CGAL users discussion list

[Martin Mörth <>]

Hello Everybody!

I am calculating distances between points and segments. I isolated a
case where the computation seems to be returning a bad value (double
that is not a number).

] typedef CGAL::Simple_homogeneous< double > CgKernel;
] 
] typedef CgKernel::FT        CgFieldNumber;
] typedef CgKernel::Point_2   CgPoint;
] typedef CgKernel::Segment_2 CgSegment;
] 
] std::stringstream text
] (
] "-2.0527819641170391e+142 1.5399153216416277e+142 1.2075326642268196e+139
" // p
] "-1.3832287034884996e+069 9.6657090977844965e+068 7.5794164096585707e+065
" // s.min
] "2509.7485796014098 1275.2576940874201 1.0" // s.max
] );
] 
] CgPoint p;
] CgSegment s;
] 
] text >> p;
] text >> s;
] 
] CgFieldNumber field_number_dist = CGAL::squared_distance( p, s );
] double dist = CGAL::to_double( field_number_dist );
] 
] assert( _fpclass( dist ) == _FPCLASS_QNAN /* Quiet NaN */ );

Approximate cartesian coordinates for the objects involved are:

] p     -1699.9804849431803 1275.2576946873996
] s.min -1824.9804849431800 1275.2576947042162
] s.max  2509.7485796014098 1275.2576940874201

The point is very close to the segment. I am not sure whether
producing a NaN is the behaviour one would have to expect given
the kernel I use. Maybe someone with more insight into the
distance calculation implementation can shed some light on this.

I am using CGAL 3.4 and VS 8.0 on Windows XP.

Thanks in advance for any help!

Martin
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