I can't delete plot and line in a figure

clc
clear all
close all

h = figure;
filename = 'Newton.gif';
f = @func;
df = @dfunc;
xr = 5;
maxit = 50;
es = 0.0001;
iter = 0;
fplot(f, [-10 10])
xlabel('x axis')
ylabel('y axis')
title('Newton Raphson Method Root Tracking')
axis tight manual 
grid on
hold on
for i = 1:50
    p1 = line([xr xr],[0 f(xr)]);
    line([xr xr],[0 f(xr)])

    fprintf("xr is ")
    disp(xr)
    fprintf("f(xr) is ")
    disp(f(xr))  
    
    x = [-10 0.01 10];
    y = (x-xr).*df(xr)+f(xr);
    p2 = plot(x,y);
    plot(x,y)
    
    xrold = xr;
    xr = xr - f(xr)/df(xr);
    iter = iter + 1;
    
    
    drawnow
    frame = getframe(h);
    img = frame2im(frame);
    [imind, cm] = rgb2ind(img ,256);
    if i==1
        imwrite(imind,cm,filename, 'gif', 'Loopcount', inf);
    else
        imwrite(imind,cm,filename, 'gif', 'WriteMode', 'append');
    end
    
    if f(xr) ~= 0 
        ea = abs((xr - xrold)/xr) * 100 ;
    elseif f(xr) <= es
        break
    end
    if ea <= es || iter >= maxit
        break
    end
    delete(p1)
    delete(p2)
    pause(0.2)
end
root = xr;
fprintf("Root is")
disp(root)

Hi. I made code to track root with newton raphson method,

I wanna delete the previous line of x=xr and tangent line of f(xr)

But the delete function didn't work.

What should I do?

Answer 1

[dpb]

    ...
    p1 = line([xr xr],[0 f(xr)]);
    line([xr xr],[0 f(xr)])
    ...
    x = [-10 0.01 10];
    y = (x-xr).*df(xr)+f(xr);
    p2 = plot(x,y);
    plot(x,y)
    ...
    delete(p1)    
    delete(p2)    
    ...

I'm sure that the two handles you delete are gone; problem is you drew the same line twice for each and didn't save a handle to the second rendering so it's still there...not sure why those two were there--probably leftovers from early attempts???