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## CGAL::ch_nswe_point

### Definition

The function ch_nswe_point finds the four extreme points of a given set of input points using a linear scan of the input points. That is, it determines the points with maximal y, minimal y, minimal x, and maximal x coordinates.

#include <CGAL/ch_selected_extreme_points_2.h>

template <class ForwardIterator>
void |
ch_nswe_point ( | ForwardIterator first, ForwardIterator beyond, ForwardIterator& n, ForwardIterator& s, ForwardIterator& w, ForwardIterator& e, Traits ch_traits = Default_traits)
|  | traverses the range [first,beyond). After execution, the value of n is an iterator in the range such that *n yx *it for all iterators it in the range. Similarly, for s, w, and e the inequalities *s yx *it, *w xy *it, and *e xy *it hold for all iterators it in the range.

### Requirements

Traits contains the following subset of types from the concept ConvexHullTraits_2 and their corresponding member functions that return instances of these types:

- Traits::Less_xy_2,
- Traits::Less_yx_2.

The default traits class Default_traits is the kernel in which the type ForwardIterator::value_type is defined.

### See Also

CGAL::ch_e_point
CGAL::ch_n_point
CGAL::ch_ns_point
CGAL::ch_s_point
CGAL::ch_w_point
CGAL::ch_we_point

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The CGAL Project . Tue, December 21, 2004 .