CGAL users discussion list

[Sebastian Kapfer <>]

Dear Sebastien!

On Wed, Oct 20, 2010 at 11:27:26AM +0200, Sebastien Loriot (GeometryFactory) 
wrote:
> I can see you have a 64bits machine. Mine is 32.
> I try on a 64bits machine and still you code ran without
> assertion failure.
>
> Did you used cmake to build CGAL?

Yes.

> can you try using cmake to generate the makefile to compile
> your example (you can use the script cgal_create_cmake_script to
> generate a CMakeLists.txt)

Using CMake has nothing to do with it.

In the meantime, I tried on a more modern machine. Ubuntu Lucid, GCC
4.4, AMD64, Boost 1.43, CGAL 3.7.  Same problem.

But your mention of your 32 bit machine tripped me off.  Of course, on
AMD64, GCC uses the SSE unit to implement floating point, which has
64-bit floats all the way through, and doesn't use 80-bit floats for
registers.

> sk@noether(~/spielwiese/fast_thicken/MinimalExample)>
>  g++ -O3
> -frounding-math -mfpmath=387 -lCGAL -odistance_browsing
> distance_browsing.cpp 
> sk@noether(~/spielwiese/fast_thicken/MinimalExample)>
> ./distance_browsing 
> sk@noether(~/spielwiese/fast_thicken/MinimalExample)>
>  g++ -O3
> -frounding-math -mfpmath=sse -lCGAL -odistance_browsing
> distance_browsing.cpp 
> sk@noether(~/spielwiese/fast_thicken/MinimalExample)>
> ./distance_browsing 
> terminate called after throwing an instance of
> 'CGAL::Assertion_exception'
>   what():  CGAL ERROR: assertion violation!
>   Expr: new_rd >= copy_rd
>   File:
>   
> /opt/cgal/3.7_boost1.40/include/CGAL/Orthogonal_incremental_neighbor_search.h
>   Line: 267
>   Aborted

(see http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html)

So it seems CGAL works when using 80-bit floats, but not with true
64-bit floats?

-- 
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