Code:

function[p0,err,k,y]=newton(f,df,p0,delta,epsilon,max1)
%Input - f is the object function input as a string 'f'
% df is the derivative of f input as a string 'df'
% p0 is the initial approximation to a zero of f
% delta is the tolerance for p0
% epsilon is the tolerance for the function values y
% max is the maximum number of iterations
% output -p0 is the newton raphson approximation to the zero
% err is the error estimate for p0
% k is the number of iteration
% y is the function value f(p0)
for k=1:max1
p1=p0-feval(f,p0)/feval(df,p0);
err=abs(p1-p0);
relerr=2*err/(abs(p1)+delta);
p0=p1;
y=feval(f,p0);
if (err<delta)|(relerr<delta)|(abs(y)<epsilon),break,end
end

This program is the newton raphson iteration to approximate a root

of f(x)=0 given initial approximation p0 and using the iteration,

pk= pk-1 - ( f(pk-1)/ f'(pk-1) ) for k = 1,2,3 ....

Note... k and k-1 are in subscripts of p