Hit Read to read in initial conditions from the data file, or add particles by clicking in the panel or moving the Number slider. Other initial condition files are in_2, in_3, and in_4 (CIT stands for California Institute of Technology).

The particles move on a two dimensional plane and interact with a 1/rp force (smoothly cut off at about the particle radius) with p set by the Power slider. You can reverse time and change the force from repulsive to attractive using the check boxes. The Force slider changes the strength of the interaction. Clicking on the panel adds a particle at that point. The velocity of the new particle is from a random distribution with width set by the Velocity slider if Random is selected, or with give vx and vy if Fixed is selected. The number of particles can also be changed using the Particles slider, when the velocities are chosen from the random distribution.


I am not yet sure how accurate my integrator is, so energy conservation and reversibility might not be very faithful. Larger values on the Accuracy slider (which increases the number of subintervals between plotted values for the integration) and smaller values of Speed (which changes the time interval between plots) should be better. If anyone is interested in trying to implement a more faithful symplectic integrator in the java program, please contact me.

Last modified: March 15, 2006, Michael Cross