Simulink Functions Overview - MATLAB & Simulink (2024)

• Simulink Function block —Function defined using Simulink blocks within a Simulink Function block.

• Exported Stateflow^® graphical function — Function defined with statetransitions within a Stateflow chart, and then exported to a Simulink model.

• Exported StateflowMATLAB function — Function defined with MATLAB language statements within a Stateflow chart, and then exported to a Simulink model.

• S-function — Function defined using anS-function block. For an example with an S-function, opensfcndemo_simulinkfunction_getset.

• Function Caller block — Calla function defined in Simulink or exported from Stateflow. See FunctionCaller.

• Stateflow chart transition — In a Stateflow chart, call a function defined in Simulink or exported from Stateflow.

• MATLAB Function block — Call a function from a MATLAB language script.

• S-Function block — Call a function usingsystem methods. See ssDeclareFunctionCaller and ssCallSimulinkFunction.

• MATLAB System block — Call a function using aSystem object™ and the MATLAB language.

Note

Input and output argument names (x2, y2) forcalling a function from a Stateflow chart do not have to match the argument names in the function prototype(u, y) of a Simulink Function block.

mySignal = filter(mySignal)

void filter(real_T *rtuy_mySignal){. . .

*rtuy_mySignal = model_P.DiscreteFilter_NumCoef * DiscreteFilter_tmp; }

• The arguments in the Function prototype parameter for aFunction Caller block matches the arguments specified in the function.For example, a function with two input arguments and one output argument appearsas:

  y = MyFunction(u1, u2)

• The data type, dimension, and complexity of the arguments must agree. For aFunction Caller block, you can set the Input argumentspecifications and Output argument specificationsparameters, but usually you do not need to specify these parameters manually.Simulink derives the specification from thefunction.

  The only case where you must specify the argument parameters is when theFunction Caller block cannot find the function in the model or in anychild model it references. This situation can happen when the FunctionCaller block and called function are in separate models that are referenced bya common parent model. See Simulink Function Blocks in Referenced Modelsand Argument Specification for Simulink Function Blocks.

• Eliminate routing of signal lines. TheFunction Caller block allows you to execute functions defined with aSimulink Function block without a connecting signal line. In addition,functions and their callers can reside in different models or subsystems. This approacheliminates signal routing problems through a hierarchical model structure and allowsgreater reuse of model components.

• Use multiple callers to the same function. MultipleFunction Caller blocks or Stateflow charts can call the same function. If the function contains state (forexample, a Unit Delay block), the state is shared between the differentcallers.

• Separate function interface from functiondefinition. Functions separate their interface (input and output arguments)from their implementation. Therefore, you can define a function using a SimulinkFunction block, an exported graphical function from Stateflow, or an exported MATLAB function from Stateflow. The caller does not need to know how or where the function wasimplemented.

• For a Simulink Function block, when one block has multiple callers,code is always generated for one function. If the Simulink Function blockcontains blocks with state (for example, Delay or Memory),the state is persistent and shared between function callers. In this case, the order ofcalls is an important consideration.

• For a Subsystem block, when a block has multiple instances and isconfigured as a reusable function, code is usually generated for one function as anoptimization. If the Subsystem block contains blocks with state, code isstill generated for one function, but a different state variable is passed to thefunction. State is not shared between theinstances.

  See Also

  S-Function Examples - MATLAB & Simulink

• Persistence of state between function calls. If aSimulink Function block contains any blocks with state (for example,Unit Delay or Memory), then their state values arepersistent between calls to the function. If there are multiple calls to that function,the state values are also persistent between the calls originating from differentcallers.

• Inheriting continuous sample time. ASimulink Function block cannot inherit a continuous sample time.Therefore, do not use this block in systems that use continuous sample times to modelcontinuous systemequations.

• Turning on/off tracing lines — On the Debugtab, under Information Overlays, click Connectors.Select Function Connectors option from theConnectors pane that appears on the Simulinkcanvas.

• Direction of tracing lines — Lines connected at the bottom of a block arefrom a function caller. Lines connected at the top of a block are to a Simulink function or a subsystem containing the function.

  

  

• Navigation to functions — A function caller can be within a subsystem.

  

  Navigate from a caller in a subsystem to a function by first opening the subsystem,and then clicking a link to the function.

  

  If the function is at the root level of a model, the function opens. If the functionis within a subsystem, the subsystem containing the function opens.