 chebyshev_context.lineTo(chebyshev_client_x_center + 5, chebyshev_client_y_center - i*chebyshev_client_y_step);
        chebyshev_context.fillText(i, chebyshev_client_x_center + 5, chebyshev_client_y_center - i*chebyshev_client_y_step + 16);
    }
    chebyshev_context.strokeStyle="#000000";
    chebyshev_context.stroke();
    chebyshev_context.closePath();

    // polynomial
    var A = [];
    var B = [];
    for(var i = 0; i < chebyshev_n; ++i){
        A[i] = [];
        for(var j = 0; j < chebyshev_n;