CGAL users discussion list

[Andreas Meyer <>]

Which Kernel did you use? Cartesian<double> does not use exact computation. 
If 
you need exact predicates and/or constructions, see 

http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Kernel_23_ref/Chapter_intro.html#Section_2.9

A nice paper about robustness (problems of non-robustness) can be found at

http://www.mpi-inf.mpg.de/~kettner/pub/nonrobust_esa_04_a.html

Best Regards,
Andreas Meyer

On Thursday 12 April 2007 10:13, Matthieu Chavent wrote:
> I resolved my problem with compiling with -DCGAL_CH_NO_POSTCONDITIONS
> and now it's work well but I would like to know how this problem appears 
> and if I disable this option it possible to have concave objects?
>
> Thank you in advance!
>
> Matthieu Chavent a écrit :
> > Hello cgal users!
> >
> > I performed a convex hull of a set a 3D points. I know that the set of
> > points define a convex volume. I use the function CGAL::convex_hull_3
> > on my points list. I  obtain a Polyhedron_3 in almost cases but one
> > time a have the error message:
> >
> > CGAL error: postcondition violation!
> > Expr: is_strongly_convex_3(P, traits)
> > File: /home/Chavent_Matthieu/CGAL-3.2.1/include/CGAL/convex_hull_3.h
> > Line: 468
> > Aborted (core dumped)
> >
> > It is very strange because I know that the sets of points that form
> > the Polyhedron define a convex volume: So, I would like to know if
> > somebody had the same problem and How can I get through this error.
> >
> > Thank you in advance!
>
> ---------------------------
>
> Matthieu Chavent
> LORIA
> PhD student
> 
> tel: ++33(0)3-54-95-86-05
>
> ---------------------------