

   PPoollyyggoonn DDrraawwiinngg

   AArrgguummeennttss::

        x,y: vectors containing the coordinates of the vertices
             of the polygon.

    density: density of fill pattern. NOT YET implemented.

      angle: angle of fill pattern. NOT YET implemented.

     border: the color to draw the border.  Defaults to
             `par("fg")'.  Use `border=0' to omit borders.

        ...: graphical parameters can be given as arguments to
             `polygon', must importantly,

        col: an integer specifying the color to be used in
             filling the polygon.  The default is to leave
             polygons unfilled.

   DDeessccrriippttiioonn::

        `polygon' draws the polygons whose vertices are given
        in `x' and `y'.

   SSeeee AAllssoo::

        `segments' for even more flexibility, `lines', `rect',
        `box', `abline'.

   EExxaammpplleess::

        n <- 100
        xx <- c(0:n, n:0)
        yy <- c(c(0,cumsum(rnorm(n))), rev(c(0,cumsum(rnorm(n)))))
        plot   (xx, yy, type="n", xlab="Time", ylab="Distance")
        polygon(xx, yy, col="gray", border = "red")
        title("Distance Between Brownian Motions")

