CGAL users discussion list

[Ben Supnik <>]

Hi Guys,

Right -- having a check in the debug code to catch this compiler flag is 
a nice thing...when I had rounding math off (the default on OS X) with 
3.1 the problem manifest itself in low level precondition failures deep 
in the code. :-(

cheers
Ben

Shamyl Zakariya wrote:
> Thanks!
>
> I already had 4.2 installed ( owing to the iPhone dev SDK ) but on the 
> command line usr/bin/gcc and /usr/bin/c++ pointed to 4.0 -- I reassigned 
> the symlinks and rebuilt. THat being said, the real key -- what I didn't 
> realize -- was that since CGAL appears to be mostly headers anyway, my 
> files which include cgal headers need to be built with -frounding-math.
>
> Turning on that flag for those files has fixed the problem.
>
> And, hopefully with 4.2 it will optimize better!
>
> Thanks everybody,
>
>
> On May 27, 2009, at 8:50 AM, Sylvain Pion wrote:
>
> > Shamyl Zakariya wrote:
> > > I just installed CGAL 3.4 ( was using 3.1 ) and on running my app,
> > > CGAL terminates with the following error during static initialization:
> > > terminate called after throwing an instance of 
> > > 'CGAL::Assertion_exception'
> > >  what():  CGAL ERROR: assertion violation!
> > > Expr: -CGAL_IA_MUL(-1.1, 10.1) != CGAL_IA_MUL(1.1, 10.1)
> > > File: /usr/local/include/CGAL/Interval_nt.h
> > > Line: 154
> > > Explanation: Wrong rounding: did you forget the -frounding-math option
> > > if you use GCC?
> > > This is on Mac OS X, 10.5.7
> > > So, assuming I made some sort of mistake during the configuration of
> > > CGAL, I redownloaded the tarball and reconfigured it as such:
> > > # cmake . -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=FALSE
> > > And I'm seeing the following during configuration, which implies to me
> > > that the build system is automatically adding -frounding-math...
> > > -- Targetting Unix Makefiles
> > > -- Using /opt/local/bin/c++ compiler.
> > > -- DARWIN_VERSION=9
> > > -- Mac Leopard detected
> > > -- USING CMake version: 2.6.4
> > > -- System: Darwin
> > > -- USING GCC_VERSION = '4.0.1 (Apple Inc. build 5490)'
> > > -- Using gcc version 4 or later. Adding -frounding-math
> > > -- Build type: Release
> > > -- USING CXXFLAGS = ' -frounding-math -O3 -DNDEBUG'
> > > However, ever after this rebuild/reinstall my apps still die on the 
> > > assertion.
> > > (Please note, I'm not using any of the optional numeric packages, and
> > > I'm using boost 1.36, and cmake 2.6)
> >
> > I'm not sure what you mean exactly by "optional numeric packages",
> > but this check is useful as soon as you use CGAL::Interval_nt, which
> > is used in the filtered kernels (e.g. when you use Delaunay).
> >
> > This check can be disabled with -DCGAL_DISABLE_ROUNDING_MATH_CHECK
> > (though of course you should never have to do that).
> >
> > However, note that -DNDEBUG (which you have), also should disable this 
> > check.
> > Which means that the flags you see are not passed to the compilation
> > process correctly.  Note that -frounding-math is also needed when
> > compiling/installing CGAL itself.
> >
> > I'm not proficient enough in CMake to tell what can go wrong there,
> > maybe someone else can help.
> >
> >
> > Side note : Apple's g++ 4.0.1 is strongly discouraged for CGAL as soon
> > as you want to compile with optimization (you can e.g. upgrade Xcode
> > to get g++ 4.2).
> >
> > --
> > Sylvain Pion
> > INRIA Sophia-Antipolis
> > Geometrica Project-Team
> > CGAL, http://cgal.org/
> > --
> > You are currently subscribed to cgal-discuss.
> > To unsubscribe or access the archives, go to
> > https://lists-sop.inria.fr/wws/info/cgal-discuss

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