[ODE] ODE spatial inconsistency

Jon Watte (ODE) hplus-ode at mindcontrol.org
Thu Jun 21 14:53:03 MST 2007



Marcin Pilat wrote:

> I guess I failed to state that in my mails - I am running the 
> deterministic version of ODE (using dWorldStep) and when I run the 
> sample at the same x,y position, the result is identical every run.  
> However, the problem arises when I vary that x,y position.

Yes, that's to be expected. No numerical simulation will be bit 
deterministic when moving the reference frame around. If you want some 
simulation where that is true, your only option would be to create 
something that uses fixed point with very large number representations 
(64 bits might not be enough, depending on how far you'll want to move it).

For more information on numerical computing, see the following paper:
http://docs.sun.com/source/806-3568/ncg_goldberg.html

Cheers,

			/ h+


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