function star ( xc, yc, r, color )
%
%  We need 10 equally spaced angles, but we have to ask for 11.
%  Also, we shift by pi/2 so the star points upward.
%
  a = pi / 2 + linspace ( 0, 2 * pi, 11 );
%
%  We need the cosines and sines to create our xlist and ylist.
%
  ca = cos ( a );
  sa = sin ( a );
%
%  Create a circle of radius r.
%
  xlist = r * ca;
  ylist = r * sa;
%
%  Shrink alternate points, to form the star.
%
  xlist(2:2:10) = xlist(2:2:10) / (2*(1+sin(pi/10)));
  ylist(2:2:10) = ylist(2:2:10) / (2*(1+sin(pi/10)));
%
%  Shift the star to have center (xc,yc).
%
  xlist = xc + xlist;
  ylist = yc + ylist;
%
%  Ready to draw it.
%
  fill ( xlist, ylist, color );

  return
end
