I think you might have said this in your answer, but I didn’t quite grasp it. The solution is: Use an action (or condition) instead of an expression & copy the results back to any amount of variables.
- Setup an action (or condition) with the arguments/parameters (of any type), that you need for your calculation and the parameters of type variable where you want to output/return your results in.
Create your function logic using the input variable:
3.
Use the function in events:
4.
It works:
This was only an example, it works for my case perfectly. I even return the variables back to where they came from, since my q;r input should become an q;r output (from fractional to whole numbers).
My application:
most important to me. It looks clean, minimal and pretty 
In events:
