[MBDyn-users] Initial assembly phase fails if tolerance is too small: Param_Manip(): divide by zero, probably due to singularity in rotation parameters
masarati at aero.polimi.it
Wed Apr 11 18:48:46 CEST 2012
On 04/11/2012 04:07 PM, Resch Reinhard wrote:
> Dear Mr. Masarati,
> I believe that there is a bug somewhere in the initial assembly code.
> If you run the model in the attached file with a initial assembly tolerance of 1e-16 the simulation works fine.
The model assembles correctly with all residual coefficients == 0 and
only one O(1e-17)
> But if you decrease the initial assembly tolerance to 1e-20 the initial assembly procedure diverges.
> Finally I get this error message: Param_Manip(): divide by zero, probably due to singularity in rotation parameters
The error is not specifically meaningful; the reason is that all the
solution elements grew to 1e+<large value> and thus the orientation
parameters result in a division by zero. I believe there is no point in
setting the tolerance to such a small value. Indeed there might be a
bug somewhere in the procedure, but I do not see it as critical. I'd be
willing to fix it if you can help singling it out, though.
Dipartimento di Ingegneria Aerospaziale
Politecnico di Milano
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