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Hi,

I am using CGAL::intersection() with filtered kernel to intersect two mostly 
identical quadrilaterals (coordinates shown below), but it fails. The 
coordinates of quad vertices are the results of numerical computations. Could 
anybody have any suggestions on how to proceed to this problem? 

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typedef CGAL::Simple_cartesian<double> CK;
typedef CGAL::Filtered_kernel_adaptor<CK> K;
typedef K::Point_2 Point_2;
typedef CGAL::Polygon_2<K>      Polygon_2;
typedef CGAL::Polygon_with_holes_2<K>              Polygon_with_holes_2;
typedef std::list<Polygon_with_holes_2>            Pwh_list_2;


int main ()
{
  Polygon_2 P;
  P.push_back (Point_2 (30.124109628844671, 33.217017971670636 ));
  P.push_back (Point_2 (31.191654501424242, 33.160525861106009));
  P.push_back (Point_2 (31.229498486078121, 34.099148600029707));
  P.push_back (Point_2 (30.184409196038519, 34.168799432512159));
 
  Polygon_2 Q; 
  Q.push_back(Point_2 (30, 34));
  Q.push_back(Point_2 (31, 34));
  Q.push_back(Point_2 (31, 35));
  Q.push_back(Point_2 (30, 35));

  CGAL::intersection (P, Q, ...);

}