acb_dirichlet_zeta

Sets res to $\zeta(s)$, choosing the algorithm from $s$ and prec: exact values at integers (Bernoulli numbers for negative integers, arb_zeta_ui for positive ones), the Riemann–Siegel formula for $|\operatorname{Im}(s)| \ge 24 \, p^{3/2}$ and $|\operatorname{Re}(s)| \le 10 + p/10$ at precision $p$, the approximate functional equation (acb_dirichlet_l_fmpq_afe_jet) when $s$ is an exact real number which is a rational number of small height (in practice a dyadic number such as $1/2$ or $-3/4$) and the precision is high enough for this to be faster, and Euler–Maclaurin summation otherwise, after the reflection formula for $\operatorname{Re}(s) < 0$. The result is indeterminate if $s$ contains the pole $s = 1$.