Return the value of the Riemann zeta function on x.

def zeta(x, context=None):
    """
    Return the value of the Riemann zeta function on x.

    """
    return _apply_function_in_current_context(
        BigFloat,
        mpfr.mpfr_zeta,
        (BigFloat._implicit_convert(x),),
        context,
    )