Algorithm 2: Pseudo-code of computing the relation between the old and new reference lines.
1:	If flag is high
2:	calculate the unit vector of the old 1st reference line
3:	calculate the unit vector of the new 1st reference line
4:	compute the intersected angle between the two vectors
5:	compute the cross product of the two vectors
6:	If the 3rd component of the cross-product result is less than zero
7:	angle = −angle
8:	End if
9:	End if