CGAL users discussion list

["Max" <>]

Sorry, the line
return CGAL::Aff_transformation_3<Kernel>
should be
return CGAL::Aff_transformation_3<typename Vector_3::R>
>Hello
>
>I need to do some coordinates transformation between severl 3d coordinate
>frames. At first I wrote the following code to do the transformation,
>
>template<typename Vector_3>
>CGAL::Aff_transformation_3<typename Vector_3::R> MakeUserCoordSysFromVectors(
>       const Vector_3& x, const Vector_3& y, const Vector_3& z )
>{
>       // make a transformation from global/default coord system
>       // to the user/local system specified by the x/y/z *UNIT*
>       // vectors denoting the user system's x/y/z axis
>       return CGAL::Aff_transformation_3<Kernel>
>               (x.x(), x.y(), x.z(),
>               y.x(), y.y(), y.z(),
>               z.x(), z.y(), z.z());
>}
>
>but I got a compiler error. To have the code compiled, I changed the code
>to this:
>
>template<typename Vector_3>
>CGAL::Aff_transformation_3<typename Vector_3::R> MakeUserCoordSysFromVectors(
>       const Vector_3& x, const Vector_3& y, const Vector_3& z )
>{
>       return CGAL::Aff_transformation_3<Kernel>
>               (CGAL::to_double(x.x()), CGAL::to_double(x.y()), 
> CGAL::to_double(x.z()),
>               CGAL::to_double(y.x()), CGAL::to_double(y.y()), 
> CGAL::to_double(y.z()),
>               CGAL::to_double(z.x()), CGAL::to_double(z.y()), 
> CGAL::to_double(z.z()));
>}
>
>yes, it got compiled and worked ok. But I think it's not good enough -
>for any exact kernel, an conversion to double and then back may lose
>the should-have exactness. How to get rid of this drawback? Is there
>any other solution more elegant?
>
>Thanks for any help.
>
>B/Rgds
>Max
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