Version 5.0 The LEDA User Manual

14.1 Points ( point )
1. Definition
An instance of the data type point is a point in the two-dimensional plane R 2 . We use
(x, y) to denote a point with first (or x-) coordinate x and second (or y-) coordinate y.
#include < LEDA/geo/point.h >
2. Types
point :: coord type
point :: point type
the coordinate type (double).
the point type (point).
3. Creation
point p;
introduces a variable p of type point initialized to the point
(0, 0).
point p(double x, double y);
introduces a variable p of type point initialized to the point
(x, y).
point p(vector v);
introduces a variable p of type point initialized to the point
(v[0], v[1]).
Precondition: : v.dim( ) = 2.
point p(const point& p, int prec);
introduces a variable p of type point initialized to the point
with coordinates (⌊P ∗ x⌋/P, ⌊P ∗ x⌋/P ), where p = (x, y)
and P = 2 prec . If prec is non-positive, the new point has
coordinates x and y.
4. Operations
double p.xcoord( ) returns the first coordinate of p.
double p.ycoord( ) returns the second coordinate of p.
vector p.to vector( ) returns the vector ⃗xy.
int p.orientation(const point& q, const point& r)
returns orientation(p, q, r) (see below).
double p.area(const point& q, const point& r)
returns area(p, q, r) (see below).