Documentation

When you use varargin and varargout for code generation, adhere to these restrictions:

• You cannot use varargout in the function definition for a top-level function.

• You cannot use varargin in the function definition for a top-level function in a MATLAB Function block in a Simulink^® model, or in a MATLAB^® function in a Stateflow^® diagram.

• If you use varargin to define an argument to a top-level function, the code generator produces the function with a fixed number of arguments. This fixed number of arguments is based on the number of example arguments that you provide on the command line or in a MATLAB Coder™ project test file.

A top-level function is:

• The function called by Simulink in a MATLAB Function block or by Stateflow in a MATLAB function.

• The function that you provide on the command line to codegen or fiaccel.

For example, the following code generates compilation errors:

%#codegen
function varargout = inch_2_cm(varargin)
for i = 1:length(varargin)
   varargout{i} = varargin{i} * 2.54;
end

To fix the problem, write a top-level function that specifies a fixed number of inputs and outputs. Then call inch_2_cm as an external function or local function, as in this example:

%#codegen
function [cmL, cmW, cmH] = conv_2_metric(inL, inW, inH)
[cmL, cmW, cmH] = inch_2_cm(inL, inW, inH);

function varargout = inch_2_cm(varargin)
for i = 1:length(varargin)
   varargout{i} = varargin{i} * 2.54;
end

For code generation, you can use curly braces {}, but not parentheses (), to index into varargin and varargout arrays. For more information, see Supported Index Expressions.

If you use an expression to index into varargin or varargout, make sure that the value of the expression can be computed at compile time. For examples, see Apply Operations to a Variable Number of Arguments.

Generated code treats varargin as a read-only variable. If you want to write to input arguments, copy the values into a local variable.