Plot rectangle

Usage: plot rectangle x1 y1 x2 y2

draws a rectangle with corners (x1,y1), (x2,y1), (x2,y2) and (x1,y2). This command can also be used in list mode, where x1, y1, x2 and y2 are four vector expressions. In list mode, the command can also be used without parameters. In this case a histogram bar, is drawn for each point in the list columns.