space charge simulation in rings

[li.chao]

Dear Michael.

Thanks for your explanation. I did a further comparison of tune-spared from elegant and CETASim.
In elegant, still, it is a one-turn map and the space charge is set as 'nonlinear'

The particle_tunes namelist is set as:
&particle_tunes filename="<root>.nup", start_pid=1, end_pid=10000, pid_interval=1, include_x=1, include_y=1, include_s=1, start_pass=1, segment_length=500 &end

In the simulation, I set 20,000 turns to track. With the last page in *.nup, I generated this plot to compare and here is the result.

Seems like elegant results produce more noise in tune calculation, in this sense, how should I improve its? Does increasing segment_length help?

One more thing to confirm, in elegant, tune data at page 40 is found by NAFF mthod with particle trajectory betwen (19500 to 20000)?
Do I get it correct?

Many thanks Michael