Elegant users forum

Hi all,

is it possible to optimize the third order dispersion of a lattice? I tried:

&optimization_term term = " MD3E#1.U1666 0 1e-1 sene " &end

but it didn't work. The matching was interrupted and the following message was posted:

Computing twiss parameters for optimization
Tracking for optimization
unknown token: MD3E#1.T1666
too few items on stack (divide)
*stop*
Problem evaluating expression: MD3E#1.U1666 0 1e-1 sene
RPN expression errors prevent optimization

I used

default_order=3,

in &run_setup and

matrix_order = 3,

in &optimization_setup

The marker MD3E#1 should not be the problem because it works properly for R16 and T166.


Does one of you know how to fix this?
Many thanks in advance for your help!

Best regards,
Matthias

Matthias,

Unfortunately elegant doesn't presently allow fitting with interior values of Uijk. It was simple to add, so if you build from source you can use the attached file to make a version that includes this feature.

Otherwise, you can try breaking up your beamline, since fitting with final values of Uijk should work.

--Michael

Hi Michael,

thanks for your help!

Best regards,
Matthias