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[Panagiotis Foteinos <>]

Yes, it is an exact predicate, inexact construction kernel. 

This is exactly what I am thinking... I am running out of precision. The exact construction kernel, however, is not an option for my code. :(

Thank you,
Panagiotis

On Fri, Aug 28, 2009 at 5:49 PM, Ben Supnik <> wrote:

The experts will correct me I am sure, but ...

This is an exact predicate, inexact construction kernel.

If I understand correctly, this kernel can tell you IF the triangle is degenerate, but if it is not degenerate it might still NOT be able to calculate the area properly, since the underlying numeric type (double) can round out.

Try using CGAL::Quotient<CGAL::MP_Float> instead of double...if things get better maybe it's a construction issue?

cheers
ben

Panagiotis Foteinos wrote:

I am using the  CGAL::Filtered_kernel<CGAL::Cartesian<double> > kernel.

On Fri, Aug 28, 2009 at 5:27 PM, Ben Supnik < <mailto:>> wrote:

   What Kernel are you using?


   Panagiotis Foteinos wrote:

       Hello everybody.

       I observed something strange.

       If a triangle t(p, q, r) is close to a degenerate one with the
       value, however, of the predicate t.is_degenerate() always being
       FALSE, then during the calculation of CGAL::squared_radius(p, q,
       r), the assertion:

       ********************************************************************************************
         terminate called after throwing an instance of
       'CGAL::Assertion_exception'
        what():  CGAL ERROR: assertion violation!
       Expr: ! CGAL_NTS is_zero(den)
       File:
       /scratch/local/CGAL-3.4/include/CGAL/constructions/kernel_ftC2.h
       Line: 60
       ********************************************************************************************

       is trigerred, and the calculation fails.

       Unfortunately, this error is difficult to be reproduced, but
       sometimes it happens.


       Is this behavior expected? Is it relevant to the fact that the
       triangle is almost degenerate?


       Thank you,
       Panagiotis


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