CGAL users discussion list

[Ben Haller <>]

On Jul 19, 2010, at 4:06 PM, Ben Haller wrote:

>  Hi!  I'm very new to CGAL, so please forgive any cluelessness.  I'm on Mac 
> OS
> X 10.6.3 using CGAL version 5.0.0 I think (my /opt/local/lib/libCGAL.dylib
> points to libCGAL.5.0.0.dylib), installed using MacPorts.  I'm trying to use
> the Delaunay_d class to do Delaunay triangulations.  I'm wrapping the calls 
> in
> R and am calling them through R's .C() calling interface.  I don't think 
> that's
> particularly relevant to my problem, though, so let's not get too lost in 
> the
> details.  Test runs that I did with this wrapping worked fine, but now that 
> I'm
> trying to use the code with my actual dataset, the problem is that I'm 
> getting
> an assertion from function_objectsCd.h:285 when I insert a particular point
> into the data structure; the assert is "Contained_in_simplex_d: A not 
> affinely
> independent."  I have no idea what that means, or how to fix it...

  I have just discovered that adding a small amount of random noise to the 
points I am inserting prevents the assertion.  This was based on the 
intuition that the problem might be related to some sort of symmetry in the 
points inserted.  The random noise seems to break the symmetry, and the 
assertion is no longer triggered.  I'm not happy with this solution, though, 
as it seems both to be 1) a hack, and 2) probably unreliable.  Does anybody 
have a better suggestion?  Is there a really good reason why CGAL needs to 
assert on this condition in the first place?
  Thanks!

Ben Haller
McGill University