Why

Riemann zeta zeros are computed from imaginary  - i - values.
Tried to replicate 14.1347... Cannot crack why the polar form
is shown with a negative value.

                                                         
                                                                  *     *     *
Actually, I needn't worry about sign changes:

And by sixteen, it's positive again:

The sine function cycles naturally, and larger ln factors speed things up.

                                                             *     *     *

Grapher gives standard zeta results.

It is also possible to do sums of series.