Help needed to plot parametric curves

["Nathaniel J. Schwartz" <schwartznj@vcu.edu>]

I am new to programming, math and of course ePiX, but I'd like to plot 
the cycloid curve for a paper I'm doing.

However, I can't figure out how to set up the function. I may be way off 
track here, but I made a function that returns points like so:

P cycloid(double a, double t)
{
    double x = a*(t - Sin(t));
    double y = a*(1 - Cos(t));
    P xy = (x, y);
    return xy;
}

I am not even sure if you can plot a function that returns P, and I'm 
not sure how to use the "plot" command to get it to plot a function like 
this. Since there are no explicit examples in the documentation and 
since I'm very inexperienced, I could really use some pointers here.

I wonder if you could provide some hints as to a good way to tackle this 
problem, or direct me to more information for beginners.

Thank you very much!