CGAL users discussion list

[Benoît Presles <>]

Hello Michael,

> > > > After some tests, I think there is a bug in the min_strip_2 function (cf. 
> > > > "minStrip.cpp" to reproduce the bug).
> > > > I compute the min strip of the quadrilateral shown in figure "minStrip.png" 
> > > > and I get the following results:
> > > > -0.5818 -0.0609 0.547501
> > > > -0.5818 -0.0609 0.257432
> > > > One of these lines is printed in red.
> > > > In my point of view this result is not correct, the min strip of this set of 
> > > > points should be the green line and the line parallel to the green line 
> > > > passing through the point (0.8726,0.6539).
> > > > Thank your in advance for your help,
>
> thanks for your report. I think the patch below fixes the problem.

I have just tried to apply the patch below and I get an error:

patch --verbose < monpatch
Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|--- Min_quadrilateral_traits_2.h        (revision 59078)
|+++ Min_quadrilateral_traits_2.h        (working copy)
--------------------------
Patching file Min_quadrilateral_traits_2.h using Plan A...
Hunk #1 FAILED at 215.
Hunk #2 FAILED at 227.
2 out of 2 hunks FAILED -- saving rejects to file 
Min_quadrilateral_traits_2.h.rej
done

I think it is because I do not have the same version as you of 
"Min_quadrilateral_traits_2.h" (// $Id: Min_quadrilateral_traits_2.h 
56667 2010-06-09 07:37:13Z sloriot $)


Thank you very much for your help,
Best Regards,
Benoît



> ===================================================================
> --- Min_quadrilateral_traits_2.h        (revision 59078)
> +++ Min_quadrilateral_traits_2.h        (working copy)
> @@ -215,9 +215,9 @@
>       RT
>       width_numerator(const Strip_2&  r, Cartesian_tag) const
>       {
> -      return
> +      return CGAL_NTS square(
>           r.second.dx() * (r.third.y() - r.first.y()) +
> -        r.second.dy() * (r.first.x() - r.third.x());
> +        r.second.dy() * (r.first.x() - r.third.x()));
>       }
>
>       RT
> @@ -227,16 +227,16 @@
>       RT
>       width_numerator(const Strip_2&  r, Homogeneous_tag) const
>       {
> -      return
> +      return CGAL_NTS square(
>           r.second.dx() *
>             (r.third.hy() * r.first.hw() - r.first.hy() * r.third.hw()) +
>           r.second.dy() *
> -          (r.first.hx() * r.third.hw() - r.third.hx() * r.first.hw());
> +          (r.first.hx() * r.third.hw() - r.third.hx() * r.first.hw()));
>       }
>
>       RT
>       width_denominator(const Strip_2&  r, Homogeneous_tag) const {
> -      return r.first.hw() * r.third.hw() *
> +      return CGAL_NTS square(r.first.hw()) * CGAL_NTS square(r.third.hw()) *
>           (CGAL_NTS square(r.second.dx()) + CGAL_NTS square(r.second.dy()));
>       }