matlab.System class

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 methods 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.

The matlab.System class is a handle class.

Class Attributes

Abstract	true
HandleCompatible	true
StrictDefaults	false

For information on class attributes, see Class Attributes.

Methods

Specialized Operators and Functions

These methods specialize standard MATLAB^® operators and functions for objects of this class.

nargin	Number of input arguments
nargout	Number of output arguments

Protected Methods

Initialize, Run, Reset

setupImpl	Initialize System object
stepImpl	System output and state update equations
resetImpl	Reset System object states
releaseImpl	Release resources

Properties and States

getDiscreteStateImpl	Discrete state property values
infoImpl	Information about System object
isDoneImpl	End-of-data flag
isInactivePropertyImpl	Status of inactive property
isTunablePropertyDataTypeMutableImpl	Set whether tunable properties can change data type
isDiscreteStateSpecificationMutableImpl	Control whether discrete states can change data type
processTunedPropertiesImpl	Action when tunable properties change
setProperties	Set property values using name-value pairs when creating System object
validatePropertiesImpl	Validate property values of System object

Input and Output

getNumInputsImpl	Number of inputs to the System object
getNumOutputsImpl	Number of outputs from System object
getNumInputs	Number of inputs required to call the System object
getNumOutputs	Number of outputs from calling the System object
getInterfaceImpl (Simulink)	Set System object as message or data
isInputComplexityMutableImpl	Set whether System object input complexity can change
isInputDataTypeMutableImpl	Set whether System object input data type can change
isInputSizeMutableImpl	Set whether System object input size can change
nargin	Number of input arguments for System object
nargout	Number of output arguments for System object
processInputSpecificationChangeImpl	Perform actions when input size, complexity, or data type change
validateInputsImpl	Validate inputs to System object

Load and Save

loadObjectImpl	Load System object from MAT file
saveObjectImpl	Save System object in MAT file

MATLAB System Block Support

allowModelReferenceDiscreteSampleTimeInheritanceImpl	Model reference sample time inheritance status for discrete sample times
getSimulateUsingImpl	Specify value for Simulate using parameter
getSimulinkFunctionNamesImpl	Register Simulink function names used in your System object
showFiSettingsImpl	Fixed point data type tab visibility for System objects
supportsMultipleInstanceImpl	Support System object in Simulink For Each subsystem
getSimulateUsingImpl	Specify value for Simulate using parameter
supportsMultipleInstanceImpl	Support System object in Simulink For Each subsystem

Simulink Nondirect Feedthrough

isInputDirectFeedthroughImpl	Direct feedthrough status of input
outputImpl	Output calculation from input or internal state of System object
updateImpl	Update object states based on inputs

Simulink Propagation

getDiscreteStateSpecificationImpl	Discrete state size, data type, and complexity
getOutputDataTypeImpl	Data types of output ports
getOutputSizeImpl	Sizes of output ports
isOutputComplexImpl	Complexity of output ports
isOutputFixedSizeImpl	Fixed- or variable-size output ports
propagatedInputComplexity	Complexity of input during Simulink propagation
propagatedInputDataType	Data type of input during Simulink propagation
propagatedInputFixedSize	Fixed-size status of input during Simulink propagation
propagatedInputSize	Size of input during Simulink propagation

MATLAB System Block Appearance Customization

getIconImpl	Name to display as block icon
getHeaderImpl	Header for System object display
matlab.system.display.Action	Custom button
matlab.system.display.Header	Header for System objects properties
matlab.system.display.Icon	Custom icon image
matlab.system.display.Section	Property group section for System objects
matlab.system.display.SectionGroup	Section group for System objects
getInputNamesImpl	Names of MATLAB System block input ports
getOutputNamesImpl	Names of MATLAB System block output ports
getGlobalNamesImpl	Global variable names for MATLAB System block
showSimulateUsingImpl	Visibility of Simulate using parameter

Simulink Sample Time

createSampleTime	Create sample time specification object
getSampleTime	Query sample time
getSampleTimeImpl	Specify sample time type, offset time, and sample time
getCurrentTime	Current simulation time in MATLAB System block
allowModelReferenceDiscreteSampleTimeInheritanceImpl	Model reference sample time inheritance status for discrete sample times

Simulink Dataflow

getImpulseResponseLengthImpl	Define length of input effects for dataflow subsystems
getInputDimensionConstraintImpl	Define input dimension constraints for dataflow subsystems
getOutputDimensionConstraintImpl	Define output dimension constraints for dataflow subsystems

Examples

Create Basic System Object

This example shows how to author a basic System object called AddOne.

In MATLAB, select New > System object > Basic. A new editor window opens with default syntax and comments for a new System object.

Rename the class AddOne. Modify the default template so your class looks like this:

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

    methods (Access = protected)
       % Implement algorithm. Calculate y as a function of input x.
       function y = stepImpl(~,x)
          y = x + 1;
       end    
    end
end

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

addingObject = AddOne;
x = 5;
addingObject(x)

ans = 6

More About

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 changes to a 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.

DiscreteState

Use DiscreteState to mark a property so it will display its state value when you use the getDiscreteState method.