[ODE] numerical stability (sort of)

[Shaul Kedem]

Hi,
 Make two versions of the boxstack code (for example)
: the first one saving the key presses(as they are
being dropped) and the time, and a second version
which loads the saved information (once, at the
beginning) into memory (*not* swap) and replays the
key presses at the specific time.

 You should get (almost) exactly the same behaviour...

Shaul

--- tbp <ode at ompf.org> wrote:
> I've been toying with ODE for a while and at some
> point got bored enough 
> to profile it and fancy the idea of cutting some
> corners.
> I thought about measuring the time it takes some
> system (like various 
> piles of boxes on an inclined ground) to converge
> (everything coming to 
> rest and being auto disabled).
> 
> It wasn't a good idea, but my first surprise was
> that contrary to gcc 
> 3.4 built dll, msvc 7.1 ones (my own builds) don't
> even allow 
> reproduceable runs within the same session (that is
> destroying box 
> bodies+geoms and simulating again gives different
> result). A cold run 
> gives reproduceable results. Really weird.
> As http://ode.org/snapshots/bin/ proved empty (i
> guess it's still on the 
> move), i cannot check against a semi official bin.
> So my first question is: is there anyone kind enough
> to provide me with 
> a recent snapshot msvc built dll (single precision,
> no need for opcode)?
> 
> Then, i wonder what kind of system would allow me to
> have reproduceable 
> behaviour between compilers & compile options (while
> still being large 
> enough to benchmark in a useful way). Obviously
> stacks of boxes that 
> collapse hitting each other isn't what i'm looking
> for :)
> Maybe tons of semi isolated couple of geoms? Any
> idea?
> 
> 
> Regards,
> 	tbp.
> 
> 
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