16.1 Highlights of What’s New in Version 2026.2

Here is a summary of what’s changed since release 2026.1. Historical change logs are collected in Section 16.

The major change is support for spin tracking. This is invoked by setting spin_tracking=1 in the run_setup command.

16.1.1 Bug Fixes for Elements

• Several elements (e.g., WATCH) had a bug in which incomplete filenames (e.g., %s.w1) were expanded and then saved in parameter and lattice files.
• There was a bug in EHKICK, EVKICK, and EKICKER that resulted in failure to include the path-length increase when then deflection angle was very small.

16.1.2 Bug Fixes for Commands

• The save_lattice command incorrectly handled element reflections when output_seq was non-zero. This was reported by M. Abo-Bakr (HZB).

16.1.3 New and Modified Elements

• BUMPER, CSBEND, DQCOR, EHKICK, EKICK, EVKICK, KQUAD, KQUSE, KSEXT, FMULT, ROTATE, and SOLE elements support spin tracking.
• The new POLAR element can be used to polarize the beam.
• The WATCH element will output data related to spin when spin-tracking is enabled.

16.1.4 New and Modified Commands

• The bunched_beam and bunched_beam_moments commands now support specification of the (common) spin vector.
• The modulate_elements command now supports time- and pass-based modulation delays, as well as a convenience factor for the modulation amplitude.
• The centroid, final, output, and sigma output files from run_setup include spin-related quantities when spin tracking is enabled.
• Optimization of spin-related quantities is supported.
• The particle_tunes command has the option to include spin tune.
• The moments_output command has the option to force e₁ > e₂.

16.1.5 Changes to Examples

• None.

16.1.6 Changes to Related Programs and Files

The elegant distribution includes many programs and scripts that perform computations with elegant output data, provide interfaces with other programs, or prepare data for use with elegant. These are listed in Section 11.

Changes to these tools in this release include

• Added sddsupsample, a program to up-sample particle distributions. Written by GPT-5.2-Codex guided by M. Borland.
• Added Emacs modes for command and lattice file editing. See documentation below. Written by GPT-5.2-Codex guided by M. Borland.
• Added centroid2floor, a program to combine reference floor-coordinate and centroid data to make a file with the beam path in global (floor) coordinates.