datum momentum_compaction_ptc.N not updating when K2 are changed

bmad-sim / bmad-ecosystem

Bmad simulation ecosystem for simulating high energy storage rings.

https://www.classe.cornell.edu/bmad/

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datum momentum_compaction_ptc.N not updating when K2 are changed #1216

Open MichaelEhrlichman opened 2 weeks ago

MichaelEhrlichman commented 2 weeks ago

The higher order momentum compaction should be changing when a K2 in a dispersive region is adjusted. However, momentum_compaction_ptc.N remain uneffected when K2 vars are adjusted.

Test case at lns in /home/ehrlichm/for_dcs/99

tao
sho data ac
cha var all_k2 @0
sho data ac

DavidSagan commented 1 week ago

@MichaelEhrlichman Is it possible for you to come up with a simpler example that takes less time? Thanks.

MichaelEhrlichman commented 6 days ago

@DavidSagan /home/ehrlichm/for_dcs/99 should be much faster now.

DavidSagan commented 3 days ago

@MichaelEhrlichman Problem is that the data does not show a dependency on k2. So if you start Tao with a lattice with k2 zero you get the same data as with a lattice with finite k2. If Tao is started with RF off (--rf command line switch) the problem goes away. I will work on this further but for now you have a work around.