%Funktion f, deren Nullstelle bestimmt werden soll
function y = f_newton(sigma)

S_0 = 9780;
r = 0.0015;
K = 10000;
T = 1;
N = 1000;

d1 = (log(S_0/K)+(r+sigma^2/2)*T)/(sigma*sqrt(T));
d2 = (log(S_0/K)+(r-sigma^2/2)*T)/(sigma*sqrt(T));
Callpreis = S_0*int_simpson(d1,N)-K*exp(-r*T)*int_simpson(d2,N);
y = Callpreis-553;
