin', 'PrewarpFrequency', 20);
hc = d2c(hd, opts);```

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

## References

[1] Franklin, G.F., Powell,D.J., and Workman, M.L., Digital Control of Dynamic Systems (3rd Edition), Prentice Hall, 1997.