Version 5.0 The LEDA User Manual

at point p(const point& p1 , int prec = rat point :: default precision);
introduces a variable p of type rat point initialized to the point
with homogeneous coordinates (⌊P ∗x⌋, ⌊P ∗y⌋, P ), where p 1 =
(x, y) and P = 2 prec . If prec is non-positive, the conversion
is without loss of precision, i.e., P is chosen as a sufficiently
large power of two such that P ∗ x and P ∗ y are integers.
rat point p(double x, double y, int prec = rat point :: default precision);
see constructor above with p = (x, y).
4. Operations
point p.to float( ) returns a floating point approximation of p.
rat vector p.to vector( ) returns the vector extending from the origin to p.
void p.normalize( ) simplifies the homogenous representation by dividing all
coordinates by gcd(X, Y, W ).
integer p.X( ) returns the first homogeneous coordinate of p.
integer p.Y( ) returns the second homogeneous coordinate of p.
integer p.W( ) returns the third homogeneous coordinate of p.
double p.XD( ) returns a floating point approximation of p.X( ).
double p.YD( ) returns a floating point approximation of p.Y ( ).
double p.WD( ) returns a floating point approximation of p.W ( ).
rational p.xcoord( ) returns the x-coordinate of p.
rational p.ycoord( ) returns the y-coordinate of p.
double p.xcoordD( ) returns a floating point approximation of p.xcoord( ).
double p.ycoordD( ) returns a floating point approximation of p.ycoord( ).
rat point p.rotate90(const rat point& q, int i = 1)
rat point p.rotate90(int i = 1)
returns p rotated by i × 90 degrees about q. If i > 0 the
rotation is counter-clockwise otherwise it is clockwise.
returns p rotated by i×90 degrees about the origin. If i > 0
the rotation is counter-clockwise otherwise it is clockwise.