scott wrote:
> The only difference is that in the evaluate function without the 
> supplied derivative, you don't need to update the state, simply return 
> the derivative at time t using the initial state.
> 
>>       b = evaluate (v,p) t (dt/2) a
>>       c = evaluate (v,p) t (dt/2) b
>>       d = evaluate (v,p) t dt     c
>>       dv = (fst a + 2 * (fst b + fst c) + fst d) / 6
>>       dp = (snd a + 2 * (snd b + snd c) + snd d) / 6
>>     in (v + dt*dv, p + dt*dp)

...

> 5) Take a weighted average of all the derivatives you just caluclated, 
> a-d, this gives the most accurate derivative.
> 
> 6) Use this weighted average to actually advance your state by dt using 
> normal Euler integration.

Here's a question: The derivative is based on the forces applied to the 
current particle.  The only way these forces change is when a particle 
collides with other particles (or ceases to collide).

So, for each of the above, am I to run a full collision detection?

-- 
...Ben Chambers
www.pacificwebguy.com

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