Running Simulink from within a Matlab function

I was running Simulink from the main script with FastRestart and avoiding the use of simset and all was good.

However, after enclosing the script in a function so that I can call it from a different script for different input data, I now get an error related to the workspace. Basically, Simulink is no longer able to access the workspace within the function.

I have found solutions on-line using simset, but this is not an option in my case. Assuming sfile is my Simulink file, I first load the system

load_system(sfile);

and then set-up the FastRestart settings

set_param(sfile,'FastRestart','on');
set_param(sfile,'SaveFinalState','on');
set_param(sfile,'SaveCompleteFinalSimState','on');
set_param(sfile,'SimulationCommand','update');

Now, the error occurs on this last line, i.e. when I am updating the Simulink file. Basically, Simulink returns an error because it does not recognize mdl.tStep, i.e. the step size length, as a structure because it is not specified. In fact, it is because it is in the workspace.

So, my question is how I can sort out this problem. Is it possible to use set_param to change the workspace now that simset is deprecated? Or should I rather set all variables through set_param individually?

Answer 1

[Brandon Eidson]

Hey Enrico, the reason you are getting an error now that you have enclosed the script in a function is because a function has its own workspace separate from the base workspace. You can read more about this distinction in the documentation linked to below.

https://www.mathworks.com/help/matlab/matlab_prog/base-and-function-workspaces.html

Because you call the model from the function, the model only has access to the function workspace. If the simulation depends on any user-defined variables, such as your "tStep", and you want to update or simulation the model from a function, you will need to pass those user-defined variables to the function as arguments.

[Enrico Anderlini]

Thanks Brandon. You are absolutely right. I sorted out the problem by assigning all variables with the assignin command. Not a very neat solution, but effective nonetheless.