Solving ODEs inside a Subsystem in Simulink

Question

I'm trying to figure out how to solve a system of ODEs inside a subsystem in a Simulink model. Basically, each call to this subsystem, which happens at each tick of the simulation clock (fixed-step), entails solving the ODEs. So there's like a different "clock" for the subsystem.

I have an M-file that implements the function for the system of ODEs. Currently, I have a MATLAB Function block for that. It needs a lot of parameters that I can get from the base workspace (via evalin and using coder.extrinsic('evalin') at the beginning). But I'm not allowed to define function_handle objects or inner functions to parameterize the function that is used by ode*. I think that if I'm able to solve the ODEs in this block, I'll have solved my problem. But those restrictions are "ruining" it.

I'd appreciate if you have any ideas of how to accomplish this. I welcome different approaches.

Thank you.

EDIT

A simple example is given below. It attempts to solve the van der Pol equation by changing the mu parameter randomly. This is the main idea I have at the moment, which doesn't work because of the problems mentioned above.

This is the main model with the subsystem:

This is the subsystem:

This is the MATLAB Function block implementation (note that there's an error in the @ symbol, since defining function_handle objects isn't allowed):

Answer 1

Just use the MATLAB Function block as a wrapper. Put the bulk of your code into a "standard" MATLAB function (i.e. one callable from MATLAB, not the MATLAB Function block) and call that function (after defining it as coder.extrinsic) from the MATLAB Function block.