   B2[i+1] = (spline_ys[i+1+2] - spline_ys[i+2]) / (spline_xs[i+1+2] - spline_xs[i+2]);
    }
    X2 = solved_linear(A2, B2, 4);
    
    spline_context.beginPath();
    for(var j = 1; j < w; ++j){
        var x1 = client_to_x(j-1);
        var x2 = client_to_x(j);
        var y1 = 0.0;
        var y2 = 0.0;
        if(x1 > spline_xs[0] && x1 < spline_xs[2]){
            y1 = polynomial_in_x(X1, x1, 4);
            y2 = polynomial_in_x(X1, x2, 4);
            spline_context.moveTo(x_to_client(x1), y_to_clie