in this code for finding root by newton raphson method i gave derivative of f in g. instead of giving derivative directly how can i get derivative using any code?

this is a matlab code for finding root for a function using newton raphson method... here i knew derivative of f so that i gave that in g..suppose f is a function whose derivative is little difficult to find, then how can i modify this code for using any function f?

clear
close all
clc

f= @(x) x^4 -x^2 - 80;
g =@(x) 4*x^3-2*x;

x1=3.1;
e=10^-5;
n=100;

for i =1:n
    x2= x1-(f(x1)/g(x1));
    fprintf('x%d=%.6f\n',i,x2)
    if abs(x2-x1)<e
        break
    end
    x1=x2;
end

Answer 1

[Torsten]

syms x
f = x^4-x^2-80;
g = jacobian(f);
f = matlabFunction(f)

f = function_handle with value:
    @(x)-x.^2+x.^4-8.0e+1

g = matlabFunction(g)

g = function_handle with value:
    @(x)x.*-2.0+x.^3.*4.0

[Shamila]

tsm