vect provides a 3D Vector type. newton has some utilities for
performing Molecular Dynamics.
cmd/shm is a program that produces a comparison between the analytic
solution of a simple harmonic oscillator and simulations using the Euler
and Stoermer-Verlet algorithm.
cmd/square simulates a finite rectangle cut out of a square grid of
particles connected with springs. The central particles (one, two or
four, depending on the rectangle dimensions) are pulled with a certain
vertical force.