[ODE] how to debug and fix NAN values

Hampa hampa at toribash.com
Mon Oct 22 09:16:33 MST 2007

Hi Bram,

It is the dNormalize4 (b->q) in void dxStepBody (dxBody *b, dReal h)  
in util.cpp.

This is called from dInternalStepIsland_x2.

I checked the values when entering the dxStepBody function and  
(depending on scenario) the lvel, avel, facc or tacc values have  
ended up as nan.

With this I think I need to figure out where in  
dInternalStepIsland_x2 the values are introduced.


On 22 Oct 2007, at 11:45 PM, Bram Stolk wrote:

> Run the app in a debugger.
> You wil get a call-stack.
> We would like to know in what part of the code, the normalization  
> was called.
> When I got this error, it was because I had a triangle that had a  
> zero-length edge.
> Thus, two vertices co-incided.
>   Bram
> On 10/22/07, Hampa <hampa at toribash.com> wrote:
> Hi,
> Every now and then my simulation produces NAN values, usually during
> collisions using hi velocity objects.
> In the debug build (lastets 0.9 svn checkout) I get asserts in:
> ODE INTERNAL ERROR 1: assertion "bNormalizationResult" failed in
> _dNormalize4() [../../include/ode/odemath.h]
> What is the recommended way to debug and fix this kind of problems?
> cheers,
> hampa
> _______________________________________________
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> -- 
> Zapp: Captain's log, stardate...er..
> Kif: Ohhh. April 13th.
> Zapp: April 13th. Point 2.

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