...Simulation with Lagrangian method, both symbolic, and by numerical derivation. All well-grouped in folders. there is also a 'review' in 3 demos of the Newtonian dynamics: mass-spring systems. most of progs are written in C, with use of SDL lib to display simple graphics and have real-time interactivity. As to programming complexity, it's very simple... this all aims at classical physics simulation in a simple but efficient way. The numeric stuff really just illustrate the use of a real little physics-engine aimed at articulated body simulation... that's the funnest part of it: but of course much more is coming. ...