matlab.System class

Package: matlab

Base class for System objects

Description

matlab.System is the base class for System objects. In your class definition file, you must subclass your object from this base class (or from another class that derives from this base class). Subclassing allows you to use the implementation and service methods provided by this base class to build your object. Type this syntax as the first line of your class definition file to directly inherit from the matlab.System base class, where ObjectName is the name of your object:

classdef ObjectName < matlab.System

Note

You must set Access = protected for each matlab.System method you use in your code.

Methods

allowModelReferenceDiscreteSampleTimeInheritanceImpl	Model reference sample time inheritance status for discrete sample times
getDiscreteStateImpl	Discrete state property values
getGlobalNamesImpl	Global variable names for MATLAB System block
getHeaderImpl	Header for System object display
getImpulseResponseLengthImpl	Define length of input effects for dataflow subsystems
getInputDimensionConstraintImpl	Define input dimension constraints for dataflow subsystems
getInputNamesImpl	Names of MATLAB System block input ports
getNumInputsImpl	Number of inputs to the System object
getNumOutputsImpl	Number of outputs from System object
getOutputDimensionConstraintImpl	Define output dimension constraints for dataflow subsystems
getOutputNamesImpl	Names of MATLAB System block output ports
getPropertyGroupsImpl	Property groups for System object display
getSimulateUsingImpl	Specify value for Simulate using parameter
infoImpl	Information about System object
isDiscreteStateSpecificationMutableImpl	Control whether discrete states can change data type
isInactivePropertyImpl	Status of inactive property
isInputComplexityMutableImpl	Set whether System object input complexity can change
isInputDataTypeMutableImpl	Set whether System object input data type can change
isInputSizeLockedImpl	Status of locked input size
isInputSizeMutableImpl	Set whether System object input size can change
isTunablePropertyDataTypeMutableImpl	Set whether tunable properties can change data type
loadObjectImpl	Load System object from MAT file
processInputSpecificationChangeImpl	Perform actions when input size, complexity, or data type change
processTunedPropertiesImpl	Action when tunable properties change
releaseImpl	Release resources
resetImpl	Reset System object states
saveObjectImpl	Save System object in MAT file
setProperties	Set property values using name-value pairs when creating System object
setupImpl	Initialize System object
showFiSettingsImpl	Fixed point data type tab visibility for System objects
showSimulateUsingImpl	Visibility of Simulate using parameter
stepImpl	System output and state update equations
supportsMultipleInstanceImpl	Support System object in Simulink For Each subsystem
validateInputsImpl	Validate inputs to System object
validatePropertiesImpl	Validate property values of System object

Attributes

You can apply attributes to the System object™ class and properties. To learn more about attributes, see Class Attributes or Property Attributes.

Class Attribute

This table shows attributes that you can apply to the MATLAB^® System object class.

Attribute Name

Description

StrictDefaults

Control the defaults for the methods that restrict specification modifications changes: isInputSizeMutableImpl isInputComplexityMutableImpl isInputDataTypeMutableImpl isTunablePropertyDataTypeMutableImpl isDiscreteStateDataTypeMutableImpl By default, these methods return true. When you add this class attribute, these methods return false by default. By making these methods return false, the specified aspects of the inputs, tunable properties, or discrete states cannot change. You can always implement these methods individually. Customized methods take precedence over the StrictDefaults attribute. For System objects used in Simulink®, this attribute only restricts input size changes because Simulink already restricts complexity and data type for tunable properties, inputs, and states.

Specify the class attribute value in parentheses followed by the class name, for example:

classdef (StrictDefaults) MySystemObject < matlab.System

Property Attributes

You can apply the following attributes to any property of a custom System object.

Nontunable	Use Nontunable to prevent a user from changing that property value while the object is in use. By default, all properties are tunable. The Nontunable attribute is useful to lock down a property that has side effects when changed. This attribute is also useful for locking a property value assumed to be constant during processing. You should always specify properties that affect the number of input or output ports as Nontunable.
Logical	Use Logical to limit the property value to a logical, scalar value. Any scalar value that can be converted to a logical is also valid, such as 0 or 1.
PositiveInteger	Use PositiveInteger to limit the property value to a positive integer value.
DiscreteState	Use DiscreteState to mark a property so it will display its state value when you use the getDiscreteState method.

Examples

Create a Basic System Object

Create a simple System object, AddOne, which subclasses from matlab.System. You place this code into a MATLAB file, AddOne.m.

classdef AddOne < matlab.System
% ADDONE Compute an output value that increments the input by one

    methods (Access = protected)
       % stepImpl method is called when the object is called.
       function y = stepImpl(~,x)
          y = x + 1;
       end    
    end
end

Use this object by creating an instance of AddOne, providing an input, and running the object.

hAdder = AddOne;
x = 1;
hAdder(x);

Assign the Nontunable attribute to the InitialValue property, which you define in your class definition file.

properties (Nontunable)
   InitialValue
end