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<TITLE>Crystal Space: csPhyziks ODE Solvers</TITLE>
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<H3> 6.7.8 ODE Solvers </H3>
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<P>
An ODE is an <EM>Ordinary Differential Equation</EM> solver. `<SAMP>ctWorld</SAMP>'
starts out with a default ODE solver of Runga-Kutta order 4. This is a
fairly good one for stability and has only a moderate performance hit.
</P><P>
If you notice your objects freaking out and disappearing (usually by flying
off into space), you probably have a stability problem. Springs with high
constants (stiff) are a classic for stability problems.
</P><P>
If you need either more speed or more stability, you may want to use a
different one. Improved stability means decreased performance and vice versa.
Basically improved stability is gained by more complete evaluations of the
whole system per time step (call to evolve).
</P><P>
The problem is that the slower your frame-rate is, the bigger time steps the
dynamics solver will be solving for. Big time steps contribute to instability
as well. So you can try to fix instability by using a more sophisticated
ODE solver like Runga-Kutta with adaptive step sizing (not yet
implemented), but the resulting performance hit could cause more instability.
So it can be a no-win situation when choosing and ODE solver if you have
a very low frame-rate. Then it's time to up the system requirements of your
application.
</P><P>
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