Double Pendulum Simulation vs Federgraph

In mathematics, in the area of dynamical systems, a double pendulum is a pendulum with another pendulum attached to its end, and is a simple physical system that exhibits rich dynamic behavior. The motion of a double pendulum is governed by a set of coupled ordinary differential equations. For certain energies its motion is chaotic. This application solves these differential equations using the Runge-Kutta method for the time stepping. You can influence the movement of the pendulum by holding your device in different positions.

Federgraph is a function plotter app to visualize a special built in function z = f(x, y) in 3D. The physical model behind the app is a system of springs. The built in function produces a variety of colorful pictures, some of which appear to have a face. Changing the parameters of the physical model will trigger a recalculation of the image.