LTI Models (Creating and Manipulating Models)

Creating and Manipulating Models

Generic Properties

The generic properties are those shared by all four types of LTI models (TF, ZPK, SS, and FRD objects). They are listed in the table below.

Table 1-4: Generic LTI Properties
Property Name
Description
Property Value

ioDelay
I/O delay(s)
Matrix

InputDelay
Input delay(s)
Vector

InputGroup
Input channel groups
Cell array

InputName
Input channel names
Cell vector of strings

Notes
Notes on the model history
Text

OutputDelay
Output delay(s)
Vector

OutputGroup
Output channel groups
Cell array

OutputName
Output channel names
Cell vector of strings

Ts
Sample time
Scalar

Userdata
Additional data
Arbitrary

**Table 1-4: Generic LTI Properties**
Property Name	Description	Property Value
`ioDelay`	I/O delay(s)	Matrix
`InputDelay`	Input delay(s)	Vector
`InputGroup`	Input channel groups	Cell array
`InputName`	Input channel names	Cell vector of strings
`Notes`	Notes on the model history	Text
`OutputDelay`	Output delay(s)	Vector
`OutputGroup`	Output channel groups	Cell array
`OutputName`	Output channel names	Cell vector of strings
`Ts`	Sample time	Scalar
`Userdata`	Additional data	Arbitrary

The sample time property Ts keeps track of the sample time (in seconds) of discrete-time systems. By convention, Ts is 0 (zero) for continuous-time systems, and Ts is -1 for discrete-time systems with unspecified sample time. Ts is always a scalar, even for MIMO systems.

The InputDelay, OutputDelay, and ioDelay properties allow you to specify time delays in the input or output channels, or for each input/output pair. Their default value is zero (no delay). See Time Delays for details on modeling delays.

The InputName and OutputName properties enable you to give names to the individual input and output channels. The value of each of these properties is a cell vector of strings with as many cells as inputs or outputs. For example, the OutputName property is set to

```
{ 'temperature' ; 'pressure' }
```

for a system with two outputs labeled temperature and pressure. The default value is a cell of empty strings.

Using the InputGroup and OutputGroup properties of LTI objects, you can create different groups of input or output channels, and assign names to the groups. For example, you may want to designate the first four inputs of a five-input model as controls, and the last input as noise. See Input Groups and Output Groups for more information.

Finally, Notes and Userdata are available to store additional information on the model. The Notes property is dedicated to any text you want to supply with your model, while the Userdata property can accommodate arbitrary user-supplied data. They are both empty by default.

For more detailed information on how to use LTI properties, see Additional Insight into LTI Properties.

LTI Properties Model-Specific Properties