CGAL users discussion list

well, you need a license to use LEDA...

I guess the following paper by Christophe Burnikel may help you
Rational points on circles MPI-I-98-1-023
google can find it, then you can download it from there
(I don't know if it was published)

Best,
        Monique Teillaud


 wrote:
> I need a way to find a rational point on a circle,
> which is as close as possible to a given circular point 
> on this circle. A rational point is a point with rational
> coordinates, the circle itself is rational as well (has
> a rational center, and is constructed of three rational points);
>
> The circular point has coordinates of the root_of_2 type,
> and what i need is a point with quotient<MP_Float>;
>
> The rational points on the circle are dense, as far as my
> investigations go, and i think the function C.point_on_circle(double alpha, 
> double epsilon) for a rat_circle C from the LEDA package would solve my
> problem ( 
> http://www.informatik.uni-trier.de/~naeher/Professur/LEDA/doc/MANUAL/rat_circle.html
>  )
>
> Does anyone have an idea how this could work, or even better:
> can anyone share the LEDA source code for this function?? ;)
>
> mfg, Wolfgang