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Re: [cgal-discuss] how to understand CGAL's computational accuracy


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  • From: Aomandeyi <>
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  • Subject: Re: [cgal-discuss] how to understand CGAL's computational accuracy
  • Date: Fri, 12 Mar 2021 07:34:49 -0600 (CST)
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Aha! i can give you counter-example:
------------------------------
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <sstream>
typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;
typedef Kernel::Point_2 Point_2;
int main()
{
Point_2 p(0, 0.4), q(1, 0.7), r(2, 1);
{
std::cout << std::setprecision(17) << p << " " << q << " " <<
r << "\n";
std::cout << (CGAL::collinear(p, q, r) ? "collinear\n" : "not
collinear\n");
}

{
q = CGAL::midpoint(p, r);
std::cout << std::setprecision(17) << p << " " << q << " " <<
r << "\n";
std::cout << (CGAL::collinear(p, q, r) ? "collinear\n" : "not
collinear\n");
}


return 0;
}
--------------------
the results:the same input but different output
----------------------------------------
0 0.40000000000000002 1 0.69999999999999996 2 1
not collinear
0 0.40000000000000002 1 0.69999999999999996 2 1
collinear
---------------------------------------------



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Sent from: http://cgal-discuss.949826.n4.nabble.com/



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