How can i add an equation to a block (impedance measurement)?

I have a simple RLC circuit. I added an impedance measument block to measure its impedance. But I need to add length, area etc. parameters to my system. I have an equation for this. How can I integrate this equation? So, I need to add this equation and with the R value resulting from this equation, the circuit should work and the impedance measument should measure the impedance.

I tried turning the circuit into a subsystem and adding user-defined functions, but I don't know which one I should use. many won't let me add an equation like this.

Answer 1

[Joel Van Sickel]

You have 2 options. If it is a static value of impedance, you can pre calculate your circuit parameters such as R = R_pu*Length and put R into the resistance parameter. Or, if you need impedance to change dynamically, you can use the variable resistor and implement that equation specifically in simulink and pass it to the resistor. The same is possible for inductors and capacitors to create any impedance value that you want.

https://www.mathworks.com/help/simscape/ref/variableresistor.html

It might help to take the basic free training here: https://matlabacademy.mathworks.com/details/circuit-simulation-onramp/circuits