Version 5.0 The LEDA User Manual

14.2 Segments ( segment )
1. Definition
An instance s of the data type segment is a directed straight line segment in the twodimensional
plane, i.e., a straight line segment [p, q] connecting two points p, q ∈ R 2 . p is
called the source or start point and q is called the target or end point of s. The length of
s is the Euclidean distance between p and q. If p = q s is called empty. We use line(s)
to denote a straight line containing s. The angle between a right oriented horizontal ray
and s is called the direction of s.
#include < LEDA/geo/segment.h >
2. Types
segment :: coord type
segment :: point type
the coordinate type (double).
the point type (point).
3. Creation
segment s(const point& p, const point& q);
segment s(const point& p, const vector& v);
introduces a variable s of type segment. s is initialized to the
segment [p, q].
introduces a variable s of type segment. s is initialized to the
segment [p, p + v].
Precondition: v.dim() = 2.
segment s(double x1 , double y1 , double x2 , double y2 );
introduces a variable s of type segment. s is initialized to the
segment [(x 1 , y 1 ), (x 2 , y 2 )].
segment s(const point& p, double alpha, double length);
introduces a variable s of type segment. s is initialized to
the segment with start point p, direction alpha, and length
length.
segment s;
introduces a variable s of type segment. s is initialized to the
empty segment.
segment s(const segment& s1 , int);
introduces a variable s of type segment. s is initialized to a
copy of s 1 .