load(draw);
draw2d(terminal=svg,file_name="Bicorn",
  color=black,font="Times",font_size=15,nticks=75,proportional_axes=xy,
  user_preamble="set termoption enhanced; set mxtics; set mytics;set key at 5.5,7",
  xtics_axis=false,ytics_axis=false,grid=true,xrange=[-1.1,1.1],yrange=[-.1,1.1],
  xaxis=true,yaxis=true,axis_top=true,axis_bottom=true,axis_left=true,axis_right=true,
  line_width=2,/*label(["x",1.,0.1],["y",0.1,1.]),*/xlabel="x",ylabel="y",
  xtics={["-a",-1],["0",0],["a",1]},ytics={["0",0],["a/3",1/3],["a",1]},
  color=red,key="",parametric( sin(t), cos(t)**2 * (2+cos(t))/(3+sin(t)**2) ,t,-%pi,%pi)
 );