Variable gets cleared after each simulation step with simulink

Hello all,

I am using a System Object (SO) in combination with Simulink to simulate some stuff. Within that SO multiple objects of normal Matlab classes are instantiated in the setupImpl method. From one stepImpl to the next it seems that Matlab/Simulink clears/re-initializes the properties of those Matlab objects which in return costs time. How can I prevent this from happening? I want the memory of the Matlab Objects to be untouched because the size of their properties is large and don't change over time. I thought of using persistent variables but I fail in defining persistent properties. Is that possible and if so, how?

Any hint is highly appreciated!

[Stefan]

Dear Friedrich,

thanks for your request - we will be in touch shortly.

Thanks and best,

Stefan

Answer 1

[Malay Agarwal]

Hi @Friedrich,

According to the documentation of the setupImpl method, you need to define properties as private properties to avoid them from being recalculated on each call to stepImpl (https://www.mathworks.com/help/releases/R2021b/matlab/ref/matlab.system.setupimpl.html#:~:text=class%20definition%20file.-,Use%20setupImpl,-to%20set%20private)

"Use setupImpl to set private properties so they do not need to be calculated each time stepImpl method is called."

Please make sure that all your instances are defined as private properties your code.

Refer to the following resource for more information on how to use the setupImpl method: https://www.mathworks.com/help/releases/R2021b/matlab/ref/matlab.system.setupimpl.html

Hope this helps!

[Friedrich]

Hi @Malay Agarwal,

thanks for your hint. I looked into my code and the properties that I mentioned in my previous post were already set to private ... so, the problem remains.

Meanwhile, I shifted all these properties into one new handle class. I can see now, that Simulink doesn't clear the values from one step to another. Nevertheless, it seems that some copying (or whatever) is going on, since the simulation time is far too long... Could that be? And if so, how do I change this behaviour?

I just need a piece of memory that I can overwrite over and over again ... no reallocation, no reinitalisation, no copying or whatsoever.

[Friedrich]

I'll try to come up with a minimal example as soon as possible. I guess that would help all of us.

[Malay Agarwal]

Yes, I think that would be very helpful!