Vector input for MATLAB function block

Hello everyone,

I've been struggling with this problem for a while now and it's beginning to drive me mad:

I have a Simulink MATLAB function block that is supposed to perform some calculations with the last 100 values of a signal. Is there a way to dynamically store the last 100 values of said signal and feed it as an input into the MATLAB function block without using 100 inputs and thousands of memory blocks?

Best regards,

Daniel

[Daniel Schmidt]

I think I found a solution for my problem now. Basically, I introduce a second MATLAB function block to create and store the values.

Since I found this question a couple of times online, I uploaded an example for the calculation of a moving average using this method.

The disadvantage of my solution is, that the vector size (or time constant) needs to be defined directly inside the fcn block but that's fine for my purpose.

Of course, I'm always open for other suggestions. Maybe someone has a more elegant solution?!

Answer 1

[Birdman]

Well, although your problem is ok, usage of Memory block always increases the chance for system to fail if the complexity of your system increases. The best way to hold the value of a signal is to use Enabled Subsystem and that is what I did. I also kept your way and made a comparison. My way also works, see if that helps to you. Notice how I used the Pulse Generator. I also changed the solver type to variable-step since I wanted both your way and my way to take the same step size while solving.

[Daniel Schmidt]

Hi Birdman,

thank you for your answer and for the edited model. The enabled Subsystem looks very promising.

There is just one thing I don't understand in your edited model. The input port 1 of your way (labeled MYWAY) is fed by the output port 2 of my way (labeled YOURWAY). So essentially your version with the enabled subsystem uses the output of my version and thus also uses the memory block.

Best regards

Daniel

[Birdman]

It uses the output of the first MATLAB function(labeled YOURWAY) but does not use the output of the Memory block. Please note that.

[Daniel Schmidt]

"It uses the output of the first MATLAB function(labeled YOURWAY) but does not use the output of the Memory block"

And the first MATLAB function uses the output of the memory block as an input, therefore you still use the memory block. ;)

[Birdman]

Ups yes, that is right. I will reedit the model later today.

[Daniel Schmidt]

Thank you so much for your effort :)

[Birdman]

I changed the Memory block with Enabled Subsystem block this time only. Run it and see the results.

[Daniel Schmidt]

Thank you for the new model. Everything works as intended. Btw, with the delay block, your model even works without the enabled subsystem.

I am going to mark my question as solved. Have a nice day and thanks again.