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User-Defined Functions

Custom function blocks such as MATLAB Function, MATLAB System, Simulink Function, and Initialize Function

Use blocks from the User-Defined Functions library to extend Simulink® modeling functionality by creating new types of blocks. You can implement block algorithms using MATLAB®, C/C++, and Fortran® code.

Blocks

C CallerIntegrate C code in Simulink
C FunctionIntegrate and call external C/C++ code from a Simulink model
FcnApply specified expression to input
Function CallerCall a Simulink function
Initialize FunctionExecute subsystem on model initialize event
Interpreted MATLAB Function(To be removed) Apply MATLAB function or expression to input
Level-2 MATLAB S-FunctionUse Level-2 MATLAB S-function in model
MATLAB FunctionInclude MATLAB code in Simulink models
MATLAB SystemInclude System object in model
Python CodeIntegrate native Python code into a Simulink model (Since R2025a)
Reinitialize FunctionExecute subsystem on model or subsystem reinitialize event (Since R2022a)
Reset FunctionExecute subsystem on model reset event
S-FunctionInclude S-function in model
S-Function BuilderIntegrate C or C++ code to create S-functions
Simulink FunctionDefine a function using Simulink blocks
Terminate FunctionExecute subsystem on model terminate event