"walking backwards." The final point reached, at the end of the segment corresponding to the equation's constant term, is the terminus.

A line is then launched from the origin at some angle , reflected off of each line segment at a right angle (not necessarily the "natural" angle of reflection), and refracted at a right angle through the line through each segment (including a line for the zero coefficients) when the angled path does not hit the line segment on that line. The vertical and horizontal