neTo(x_to_client(x2), y_to_client(y2));
    }
    polynomial_context.strokeStyle="#661100";
    polynomial_context.stroke();
    polynomial_context.closePath();

    // dots
    polynomial_context.beginPath();
    for(var i = 0; i < polynomial_n; ++i){
        polynomial_context.moveTo(x_to_client(polynomial_xs[i])-5.5, y_to_client(polynomial_ys[i])+5.5);
        polynomial_context.lineTo(x_to_client(polynomial_xs[i])+5.5, y_to_client(polynomial_ys[i])-5.5);
        polynomial_context.moveTo(x_to_client(pol