POLYGON command

Syntax: POLYGON xpoly ypoly xdata ydata key
Qualifiers: \INSIDE, \OUTSIDE
Defaults: \INSIDE

The POLYGON command creates a vector, key, which will have the same length as the input vectors, xdata and ydata. By default, key[i] = 1 if the point (xdata[i],ydata[i]) is inside the polygon defined by input vectors xpoly and ypoly, otherwise key[i] = 0. If the \OUTSIDE qualifier is used, key[i] = 0 if the point (xdata[i],ydata[i]) is inside the polygon, otherwise key[i] = 1.

Example

 GENERATE\RANDOM X -5 5 2000       ! generate some "data"
 GENERATE\RANDOM Y 10 20 2000      !
 WINDOW 5                          !
 SET PLOTSYMBOL -11                ! choose unjoined point plotting symbol
 GRAPH X Y                         ! display the data graphically
 XP = {-0.5;1.2;-0.2;1.3;-3;-2}    ! the polygon vertices 
 YP = {13;13.5;16;18.5;18;14}      !
 POLYGON\OUTSIDE XP YP X Y K       !! find data points outside polygon, create key vector, K
 WINDOW 7                          !
 SET PLOTSYMBOL -11                ! choose unjoined point plotting symbol
 IDX = WHERE(K=1)                  ! choose indices of points outside polygon
 GRAPH X[IDX] Y[IDX]               ! display data without unwanted points
 SET PLOTSYMBOL 0                  ! choose no plotting symbol
 GRAPH\OVERLAY XP//{-0.5} YP//{13} ! overlay the polygon (close by appending first point)