Plot polygon

Usage: plot polygon x1 y1 x2 y2 x3 y3 ... (normal mode)

      plot polygon [[x] y1...]                   (list mode)

Normal mode: The command draws a polygon with the given edges. At least three points must be specified.

List mode: The command draws polygons with the edges given by the vector expressions x, y1,... If no vector expressions are specified, polygons are drawn through the points of all list columns. If the x-expression is omitted (i.e. if only a single expression, y1, is given), the x-coordinates are taken from the x-column of the list. The number of list points must be three or more.