[ Thanks to Doug Loss
for this link. ]
“Mek is mechanics simulation software. You input some
particles, give their initial positions, velocities, masses,
electric charges. You specify external fields. Trajectories are
computed in real time, you can zoom in and out, speed up or slow
down the simulation. Force and velocity vectors can be output
to be used inside a spreadsheet or gnuplot….”
“Lum is a simulator for centered optic systems. You put optical
devices on an axis, then you can request drawing of distinguished
light beams to find the image of an object. You can bind a bitmap
image to an object, and see its projection on the screen….”
“geg is capable of drawing 2-dimensional mathematical functions
within a nice user interface. e.g., f(x) = 3 + sin(x/2). geg allows
you to view multiple functions simultaneously, with each function
drawn in a different color. Functions can be selectively erased and
are easily identifiable by colour matching. The viewport can be
zoomed in and out, and can zoom in on selected regions.”