Stuck at coding newton-Rapson method

I inputed the number exp(-x) into an input and 3 into x0

but the Matlab says that Index exceeds the number of array elements, index must not exceed 1

Could you solve this problem for me, Thanks in advance.

clear all
clc

syms x;

fun=input('Enter the function as a variable of x');
f=inline(fun);

f2=diff(f(x));

x0=input('Enter the initial value of interval');
z=[];
error=10^-8;
tol=inf;
i=0;
z(1)=x0;

while tol>error
    i=i+1;
    z(i+1)=z(i)-(f(z(i))/f2(z(i)));
    error=(z(i+1)-z(i))/z(i+1);
end

[Stephen23]

Why learn how to code using deprecated functions? https://www.mathworks.com/help/matlab/ref/inline.html

Answer 1

[KSSV]

Replace this line:

f2=diff(f(x));

with

f2=inline(diff(f(x)));

[seoung gi Sin]

Thank you. It worked