[ODE] RE: Torque: Bug in 0.025, apparently fixed in CVS
Ruud van Gaal
ruud at marketgraph.nl
Sun Nov 25 04:09:01 MST 2001
> I tried to get the same result with a minimal ODE program. And to my own
> astonishment, I don't get the same results. Instead, I get
> ---
> Initial matrix:
> 0.00 0.00 1.00
> 0.00 1.00 0.00
> -1.00 0.00 0.00
> post-rel Tx=+:
> 0.00 -0.02 1.00
> 0.00 1.00 0.02
> -1.00 0.00 0.00
To follow up on myself, I got a brainwave; the initial matrix is 4x3, but
should only use the 3x3 components ofcourse. Still, I tried modifying R[11] to
1 instead of 0, making it *look* like some homogenous form (although the would
have to be at R[15] then actually). And lo and behold, when R[11] starts out as
1, the result is correct! The plot thickens.
---
post-rel Tx=+:
0.00 0.02 1.00
0.00 1.00 -0.02
-1.00 0.00 0.00
---
So somewhere in a calculation, R[11] is used. Which it shouldn't, I think, as
it is a 4x3 rotational matrix. It may even be used somewhere as a 4x4 matrix by
mistake (which may lead to strange things). Still, in that case you'd expect
some pretty weird numbers once in a while, so I don't think that's the case.
Hope this helps in finding what is going on here.
Ruud
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