 
introduces a line l passing through the points $$p and $$q.
Line l is directed from $$p to $$q.
 
 
introduces a line l passing through point $$p with
direction $$d.
 
 
introduces a line l passing through point $$p and
oriented by $$v.
 
 
returns the line supporting the segment $$s,
oriented from source to target.
 
 
returns the line supporting the ray $$r, with the
same orientation.


 
Test for equality: two lines are equal, iff they have a non empty intersection and the same direction.  

 
Test for inequality.  

 
returns the orthogonal projection of $$p on l.  

 returns an arbitrary point on l. It holds point(i) = point(j), iff i=j. 

 returns true iff line l is degenerated to a point. 

 
returns true iff p lies on l. 

 
returns the plane perpendicular to l passing through $$p.  

 returns the line with opposite direction. 

 returns a vector having the same direction as l. 
 
 returns the direction of l.  

 
returns the line obtained by applying $$t on a point on l and the direction of l. 