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[Anton Gladky <question248869@xxxxxxxxxxxxxxxxxxxxx>]

Question #248869 on Yade changed:
https://answers.launchpad.net/yade/+question/248869

    Status: Answered => Open

Anton Gladky is still having a problem:
2014-05-19 11:56 GMT+02:00 Bruno Chareyre
<question248869@xxxxxxxxxxxxxxxxxxxxx>:
> Bruno Chareyre proposed the following answer:
> Is there something special hapening to state-ori before step 154675
> (manipulation in the script, some specialized clump functions, etc?),

No, it is just a free fall of clump and it reaches the floor at the step 154675.
Some more info for previous steps:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
b->id: 209; Iter:154673
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A:  0.934319 -0.193747  0.299181
 0.188102  0.980983 0.0478483
-0.302762 0.0115711  0.952996
....
....
state->ori: 0.9834 0.00922239 -0.153026 -0.0970739
state->angVel: 0 0 0


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
b->id: 209; Iter:154674
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A:  0.934319 -0.193747  0.299181
 0.188102  0.980983 0.0478483
-0.302762 0.0115711  0.952996
M:  0.934319 -0.193747  0.299181
 0.188102  0.980983 0.0478483
-0.302762 0.0115711  0.952996
....
....
state->ori: 0.9834 0.00922239 -0.153026 -0.0970739
state->angVel: 0 0 0


> because orientation quaternion seems very badly normalized.
>
> A rotation matrix should be skew-symmetric, here you have:
> A: 0.934319 -0.193747 0.299181
>  0.188102 0.980983 0.0478483
> -0.302762 0.0115711 0.952996
>
> I'm not sure it is related to your problem, but it is very strange. Orientation is normalized at the end of leapfrogAsphericalRotate, so it should be ok at the next step. But again at step 154676 it does not give a good rotation matrix.
> Something happening at each step, before Newton?!

Hmm, no there is nothing especial. I did not change the code either, as I never
worked with clumps. Interesting is that this clump is not the first one in the
simulation.

Anyway thanks a lot for info! That is something already.

Anton

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