Function Definition
R2026bThere are special considerations when you create MATLAB® functions that are intended for use in a MATLAB
Function block. These include certain restrictions when you use
varargin and varargout, recursive
functions, anonymous functions, and nested functions. To generate code for
MATLAB recursive functions, the code generator uses either compile-time
recursion or run-time recursion. To produce efficient C/C++ code, the code
generator sometimes creates multiple versions of a function, referred to as
function specializations. In certain cases, you can prevent the code generator
from creating function specializations by using coder.ignoreSize and coder.ignoreConst. You can bypass
code generation for a specific function in your MATLAB code and instead use the MATLAB engine to execute the call. To do this, use the coder.extrinsic construct.
Blocks
 | MATLAB Function | Include MATLAB code in Simulink models |
 | MATLAB System | Include System object in model |
Functions
coder.extrinsic | Declare extrinsic function |
coder.ignoreSize | Prevent code generator from creating function specializations for constant-size expressions |
coder.ignoreConst | Prevent use of constant value of expression for function specializations |
coder.mustBeConst | Validate that value is a compile-time constant (Since R2023b) |
coder.unroll | Unroll for-loop by making a copy of
the loop body for each loop iteration |
coder.sameSizeBinaryOp | Apply element-wise binary operations without implicit expansion |
coder.noImplicitExpansionInFunction | Disable implicit expansion within the specified function in the generated code |
coder.read | Read data files at run time in generated code (Since R2023a) |
coder.write | Create data files that the generated code reads at run time (Since R2023a) |
Topics
- Effects of Implicit Expansion on Generated Code (MATLAB Coder)
Implicit expansion in the generated code can affect output sizes, code size, and performance.
- Control Implicit Expansion in Generated Code (MATLAB Coder)
Disable implicit expansion globally, for specific functions, or for specific operations.
- Generate Code for arguments Block That Validates Input and Output Arguments (MATLAB Coder)
Generate code for MATLAB code that constrains class, size, and other aspects of function input and output values.
- Code Generation for Recursive Functions (MATLAB Coder)
Use recursive functions in MATLAB code that is intended for code generation.
- Code Generation for Nested and Anonymous MATLAB Functions (MATLAB Coder)
Restrictions apply when you use nested or anonymous functions in MATLAB code intended for code generation.
- Using Extrinsic Functions (MATLAB Coder)
Use MATLAB to execute a function call in the generated code.
- Working With mxArray Outputs in Generated Code (MATLAB Coder)
Handle the
mxArrayobjects returned by extrinsic functions.
Troubleshooting
Resolve Error: Nonconstant Index into varargin or varargout (MATLAB Coder)
Troubleshoot error when the code generator cannot determine the value of an index
into varargin or varargout inside a
for-loop.
Troubleshoot Replicated Functions in Generated Code (MATLAB Coder)
Troubleshoot duplicate functions in the generated code.
Resolve Error: Output Variable Must Be Assigned Before Run-Time Recursive Call (MATLAB Coder)
Troubleshoot error when the MATLAB code does not assign a value to an output variable before a recursive call.
Resolve Error: Compile-Time Recursion Limit Reached (MATLAB Coder)
Troubleshoot error when recursion during code generation exceeds the limit.
Resolve Error: Arrays Have Incompatible Sizes (MATLAB Coder)
Troubleshoot size incompatibility errors that occur during code generation.
