On Thu, 22 Feb 2018, Panna Lal Patodia wrote:
> zeta(2.1) = 1.560216533503362015758917170653014234218242329871913719457665460561046377382145741481950840260305962
> to 100 decimal places.
If you literally write zeta(2.1), then python first transforms 2.1 to a
double precision number, which is not exactly equal to 2.1; then it is
transformed by mpmath to a high-precision number which differs from 2.1
after about 15-th decimal place; and then zeta of this number is
calculated. Please write the argument of zeta correctly.