If I give you a function f(x) (cartesian) and I ask you to rotate it about the x axis (counterclockwise) by an angle phi, what is the new function formula? I remember I did this with matrices, but I can't remember the one for functions. For convenience, let angle phi be 0, pi/2, 3pi/2, and 2pi. I am guessing 0 would remain the same. I just don't know how to use matrices on functions. Does anyone understand my question?