I'm not sure if that will work, I will give an example of the code to see if that helps. Basically, there is a parameter Kn which I set to 1 in the course of finding the solution which gives the force on an object. I have a function which features Kn which is evaluated numerically at various grid points.
Evaluating the function at the grid and solving the system which results you get the total force (or drag) called dragFZ. I then divide the result by -6*pi*VZ*Kn, another equation which depends on Kn. Although I have assumed Kn=1, I somehow need to take that ratio and plot the result against Kn, as Kn varies from 0 to 1. I have tried the following (where I called Kn t):
but the graph does come out as expected.