# Documentation

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# dss

Create descriptor state-space models

## Syntax

`sys = dss(A,B,C,D,E) sys = dss(A,B,C,D,E,Ts) sys = dss(A,B,C,D,E,ltisys)`

## Description

`sys = dss(A,B,C,D,E) ` creates the continuous-time descriptor state-space model

`$\begin{array}{c}E\frac{dx}{dt}=Ax+Bu\\ y=Cx+Du\end{array}$`

The output `sys` is an SS model storing the model data (see State-Space Models). Note that `ss` produces the same type of object. If the matrix D = 0, you can simply set `d` to the scalar `0` (zero).

`sys = dss(A,B,C,D,E,Ts) ` creates the discrete-time descriptor model

`$\begin{array}{c}Ex\left[n+1\right]=Ax\text{\hspace{0.17em}}\left[n\right]+Bu\text{\hspace{0.17em}}\left[n\right]\\ y\text{\hspace{0.17em}}\left[n\right]=Cx\text{\hspace{0.17em}}\left[n\right]+Du\text{\hspace{0.17em}}\left[n\right]\end{array}$`

with sample time `Ts` (in seconds).

`sys = dss(A,B,C,D,E,ltisys)` creates a descriptor model with properties inherited from the LTI model `ltisys` (including the sample time).

Any of the previous syntaxes can be followed by property name/property value pairs

```'Property',Value ```

Each pair specifies a particular LTI property of the model, for example, the input names or some notes on the model history. See `set` and the example below for details.

## Examples

The command

```sys = dss(1,2,3,4,5,'inputdelay',0.1,'inputname','voltage',... 'notes','Just an example'); ```

creates the model

`$\begin{array}{c}5\stackrel{˙}{x}=x+2u\\ y=3x+4u\end{array}$`

with a 0.1 second input delay. The input is labeled `'voltage'`, and a note is attached to tell you that this is just an example.