Version 5.0 The LEDA User Manual

14.18 Real Segments ( real segment )
1. Definition
An instance s of the data type real segment is a directed straight line segment in the
two-dimensional 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.
#include < LEDA/geo/real segment.h >
2. Types
real segment :: coord type
real segment :: point type
the coordinate type (real).
the point type (real point).
3. Creation
real segment s(const real point& p, const real point& q);
introduces a variable s of type real segment. s is initialized to
the segment [p, q].
real segment s(const real point& p, const real vector& v);
introduces a variable s of type real segment. s is initialized to
the segment [p, p + v].
Precondition: v.dim() = 2.
real segment s(real x1 , real y1 , real x2 , real y2 );
introduces a variable s of type real segment. s is initialized to
the segment [(x 1 , y 1 ), (x 2 , y 2 )].
real segment s;
introduces a variable s of type real segment. s is initialized to
the empty segment.
real segment s(const segment& s1 , int prec = 0);
introduces a variable s of type real segment initialized to the
segment s 1 . (The second argument is for compatibility with
rat segment.)
real segment s(const rat segment& s1 );
introduces a variable s of type real segment initialized to the
segment s 1 .