CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Vani Murarka wrote:
> Hi CGAL Experts,
>  
> If my whole implementation uses the Exact_spherical_kernel_3 then when 
> it comes to the point of creating a sphere or a plane or doing 
> intersections, it is very very slow. However, if I create spheres, 
> planes and do intersections using Exact_spherical_kernel_3 where the 
> points were originally in Cartesian<double> and converted to 
> Exact_spherical_kernel_3 for the purpose of creating the sphere 
> and plane and doing the intersection, then it does not take long.
>  
> How do I have Exact_spherical_kernel_3 working at the same speed even if 
> my points are originally of Exact_spherical_kernel_3?
>  
I guess you have gmp on your machine, so the number type used internally
by this kernel is gmpq. When you construct a gmpq from a double, its 
size is small so computations using these numbers are fast.
When you are doing cascaded constructions using gmpq their size increase
so does the computation time.

If you provide us a minimal code sample, we can have a look at it
to see what we can speed up.

S.

> Thank you
>  
> Vani