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Function Definition

Defining and calling for code acceleration

There are special considerations when you create MATLAB® functions that are intended for fixed-point acceleration. 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.ignoreConst (MATLAB Coder). While generating a MEX function, 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.


coder.extrinsicDeclare function as extrinsic and execute it in MATLAB
coder.ignoreConstPrevent use of constant value of expression for function specializations
coder.mustBeConstValidate that value is a compile-time constant (Since R2023b)
coder.unrollUnroll for-loop by making a copy of the loop body for each loop iteration
coder.sameSizeBinaryOpApply element-wise binary operations without implicit expansion (Since R2021b)
coder.noImplicitExpansionInFunctionDisable implicit expansion within the specified function in the generated code (Since R2021b)
coder.readRead data files at run time in generated code (Since R2023a)
coder.writeCreate data files that the generated code reads at run time (Since R2023a)



Nonconstant Index into varargin or varargout in a for-Loop

Force loop unrolling when the code generator cannot determine the value of the index into varargin or varargout.

Output Variable Must Be Assigned Before Run-Time Recursive Call

Troubleshoot output variable assignment for run-time recursion.

Compile-Time Recursion Limit Reached

Troubleshoot compile-time recursion limit error.