CGAL users discussion list

[Laurent Rineau <>]

On Monday 17 December 2007 19:11:03 Maarten Moesen wrote:
> Hello,
>
> When trying a 2D mesher example of CGAL together with the exact
> constructions kernel I noticed that it doesn't compile on my PC  (CGAL
> 3.3.1 / linux32 / g++ 4.0) giving error messages summarized by:
>
> test.cpp:52: instantiated from here
> /usr/local/CGAL-3.3/include/CGAL/Lazy.h:368: error: no matching function
> for call to ‘exact(CGAL::Null_tag&)’
> /usr/local/CGAL-3.3/include/CGAL/Lazy.h:83: note: candidates are: const
> double& CGAL::exact(const double&)
> ... and so on.

> This is only when using Exact_predicates_exact_constructions_kernel. For
> Exact_predicates_inexact_constructions_kernel and
> Exact_predicates_exact_constructions_kernel_with_sqrt it compiles (and
> works :)

It is documented.

http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Mesh_2_ref/Concept_ConformingDelaunayTriangulationTraits_2.html
"Types
  ConformingDelaunayTriangulationTraits_2::FT  
   The field type. It must be a model of SqrtFieldNumberType, that is must be 
a number type supporting the operations +, -, *, /, and sqrt( · )."

As you can see, it is documented that the sqrt operator is needed.

-- 
Laurent Rineau
INRIA - Sophia Antipolis
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