Three defects in the per-frame scaling of sparse (small-molecule, weak) rotation sweeps:
1. The fulls' per-frame scale pooled sparse frames by their RAW full count, but in a
high-symmetry group with many systematic absences most usable counts stayed under the
minimum, so most frames were never fitted and kept corr = 1 beside pinned, fitted frames
(two gauges in one reference). The release step then read the gauge offset (a constant
134x on a cubic Ia-3d small-molecule sweep) as signal and gave each frame exp(kept_f * 4.9) - the e^-5
errors on a quarter of the frames, R1 0.62. A fixed box window also cannot follow a
100x absorption ramp over a few degrees, and frames under the credible floor, exempt
from the window, ran away to 1e-7.
Now each round fits every frame on its own fulls (no pooling, no minimum), and the scale
is a penalised second-difference smoother of log G (Whittaker/Eilers), each frame at
the information of its fit, lambda by cross-validation over blocks one rocking curve
wide (interleaved single frames leak through shared rocking curves and chose to follow
every frame). After convergence the existing ShrinkToRestrained hands back the per-frame
deviation its neighbour shares. Pooling and the box window are gone from the fulls loop;
the partials loop is unchanged.
2. With partial scaling off (< 50 rocking events per frame) the partials kept the
integration-time corr: no incident-flux correction and not the partiality of the
ingest-smoothed geometry, because only the partial scaling loop rewrote corr. They now
get corr = prescaling_corr / partiality at G = 1 (host, and a device kernel).
3. The flux meter (per-frame mean background) jumped 30x between neighbouring frames of a
sparse sweep - on a few reflections it measures which reflections the frame holds. It
is read through the same smoother at the precision of each frame's mean.
SHELXL R1(>4sig) against the published structures, rc174-cand -> this, on the in-house
small-molecule sweeps: cubic Ia-3d 0.615 -> 0.119 (XDS 0.088); four organic sweeps
(monoclinic / orthorhombic) 0.0515 -> 0.0459, 0.0451 -> 0.0396, 0.0747 -> 0.0709,
0.0452 -> 0.0413; ISa up to 11.6 -> 31. Raw flux instead of smoothed costs 0.002-0.003 R1 on
the first two. A weak, decaying protein sweep on the fulls-only path: ISa 6.7 -> 27.1.
CPU and GPU paths agree.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB
leonarski_fandClaude Opus 5.5
495f6a97b3