CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

First try with this kernel:

CGAL::Simple_cartesian<CGAL::Gmpq> or
CGAL::Simple_cartesian<CGAL::Quotient<CGAL::MP_Float> if gmp is not
available on your machine.

This will deactivate the filtering layer and probably will give you
more information on where the problem is.

If you cannot solve it, then we will need more details (ideally a
minimal example showing the problem).

Sebastien.


wendsomde wrote:
> Hello,
>
> I am using CGAL 3.8 under Windows XP/Visual Studio 2008. I have first been
> using the Exact_predicates_inexact_constructions_kernel Kernel with the
> double number type but I the realized that some of my geometry operations
> returned wrong results. So I switched to the exact kernel
> CGAL::Simple_cartesian&lt;CGAL::Lazy_exact_nt&lt;CGAL::Quotient&lt;CGAL::MP_Float&gt;>>.
> For this to be possible, I had to modify some of my own code to use the CGAL
> exact number type (in this case
> CGAL::Lazy_exact_nt&lt;CGAL::Quotient&lt;CGAL::MP_Float&gt;>)  instead of
> double. Part of this code is a vertex class and a matrix class that I use
> for some computations. For exemple the operator * for multiplying a matrix
> with a vertex looks like this:
>
> template<class NumberType,class OperationsType>
> CVertex3Base&lt;NumberType,OperationsType&gt;   operator*               (
> CVertex3Base&lt;NumberType,OperationsType&gt;& oVertex,
> CMatrix4x4Base&lt;NumberType,OperationsType&gt;& oMatrix )
> {
>         CVertex3Base&lt;NumberType,OperationsType&gt; oVertex3dRet;
>         for ( int i = 0; i < 3; i++ ) {
>                 oVertex3dRet[i] = 0.0;
>                 for ( int j = 0; j < 3; j++ ) {                      
>                         oVertex3dRet[i] += oMatrix(j,i)*oVertex[j];
>                 }
>         }
>         return oVertex3dRet;
> }
>
> However, my program crashes on an "CGAL::Assertion_exception" at the first
> place I perform an arithmetic operation on the CGAL number type, in this
> case in the code
>
> oVertex3dRet[i] += oMatrix(j,i)*oVertex[j];
>
> Somewhere in my stacktrace I got 
> " Variable used before being initialized (or CGAL bug)"
>
> Could anyone tell me what I am doing wrong?
>
> --
> View this message in context: 
> http://cgal-discuss.949826.n4.nabble.com/CGAL-Assertion-exception-tp3839613p3839613.html
> Sent from the cgal-discuss mailing list archive at Nabble.com.