load(draw);
draw2d(terminal=svg,file_name="Drini-conjugatehyperbolas",
    user_preamble="set key at 2.9,4",dimensions=[550,550],
    xtics_axis=true,ytics_axis=true,grid=true,
    xaxis=true,yaxis=true,axis_top=false,axis_bottom=false,axis_left=false,axis_right=false,
    line_width=1.5,label(["x",4,0.2],["y",0.2,4]),
    color=green,key="x^2- y^2=-1",explicit(sqrt(x^2+1),x,-4,4),
    key="",explicit(-sqrt(x^2+1),x,-4,4),
    color=blue,key="x^2- y^2= 1",explicit(sqrt(x^2-1),x,-4,-1),
    key="",explicit(-sqrt(x^2-1),x,1,4),
    explicit(sqrt(x^2-1),x,1,4),
    explicit(-sqrt(x^2-1),x,-4,-1),
    color=red,points_joined=true,line_type=dots,key="",nticks=1,
    parametric(t,t,t,-4,4),key="asymptotes",parametric(t,-t,t,-4,4)
  );