[ODE] deterministic simulations

Erwin de Vries erwin at vo.com
Wed Jun 21 01:55:22 MST 2006

To my knowledge ODE is deterministic as is, as long as you fix the randoms 
used in iteration. I've fixed it up for my own usage a while ago, and it 
looks like its working perfectly for the things i've done. (Capturing input 
on a P4, and playing it back on a Athlon worked fine, even in lengthy 

Are there FPU specifics that could mess things up?


----- Original Message ----- 
From: "Hampus" <hampus at sxp.se>
To: "ode-list" <ode at q12.org>
Sent: Wednesday, June 21, 2006 10:23 AM
Subject: [ODE] deterministic simulations

>I know this topic has been up before.
> I got a reply from another mailing list from a warcraft programmer on
> how they solved FPU problems for deterministic simulations.
> >No, I wrote an FPU emulator in C that used the integer unit for all
> its work. It wasn't pretty. But >by god it worked everywhere, even
> PowerPC. I only had to drop to assembly for __cntlzw (as >well as an
> Intel equivalent that used BSR).
> >Warcraft III utilizes this code; when I last checked, about 5% of
> our execution time was >dedicated to FPU-less floating point math.
> Would and FPU emulator be feasable for ODE too?
> Cheers,
> Hampa
> Toribash.com
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