load(draw);
draw2d(terminal=svg,dimensions=[600,600],grid=true,proportional_axes=xy,
  user_preamble="set grid polar",xtics=0.2,ytics=.2,axis_top=false,
  axis_bottom=false,axis_left=false,axis_right=false,line_width=1.5,
  xrange=[-1,1],yrange=[-1,1],nticks=200,xtics_axis=true,ytics_axis=true, 
  color=blue,polar(cos(7*th),th,0,pi)
  );