The Anderson commit before this one changed three rc176 battery results, which is why it was
reverted there. One of them is the acceleration's own doing: on a split myoglobin sweep (P2_1,
ISa 2.5) the partials loops never settle - one walks at a step of ~2e-2 for as long as it runs -
and the fulls loops walk from their first round (their cross-validated lambda moves every round,
so the map itself is not fixed). Restarting the history whenever the step grew only rebuilt a
one- or two-round history and extrapolated along the walk: the stalled loops ended somewhere
else, the pre-pass fulls smoothing window went from ~7 frames to ~1, and CC1/2 fell 0.701 -> 0.595.
Two rules now confine the acceleration to the regime it is for - a map contracting to its fixed
point:
- a loop is accelerated only once its plain step is below ten times the tolerance (1e-2);
- the first round whose weighted residual grew turns the acceleration off for the rest of the
loop (AndersonMixing::Stopped), instead of restarting it.
A loop that walks therefore stays the plain loop it was in rc176. The growth rule alone gave
CC1/2 0.625; with the onset, 0.701, as rc176.
Measured against rc176 bc191bb80 (GPU, workstation):
- myob_x06da_split: P2_1, CC1/2 0.701, d 1.81 A - as rc176; 481 -> 257 scaling iterations.
- 7qij 434 -> 126 iterations, 9v16 273 -> 101, same space group and statistics.
- ci tier (29 sets, no null model): 28 unchanged beyond noise; sum of times 580 -> 585 s
(9gdj +9 s, below).
The two other changes are NOT Anderson's and stay:
- insu_I_x06da_weak I23 -> I222: the all-observations search refuses I23 on a merge chi2 ratio
2.08 against a 1.85 bound; plain scaling converged to 1e-5 gives 2.07-2.09 and refuses it too.
Only the plain loop stopped at 1e-3 passed - the bound was set on unconverged scaling.
- 9gdj +9 s, same answer: the early beam-centre comparison's "loses beyond noise" margin
(-0.002 against 2 sigma 0.0016) moves by ~0.07 between scaling paths, so the converged loop no
longer takes the shortcut and both centres are judged on all frames; the file's centre is kept
either way.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PXc1zD1yxHqaR1DGdCTHL4
The partials and fulls scaling loops are alternating least squares that converge linearly:
over the rc176 battery's 2527 loops a round shrinks the step by a median 0.86 (partials) and
0.93 (fulls), up to 0.98, so the 1e-3 step tolerance stopped them 0.6% / 1.4% (median) and up to
17% (fulls p90) short of their fixed point, and 313 of them were stopped as "stalled" when they
were only slow - a stalled fulls loop also skipped ShrinkToRestrained.
Each round is now accelerated in log G by type-II Anderson mixing (Walker & Ni 2011), depth 5,
each frame weighted by its observation count as in the step test; frames below the credible floor
take the plain round's scale. The history is dropped when the weighted residual grows or the set
of fitted frames changes (new AndersonMixing class, unit-tested on a synthetic slow ALS loop). The
mixed scales are gauge-pinned again before the rescale, and the stop test is unchanged: it reads
the round's residual F(x) - x, so "stalled" now means a loop that does not settle under
acceleration either.
Measured (CPU, -N 8): 4nwv 311 -> 82 iterations over 9 loops, 9v16 76 iterations over 11 loops,
the same counts as the env-gated prototype on tail-solver; no history restart fired on either.
Depth 3/5/8 give 92/91/90 iterations on 4nwv. A restart on a change of the fulls loop's
cross-validated lambda was tried and gave nothing (83 vs 82). Same space group and merging
statistics on 4nwv and 9v16.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PXc1zD1yxHqaR1DGdCTHL4
leonarski_fandClaude Opus 5.5