function res = roemberg(f, a, b, er)
h = b - a;
qv = (h/2)*(f(a)+f(b));
k=1;
while 1
    seq = a + (1*h)/(2^k):2/2^k:a + ((2^k - 1)*h)/2^k;
    qn = (1/2)*qv+ (h/2^k)*sum(f(seq));
    if abs(qn-qv) < er
        res = qn;
        return
    else
        qv = qn;
        k = k + 1;
    end
end
end