tic

itmax=100;

xn=g(x);
k=0
[x xn-x]

while abs(xn-x)> tol*max(abs(x),1.0)
     if k+1>itmax
       break
     end 
     xpp=x;
     xp=xn;
     x=g(xp);
     err = (x-xp)/(1-(xp-xpp)/(x-xp)); 
     k=k+1 
     x = x -err;
     xn=g(x);     
     [x xn-x]
end  

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