why is my plot not showing?

Im trying to plot iteration on the x-axis vs error_delta on the y-axis, but nothing shows, they are inside the while loop.

%root for f(x) = cos(x)
paso = 0.5e-10;
N = 100;
x= 1.0; %initial guess.
i = 0;
eps = 1;
root_delta = 4.6; 
figure(1);
hold on;
while eps >= paso && i <= N
    y = x - (cos(x)/(-sin(x)));
    eps = abs(y-x);
    x= y;
    error_delta = abs(root_delta - x);
    i = i+1;
    disp('    root      iteration');
    disp([x',i',error_delta']);
    semilogy(i,error_delta);
    xlabel('iterations');
    ylabel('error Delta');
end
disp(y);
disp(i);

Answer 1

[Walter Roberson]

    i = i+1;
    error_delta(i) = abs(root_delta - x);
    semilogy(1:i,error_delta);
    drawnow()

[Luis Garcia]

Thank you so much! I gladly appreciate it.

Answer 2

[Image Analyst]

You need to index x and y. You're just overwriting the same scalar values so there is never an array to plot.

[Luis Garcia]

so error_delta = 0; but x is the i(for this plot), and I taught i was index at 0 already.