CGAL users discussion list

["Laurent Rineau (GeometryFactory)" <>]

On Friday 04 December 2009 15:21:42 Ramin H wrote:
> Thank you very much. I added  LIBS += -lCGAL -lCGAL_Core to the end of
> .pro file and that solved the problem.
> 
> I thought LIBS  += -L"/home/ramin/CGAL-3.5/lib" would be enough and
> linker will find what it needs in that folder. Does LIBS += -lCGAL
> -lCGAL_Core tell linker to use specific libraries in that folder?

-lCGAL tells the linker to find out a file named libCGAL.so and link with it. 
The -L flags that are given *before* modify the list of directories to search 
in. In your case, you added /usr/lib before -L$HOME/CGAL-3.5/lib/. If you had 
a file /usr/lib/libCGAL.so (for example from a package libcgal3-dev of 
Ubuntu), that one would be used instead of the one from the CGAL-3.5 you have 
installed in your home directory.
 
> Also, it compiled without the -frounding-math flag.

Well, it does compile without -frounding-math, but, if you compile with 
compiler optimization (which is very recommended with CGAL), your compiler 
may 
use optimization about floating point arithmetic that create bugs in CGAL 
numeric algorithms.

You should put the following in your pro file, near its beginning:

QMAKE_CXXFLAGS += -frounding-math

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/