This demo displays the several example functions of closed curves.
A closed curve is a curve such that X(t0_min)=X(t0_max). To change which funtion is viewed,
type the function title into the definition of X(t). For example, X(t)=ellipse(t).
Change the value of t0 and other variables as in earlier demos.
As in earlier demos, there are "Show entire curve" and "Show Color Spectrum" options.