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From "Maciej Szefler" <...@intalio.com>
Subject Re: ODE sensitivity to displacement in space or time
Date Thu, 04 Jan 2007 18:42:46 GMT
I believe you intended to post this message to the Maven user's
mailing list. The phenomemon you are observing is consistent with MUP
(the maven uncertainty principle) which states that two executions in
different locations or at different times will produce different
results almost surely. There is a conjecture that states that this
principle applies to anything built with maven and anything that
references or is referenced by anything  built with maven (directly
/or/ through transitive dependencies) . While the conjecture is
generally believed to be true no proof is known at this time.
-mbs



On 1/4/07, chris <dragonmagi@gmail.com> wrote:
> Hi,
>
> For my Thesis, I had reason to perform a number of identical
> experiments with simple variations: displacements in space or time.
> One set of experiments was using ODE:
>
> I did a simple rigid body physics experiment using pyode: dropped a
> box near a stationary box onto a plane. I saved an image of the rest
> position of the box. The experiment is repeatable: the box lands in
> same place each time relative to the stationary one.
>
> Then I moved the whole experiment by (10,10,10) and repeated it. The
> box rest position was different.
>
> I also repeated the first experiment with the only difference being
> that I programmed it to wait 8000 seconds before dropping the box.
> Again the rest position was difference.
>
> What do the developers of ODE have to say as to the cause of the
> sensitivity of ODE to changes in position or time?
>
> Attached are images of the rest position in the first and second
> experiments and the code used to produce each. Also image of the time
> displaced version and its code.
>
> The hardware I was using was a VAIO notebook: intel 770 CPU with
> radeon x600 GPU. For python install I followed the steps from Miriam
> English:
>
> 1. installed python 2.4
>        python-2.4.3.msi
>        http://www.python.org/ftp/python/2.4.3/
>
> 2. edited autoexec.bat to add:
>        SET PATH=%PATH%;C:\python
>        SET PYTHON=C:\PYTHON\
>
> 3. installed pyOpenGL
>        PyOpenGL-2.0.2.01.py2.4-numpy23.exe
>        http://pyopengl.sourceforge.net
>
> 4. Copied glut32.dll to the C:\python\Lib\site-packages\OpenGL
> directory. (This is a *crucial* step.)
>        glut32.dll
>        http://www.xmission.com/%7Enate/glut.html
>
> 5. installed OpenGLContext
>        OpenGLContext-2.0.0c1.win32-py2.4.exe
>        http://pyopengl.sourceforge.net/context/
>        (downloaded from http://pyopengl.sourceforge.net/ )
>
> 6. installed PIL (python Image Library)
>        PIL-1.1.5.win32-py2.4.exe
>        http://www.pythonware.com/products/pil/
>
> 7. installed pyODE
>        PyODE-1.1.0.win32-py2.4.exe
>        http://pyode.sourceforge.net/
>
>
> Now I can double-click on the tutorial3.py from
> http://pyode.sourceforge.net/ and it simply runs!
>
>
> thanks,
>
> chris
>
>
>

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