# initialplot

Plot initial condition response and return plot handle

## Syntax

```initialplot(sys,x0) initialplot(sys,x0,Tfinal) initialplot(sys,x0,t) initialplot(sys1,sys2,...,sysN,x0) initialplot(sys1,sys2,...,sysN,x0,Tfinal) initialplot(sys1,sys2,...,sysN,x0,t) initialplot(AX,...) initialplot(..., plotoptions) h = initialplot(...) ```

## Description

`initialplot(sys,x0)` plots the undriven response of the state-space (`ss`) model `sys` with initial condition `x0` on the states. This response is characterized by these equations:

Continuous time: x = A x, y = C x, x(0) = x0

Discrete time: x[k+1] = A x[k], y[k] = C x[k], x = x0

The time range and number of points are chosen automatically. `initialplot` also returns the plot handle `h`. You can use this handle to customize the plot with the `getoptions` and `setoptions` commands. Type

```help timeoptions ```

for a list of available plot options.

`initialplot(sys,x0,Tfinal)` simulates the response from `t = 0` to the final time ```t = Tfinal```. Express `Tfinal` in the system time units, specified in the `TimeUnit` property of `sys`. For discrete-time systems with unspecified sample time (`Ts = -1`), `initialplot` interprets `Tfinal` as the number of sampling periods to simulate.

`initialplot(sys,x0,t)` uses the user-supplied time vector `t` for simulation. Express `t` in the system time units, specified in the `TimeUnit` property of `sys`. For discrete-time models, `t` should be of the form `0:Ts:Tf`, where `Ts` is the sample time. For continuous-time models, `t` should be of the form `0:dt:Tf`, where `dt` becomes the sample time of a discrete approximation to the continuous system (see `impulse`).

To plot the initial condition responses of several LTI models on a single figure, use

`initialplot(sys1,sys2,...,sysN,x0)`

`initialplot(sys1,sys2,...,sysN,x0,Tfinal)`

`initialplot(sys1,sys2,...,sysN,x0,t)`

You can also specify a color, line style, and marker for each system, as in

```initialplot(sys1,'r',sys2,'y--',sys3,'gx',x0). ```

`initialplot(AX,...)` plots into the axes with handle `AX`.

`initialplot(..., plotoptions)` plots the initial condition response with the options specified in `plotoptions`. Type

```help timeoptions ```

for more detail.

`h = initialplot(...)` plots the system response and returns the plot handle `h`.

## Examples

Plot a third-order system's response to initial conditions and use the plot handle to change the plot's title.

```sys = rss(3); h = initialplot(sys,[1,1,1]) p = getoptions(h); % Get options for plot. p.Title.String = 'My Title'; % Change title in options. setoptions(h,p); % Apply options to the plot. ```

## Tips

You can change the properties of your plot, for example the units. For information on the ways to change properties of your plots, see Ways to Customize Plots.