/// \defgroup PkgConvexHull2Ref 2D Convex Hulls and Extreme Points Reference

/// \defgroup PkgConvexHull2Concepts Concepts
/// \ingroup PkgConvexHull2Ref

/// \defgroup PkgConvexHull2Traits Traits Classes
/// \ingroup PkgConvexHull2Ref

/// \defgroup PkgConvexHull2Functions Convex Hull Functions
/// \ingroup PkgConvexHull2Ref

/// \defgroup PkgConvexHull2Convexity Convexity Checking
/// \ingroup PkgConvexHull2Ref

/// \defgroup PkgConvexHull2Subsequence Hull Subsequence Functions
/// \ingroup PkgConvexHull2Ref

/// \defgroup PkgConvexHull2Extreme Extreme Point Functions
/// \ingroup PkgConvexHull2Ref

/*!
\addtogroup PkgConvexHull2Ref

\cgalPkgDescriptionBegin{2D Convex Hulls and Extreme Points,PkgConvexHull2}
\cgalPkgPicture{Convex_hull_2/fig/convex_hull.png}
\cgalPkgSummaryBegin
\cgalPkgAuthors{Susan Hert and Stefan Schirra}
\cgalPkgDesc{This package provides functions for computing convex hulls in two dimensions as well as functions for checking if sets of points are strongly convex are not. There are also a number of functions described for computing particular extreme points and subsequences of hull points, such as the lower and upper hull of a set of points.}
\cgalPkgManuals{Chapter_2D_Convex_Hulls_and_Extreme_Points,PkgConvexHull2Ref}
\cgalPkgSummaryEnd
\cgalPkgShortInfoBegin
\cgalPkgSince{1.0}
\cgalPkgBib{cgal:hs-chep2}
\cgalPkgLicense{\ref licensesGPL  "GPL"}
\cgalPkgDemo{See Bounding Volumes,bounding_volumes_2.zip}
\cgalPkgShortInfoEnd
\cgalPkgDescriptionEnd

A subset \f$S \subseteq \mathbb{R}^2 \f$ is convex if for any two points `p` and `q`
in the set the line segment with endpoints `p` and `q` is contained in \f$ S \f$.
The convex hull of a set \f$ S \f$ is the smallest convex set containing \f$ S \f$.
The convex hull of a set of points `P` is a convex polygon with vertices in `P`.
A point in `P` is an extreme point (with respect to `P`) if it is a vertex
of the convex hull of `P`.

\cgal provides functions for computing convex hulls in two dimensions as well
as functions for testing if a given set of points is strongly convex or not.
There are also a number of functions available for computing particular extreme
points in 2D and subsequences of the hull points, such as the lower hull or
upper hull of a set of points. 

\cgalClassifedRefPages

\cgalCRPSection{Assertions}

The assertion flags for the convex hull and extreme point algorithms
use `CH` in their names (<I>e.g.</I>, `CGAL_CH_NO_POSTCONDITIONS`).
For the convex hull algorithms, the postcondition
check tests only convexity (if not disabled), but not containment of the
input points in the polygon or polyhedron defined by the output points.
The latter is considered an expensive checking and can be enabled by
defining `CGAL_CH_CHECK_EXPENSIVE`.

\cgalCRPSection{Concepts}

- `ConvexHullTraits_2`

\cgalCRPSection{Traits Classes}

- `CGAL::Convex_hull_constructive_traits_2<R>`
- `CGAL::Convex_hull_traits_2<R>`

\cgalCRPSection{Convex Hull Functions}

- `CGAL::ch_akl_toussaint()`
- `CGAL::ch_bykat()`
- `CGAL::ch_eddy()`
- `CGAL::ch_graham_andrew()`
- `CGAL::ch_jarvis()`
- `CGAL::ch_melkman()`
- `CGAL::convex_hull_2()`

\cgalCRPSection{Convexity Checking Functions}

- `CGAL::is_ccw_strongly_convex_2()`
- `CGAL::is_cw_strongly_convex_2()`

\cgalCRPSection{Hull Subsequence Functions}

- `CGAL::ch_graham_andrew_scan()`
- `CGAL::ch_jarvis_march()`
- `CGAL::lower_hull_points_2()`
- `CGAL::upper_hull_points_2()`

\cgalCRPSection{Extreme Point Functions}

- `CGAL::ch_e_point()`
- `CGAL::ch_nswe_point()`
- `CGAL::ch_n_point()`
- `CGAL::ch_ns_point()`
- `CGAL::ch_s_point()`
- `CGAL::ch_w_point()`
- `CGAL::ch_we_point()`


*/

