Geometric shapes in the DataGraph Physlet can now be data listeners.
The above examples solves the differential equations for theta and omega for a pendulum and passes
these values to two data graphs for display. A data connection is used to
convert the theta value from the ODE to x and y values. This generates the pendulum
motion in the left hand display. Two other data connections are
used to plot the theta and omega values in the right hand display.