Reference: Positions (CSC151-02, 2009F)

Building Positions

(position-new col row): MediaScheme Position Procedure. Build a new position that represents the point at (col,row).

(position-col pos): MediaScheme Position Procedure. Extract the column from position pos.
(position-row pos): MediaScheme Position Procedure. Extract the row from position pos.

(position? value): MediaScheme Position Procedure. Determine if value is a position (or can be interpreted as such).
(position-offset position hoff voff): MediaScheme Position Procedure. Create a new position, offset from position horizontally by hoff and vertically by voff.
(position-distance pos1 pos2): MediaScheme Position Procedure. Compute the distance between pos1 and pos2.
(position-interpolate pos1 pos2 percent): MediaScheme Position Procedure. Create a new position which is percent (expressed as a real number between 0 and 1) of the way from pos1 to pos2
(random-positions n cols rows): MediaScheme Position Procedure. Create n positions, each of which is difficult to predict and each with a non-negative column less than cols and a non-negative row less than rows.