def zeta(x, q, tolerance):
"""The Hurwitz zeta function, or the Riemann zeta function of two
arguments.
``x`` must be greater than one and ``q`` must be positive.
This function repeatedly computes subsequent partial sums until
convergence, as decided by ``tolerance``.
"""
try:
from scipy.special import zeta as _zeta
return _zeta(x, q)
except ImportError:
z = 0
z_prev = -float("inf")
k = 0
while abs(z - z_prev) > tolerance:
z_prev = z
z += 1 / ((k + q) ** x)
k += 1
return z
def zeta(x, q, tolerance):
return _zeta(x, q)
def zeta(x, q, tolerance):
return _zeta(x, q)
