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Class: matlab.System

Initialize System object




setupImpl(obj) implements one-time tasks.

setupImpl(obj,input1,input2,...) sets up a System object™ using one or more of the stepImpl input specifications.

Run-Time Details

setupImpl is called via the setup method. Users never call the setup method directly. But, setup is called the first time a System object is run and after a System object has been released. For details, see Detailed Call Sequence

Method Authoring Tips

  • If your System object does not require any setup tasks, you can omit this method from your class definition file.

  • Use setupImpl to set private properties so they do not need to be calculated each time stepImpl method is called.

  • To acquire resources for a System object, you must use setupImpl instead of a constructor.

  • You must set Access = protected for this method.

  • Do not use setupImpl to initialize or reset states. For states, use the resetImpl method.

  • If the System object will be used in the Simulink® MATLAB System (Simulink) block, you cannot modify any tunable properties in the setupImpl method

  • Do not use the setupImpl method to set up input values.

  • Do not include validation in setupImpl. To validate properties or inputs use the validatePropertiesImpl, validateInputsImpl, or setProperties methods.

  • Do not use the input values of the System object in this method if you intend to use the System object in Simulink using the MATLAB System (Simulink) block. You can only query the inputs for their specifications namely data type, complexity and size.

Input Arguments

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System object handle used to access properties, states, and methods specific to the object. If your setupImpl method does not use the object, you can replace this input with ~.

List the inputs to the System object. The order of inputs must match the order of inputs defined in the stepImpl method. stepImpl passes the inputs into setupImpl to use the specifications, such as size and data types in the one-time calculations.


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This example shows how to open a file for writing using the setupImpl method in your class definition file.

methods (Access = protected)
   function setupImpl(obj)
      obj.pFileID = fopen(obj.Filename,'wb');
      if obj.pFileID < 0
         error('Opening the file failed');

Filename should be defined as a nontunable property of the System object

properties (Nontunable)
   Filename = "default.bin"

This example shows how to use setupImpl to specify that running the object initializes the properties of an input. In this case, calls to run the object, which includes input u, initialize the object states in a matrix of size u.

methods (Access = protected)
   function setupImpl(obj, u) 
    obj.State = zeros(size(u),'like', u); 

Version History

Introduced in R2011b