lineTo(chebyshev_x_to_client(x2), chebyshev_y_to_client(y2));
    }
    chebyshev_context.strokeStyle="#661100";
    chebyshev_context.stroke();
    chebyshev_context.closePath();

    // dots
    chebyshev_context.beginPath();
    for(var i = 0; i < chebyshev_n; ++i){
        chebyshev_context.moveTo(chebyshev_x_to_client(chebyshev_xs[i])-5.5, chebyshev_y_to_client(chebyshev_ys[i])+5.5);
        chebyshev_context.lineTo(chebyshev_x_to_client(chebyshev_xs[i])+5.5, chebyshev_y_to_client(chebyshev_ys[i])-5.5)