Simulink function block array element operation with a fixed size

How can I achieve a array element opertion within the function block? The output of the function is sent to a integrator. Therefore, the output has a defined size.

Answer 1

[Ameer Hamza]

Change the code inside MATLAB function block to this

dy_dt = zeros(5,1);
dy_dt(1:3,:) = vars.g*u.*0.1.*y(1:3,:);
dy_dt(4:5,:) = vars.lambda*u.*0.1.*y(4:5,:);

Note that the first line is necessary for telling the compiler about the size of output dy_dt. Also, you cannot use zeros(var.size,1) since the compiler still cannot decide the value at compile time.

[Jiwei Yao]

Thanks!! But is there any way that I can change the dy_dt size without going into the function block?

[Ameer Hamza]

See the attached files. Note that, inside the MATLAB function block, I have defined a non-tunable parameter with the name of mySize (variable with this name also need to be defined in base workspace). You can check its properties by clicking the "Edit Data" button on the toolbar. This button will only appear when you open the MATLAB function block.

[Jiwei Yao]

Thank you so much!!!

[Ameer Hamza]

I am glad to be of help!