function small_polar_plot(xo,yo,rr,theta)
%tpplot-- make a small polar plot suitable for a multi-polar display.
%   tpplot(x0,y0,rho,theta) makes a closed polar plot centered at (x0,y0),
%   with radii rho and angles theta.

% transform data to Cartesian coordinates.
xx = xo + rr.*cos(theta);
yy = yo + rr.*sin(theta);

plot([xx;xx(1)],[yy;yy(1)]);

% set(gca,'XLim',[-1 1],'YLim',[-1 1],'Visible','off');
