MATLAB function block error in Simulink

Hi,

I am trying to run a function in Simulink model. I have the function working without any error if I call it in an m-script. However, if I add the same function in MATLAB function block, I have dimension errors.

Why don't I see these errors when I call it in m-script? Is there is a way to debug this?

Thanks

Answer 1

[Abdolkarim Mohammadi]

Unlike m-file functions, MATLAB function block does not apply automatic array expansion. The simplest way to overcome is to define your m-file function as an extrinsic function in the MATLAB function block.

function v = fcn (u) % MATLAB function block 
coder.extrinsic ('MATLAB function name'); % m-file function 

https://www.mathworks.com/help/simulink/ug/calling-matlab-functions.html

[Rubeena Parveez]

Hi Abdolkarim Mohammadi-Bilani,

Thanks for your response.

This solution somewhat worked but I am trying to call to functions inside matlab function block as shown below.

I have all undefined variables error. p, q, r, u, v are available in workspace. a, b, c, x, y, z, a1, b1, c1, m, n are defined in initABC and runABC.

Am I missing something here?

function [a, b, c] = fnc() %Matlab function block
 a = 0; b = 0; c = 0;
 coder.extrinsic ('initABC');
 
 [a, b, c, x, y, z] = initABC(p, q, r); %m-file function
 coder.extrinsic ('runABC');
 for i= 0:20
      [a1, b1, c1, m, n] = runABC(u, v, x, y);%m-file function
      
 end
 
 a = a1;
 b = b1;
 c = c1;
end

[Abdolkarim Mohammadi]

You should include the coder.extrinsic command before all other commands. In addition, I think it is better to do all of the calculations of the initialization and the main loop in a single m-file.

function v = fcn (u) % MATLAB function block 
coder.extrinsic ('initAndRunABC'); % m-file function
v = 0; % pre-initialization
v = initAndRunABC (u); 

[Rubeena Parveez]

How do I access base workspace variables in MATLAB function block?

[Abdolkarim Mohammadi]

Create a Constant block and enter that variable's name in the Value field. Connect the Constant block to the input of the function block. If you need multiple inputs, you first define them in the function header. Then the appropriate input ports will appear on the block.

function v = fcn (u1, u2, u3) % MATLAB function block 

[Rubeena Parveez]

Thank you, this works but I read that coder.extrinsic does not support code generation. Is there any other way to do this?

[Abdolkarim Mohammadi]

As far as I know, there is no way. As emphasized by documentation and the top contributor of this forum.