Hurwitz zeta function

Question

I am using the below function to compute the Hurwitz zeta function from Riemann zeta function. But I am not getting the correct results when compared with the value of Wolfram alpha Hurwitz zeta function. I am suspecting some issues with floating point errors but not sure. Can someone help me out with the explanation?

function h=hzeta(s,q)

z = zeta(s)

h = z - sum((1:(q-1)).^(-s));

where $q=1-500$ and $s=1-7.$

Thanks,

Answer 1

It's rather hard to explain your results if you don't say what your results are. For example $\zeta(2) = 1.644934067$ while $\zeta(2,3) = .3949340668 = \zeta(2) - (1/1^2 + 1/2^2)$. What do you get?