Matlab Coder, set the size of a formal parameters array as indicated by another formal parameter

I want to create a c version of the function 'foo' from Matlab with the Matlab coder. The function is called in matlab by the following main script:

N=7;
temp=ones(N,1);
res=foo(N,temp)

By using the Matlab coder, it sets the dimension of temp to 7 in the c code.

How do I tell the Matlab coder that the variable 'temp' in c must have dimension N?

Answer 1

[Harsh]

Hi @V Latorre,

The dimension of “temp” in your code is fixed as “N” is statically defined to be 7. Therefore, when the C code is generated using MATLAB coder it optimizes the code and generates code for a fixed size array. To explicitly define variable-size data, use the function “coder.varsize” and you can take N as an input in your main script. Below is an example code snippet to achieve this –

function res = callFoo(N) 
    %#codegen 
     temp=ones(N,1); 
     coder.varsize('temp', [10 1], [1 0]); % only the first dimension is variable with upper bound of 10 
     res=foo(N,temp); 
end

To learn more about code generation for variable sized arrays please refer to the following documentation - https://www.mathworks.com/help/simulink/ug/what-is-variable-size-data.html