I have two questions about the ModelingToolkit package:
is there a function that determines the list of variables that occur in an expression?
Example: x^2 + y - exp(y) contains x and y
is there a function that simplifies an expression? After writing a linear combination of expressions in my code, a “1x - 0y” pops up, and I would like the second term to be simplified (otherwise, the result of my first question may be irrelevant )