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[Myirci <>]

Thank you sebastien,

it solved my conversion problem !

On Thu, Feb 14, 2013 at 4:55 PM, Sebastien Loriot (GeometryFactory) <> wrote:

You can try that:

Gt::RT r = 0.75;

Rational rr( CGAL::exact(r).mpq() );

Sebastien

On 02/14/2013 11:50 AM, Myirci wrote:

Bonjour,

I'm using segment delaunay graphs and conics arrangements. At some point
of my program I need to convert Ring Type variables to Rational
variables to create the conic arcs. My original code is very long, but I
generated the same condition in the program below. How can I do the
conversion? For just one simple parabola I can supply the Rational
coefficients by hand but in my original program, the numbers are not so
simple and the coefficients are calculated in run time.

Bonne journée
Merci beaucoup

#include<iostream>

#include  <CGAL/Exact_predicates_exact_constructions_kernel.h>

#include  <CGAL/Segment_Delaunay_graph_2.h>

#include  <CGAL/Segment_Delaunay_graph_traits_2.h>



typedef  CGAL::Exact_predicates_exact_constructions_kernel                           Kernel;

typedef  CGAL::Segment_Delaunay_graph_traits_without_intersections_2<

         Kernel,


         CGAL::Integral_domain_without_division_tag>                                           Gt;

typedef  Gt::Point_2                                                                                              Point_2;

typedef  CGAL::Segment_Delaunay_graph_2<Gt>                                              SDG_2;



#include  <CGAL/basic.h>


#include  <CGAL/Cartesian.h>


#include  <CGAL/CORE_algebraic_number_traits.h>

#include  <CGAL/Arrangement_2.h>

#include  <CGAL/Arr_conic_traits_2.h>



typedef  CGAL::CORE_algebraic_number_traits                                                  Nt_traits;

typedef  Nt_traits::Rational                                                                                    Rational;

typedef  Nt_traits::Algebraic                                                                                  Algebraic;

typedef  CGAL::Cartesian<Rational>                                                                    Rat_kernel;

typedef  CGAL::Cartesian<Algebraic>                                                                  Alg_kernel;

typedef  CGAL::Arr_conic_traits_2<Rat_kernel,  Alg_kernel,  Nt_traits>                Traits_2;

typedef  Traits_2::Curve_2                                                                                   Conic_arc_2;

typedef  CGAL::Arrangement_2<Traits_2>                                                           Arrangement_2;



int  main(void)  {

     //  Parabola:  y  =  -3/4x²

     Gt::RT  r  =  0.75;

     Gt::RT  s  =  0;

     Gt::RT  t  =  0;

     Gt::RT  u  =  0;

     Gt::RT  v  =  1;

     Gt::RT  w  =  0;

     Point_2  ps  =  Point_2(2,  -3);

     Point_2  pt  =  Point_2(-1,  0.75);



     //  Does  not  compile:  RT  number  type  must  be  converted  to  Rational!  How?

     Conic_arc_2  arc(r,s,t,u,v,w,  CGAL::COUNTERCLOCKWISE,  ps,  pt);

     if(!arc.is_valid())  {  std::cout  <<  "NOT  VALID"  <<  std::endl;  }

     return  0;

}


--
Murat Yirci

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Murat Yirci