[ODE] ODE spatial inconsistency

Marcin Pilat pilat at cpsc.ucalgary.ca
Wed Jun 20 14:38:15 MST 2007


Actually, that's what I thought at first, but after doing some tests,  
it doesn't seem like it is floating point problems (unless they are  
horribly implemented inside ode).  I posted some data in reply but  
the message was too big and it is still awaiting approval.  You can  
see the graphs from a run of the code above with changing x from  
-100.0 to 100.0:  http://galapagos.cpsc.ucalgary.ca/~marcin/ 
odetestx.jpg (for x), http://galapagos.cpsc.ucalgary.ca/~marcin/ 
odetesty.jpg (for y), http://galapagos.cpsc.ucalgary.ca/~marcin/ 
odetestz.jpg (for z).  If these changes are due to floating point  
problems then why aren't they consistent - i.e. why are there  
plateaus in the graphs with the same values?  It doesn't sound right  
to me.  Any idea of what the problem and/or solution to this would be  
(independent simulations or running everything at the same coordinate  
works for some simple simulations, but in general is not a practical  
option).

Thanks!

Marcin


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