The positive side of the logistic equation is in one and the negative side is in the other. Clicking on the negative side of the graph causes it to zoom in or out depending on which button you press. In any chaos system, iterating the equation produces some great effects. The code is here. Iteration using php.
Iteration involves running a certain equation many times on it's own result.
With certain equations the results will bifurcate, or vary between two values. The code is here . It actually uses four parametric equations to produce a nice effect. The code is here .