C/C++ S-Function Basics

Learn the basics of S-functions

An S-function is a computer language description of a Simulink^® block written in MATLAB^®, C, C++, or Fortran^®. C, C++, and Fortran S-functions are compiled as MEX files using the mex utility. See Build C MEX Function. As with other MEX files, S-functions are dynamically linked subroutines that the MATLAB execution engine can automatically load and execute.

You can implement your S-functions using one of these ways:

Level-2 MATLAB S-function - Provides access to a more extensive set of the S-function API and supports code generation.
C MEX S-function - Enables you to implement your algorithm as a C MEX S-function or write a wrapper S-function to call existing C, C++, or Fortran code.
The S-Function Builder - Provides a graphical user interface that is used to generate new S-functions or incorporate existing C or C++ code without interacting with the S-function API.
The Legacy Code Tool - Provides a set of MATLAB commands that helps you create an S-function to incorporate legacy C or C++ code.

Topics

What Is an S-Function?
Learn how S-functions work.
Create and Implement a Basic C MEX S-Function
Construct the code to create an S-function.
S-Function Concepts
Learn key concepts needed to write different types of S-functions.
S-Function Callback Methods
Implement S-function callback methods.
S-Function Features and Limitations
Compare and contrast features supported by different types of S-function implementations.