The loop's corr now lives in the group CSR's order next to the references (the partials in no group
after them), so the group means read both sequentially instead of gathering corr through the
permutation, and the corr update walks the same arrays. FitPerFrameG's filters, which do not change
over the loop, are applied once into a per-frame ScalingFit list with the reference-independent
factors precomputed (FitScalingFrames). ReferenceWeight is inline, and the group means are no longer
pre-filled with NaN serially.
Same values, same operations in the same order: p.hkl and the merged and unmerged MTZ data are
byte-identical on lysozyme, cytochrome C, myoglobin, a small-molecule set and 4nwv. On 4nwv (Apple
M6, 12 threads) the partial scaling iterations take 3-4x less time, ~18 s -> ~6 s over 168
iterations.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
