CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Panagiotis Foteinos wrote:
> Hello.
>
> I am using the Delaunay_d class for the triangulation of 4D points. I am 
> also using the Cartesian_d<double> kernel.

Looking at the documentation here:

http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Kernel_d_ref/Class_Cartesian_d.html#Index_anchor_736

you'll see that you need to use an exact number type such as CGAL::Gmpq 
(in particular with collinear points) to compute safely the triangulation.

S.

> I observed that the insertion of the following simple point sequence:
>
>     1st point:  6.8,    6.8,    6.8,    6.8
>     2nd point: 6.8,    6.8,    6.8,   43.2
>     3rd point:  6.8,    6.8,   43.2,   6.8
>     4th point:  6.8,    6.8,   43.2,  43.2
>
> triggers, during the insertion of the 4th point,  the following assertion:
>
>     terminate called after throwing an instance of 
> 'CGAL::Assertion_exception'
>     what():  CGAL ERROR: assertion violation!
>     Expr: j != dim
>     File: .../CGAL-3.6.1/include/CGAL/Kernel_d/HyperplaneCd.h
>     Line: 103
>     Explanation: HyperplaneCd::constructor: cannot use o to determine side.
>
>
>
> Is there a workaround? Why is this behaviour happening?
>
>
> Thank you,
> Panagiotis Foteinos