The commands set raxis and unset raxis toggle whether the polar axis
is drawn separately from grid lines and the x axis. If the minimum of the
current rrange is non-zero (and not autoscaled), then a white circle is drawn
at the center of the polar plot to indicate that the plot lines and axes do
not reach 0. The axis line is drawn using the same line type as the plot
border. See polar (p. ), rrange (p. ), rtics (p. ), rlabel (p. ), set grid (p. ).