CGAL users discussion list

["jim.wilenius" <>]

Using the following kernel (exact predicates, exact constructions)

typedef CGAL::Lazy_exact_nt<CGAL::Gmpq> NT;
typedef CGAL::Filtered_kernel<CGAL::Simple_cartesian<NT> > Kernel; 

and the following two polygons:  (attached) 
http://www.nabble.com/file/p26073101/minkowskiError.dat minkowskiError.dat 

8
-17.12124659567309237218069029040634632110595703125
-19.74096318533549521134773385711014270782470703125
7.61619682762335958869925889302976429462432861328125
54.47136708455386866489789099432528018951416015625
-22.36067977499789094508741982281208038330078125
114.4251202897963821669691242277622222900390625
36.8257762059193964887526817619800567626953125
84.831892299337738450049073435366153717041015625
90.77279900751187824425869621336460113525390625
111.8054037001339793278020806610584259033203125
66.03535558421543782969820313155651092529296875
37.5930734302446154515564558096230030059814453125
96.01223218683668392259278334677219390869140625
-22.36067977499789094508741982281208038330078125
36.8257762059193964887526817619800567626953125
7.23254821546075010729737186920829117298126220703125
6
-0 -20.847474035333203090658571454696357250213623046875 
-0 -80.750575916330689096866990439593791961669921875 
-41.6949480706663990758897853083908557891845703125
-101.598049951663909951093955896794795989990234375
-83.389896141332798151779570616781711578369140625
-80.7505759163307033077217056415975093841552734375
-83.389896141332798151779570616781711578369140625
-20.84747403533319953794489265419542789459228515625
-41.6949480706663990758897853083908557891845703125 -0

I get this exception when calling  minkowski_sum_2(..) :

terminate called after throwing an instance of
'CGAL::Precondition_exception'
  what():  CGAL ERROR: precondition violation!
Expr: Segment_assertions::_assert_is_point_on (p, cv1, Has_exact_division())
&& Segment_assertions::_assert_is_point_on (p, cv2, Has_exact_division())
File: /usr/local/include/CGAL/Arr_segment_traits_2.h
Line: 598

But using the following kernel works:

typedef CGAL::Lazy_exact_nt<CGAL::Quotient<CGAL::MP_Float> > NT;
typedef CGAL::Filtered_kernel<CGAL::Simple_cartesian<NT> > Kernel; 


Why does the first kernel give me an exception?  None of the kernels should
produce exceptions in this case right?
This is really really troublesome.

-- 
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