damped pendulum

vel -= 9.8*Math.sin(theta)*dt*exp(-b*dt);

Where b is some positive number.

[Edited by - erissian on January 22, 2006 9:37:31 AM]

hm...I can change the general speed of the pendulum using that but I'm looking for dampening where the pendulum will slow down and eventually stop

Whoops, I misread that.
vel -= 9.8*Math.sin(theta)*dt;
vel *= exp(-b*dt);
theta += vel*dt/RADIUS;

That's a traditional dampening factor for oscillations.
As you keep calling this function, that exp(-b*dt) term will keep multiplying itself. After n iterations, the factor becomes exp(-b*dt*n). As n increases to infinity, -b*dt*n approaches negative infinity, and that means exp(-b*dt*n) approaches 0.

So calling vel *= exp(-b*dt) repeatedly reduces the velocity to 0 over time. You control how fast by increasing b.

Thanks, it works perfectly! :D