The ladder set a trial centre and then scored it on spots found at the starting
centre. Raw centroids do not move with the beam centre, but which spots are in
the list does: the resolution limit, the ice-ring flag, the beam-stop mask and
the strongest-N ranking are all computed against a radius. Every rung was
therefore judged on the starting centre's evidence, and the count it produced
was not a function of the centre it named.
A trial centre now gets its own azimuthal mapping, spot engines and spot cache;
the starting centre's cache is parked and restored, so a ladder that adopts
nothing leaves the run exactly as it was. Measured against standalone runs
pinned at the same centres, the ladder's score goes from a mean absolute error
of 21.8 validation frames to 0.43, and at nine pinned centres the patched and
unpatched binaries agree exactly - the change is confined to the ladder.
Scoring honestly is not by itself an improvement: with the count honest, one
crystal adopted a rung at a real 56/60 whose cell is a four-fold axis harmonic
of the standing one, and merged the supercell. A longer cell indexes more,
which is why the harmonic arbiter exists elsewhere in this file. A rung whose
primitive volume is an integer or sqrt(3) multiple of the standing cell is now
refused, and that crystal walks past both harmonics to a 60/60 rung.
Over a hundred rotation datasets no space group, cell or run status changes.
Eight merges move: one gains 126 per cent of its unique reflections, one 3.7,
five move by less than half a per cent, and one loses 3.2 - that last was
attributed separately and is the difference between two failed merges, both
peaking at a half-dataset correlation of 5 per cent, with the honest run the
slightly better of the two. Wall time rises 1.7 per cent, the cost of finding
spots again at each trial centre.
On a corpus processed from a deliberately destroyed beam centre the same change
recovers eight datasets outright on their deposited space group and cell,
restores a ninth's space-group call by returning its axial absence counts to the
values the correct geometry gives, and withdraws one adoption that had shipped a
wrong cell in the wrong crystal system at a half-dataset correlation of 0.10.
Note that only the spot-cache half of this does the work. Reading the indexer's
geometry per call rather than from construction was measured to change nothing
on a rotation ladder, because the per-frame validation dispatches to a path that
takes its geometry from the forced indexer result; it is kept because the copy
was misleading to read, not because it moves a number.
leonarski_f
3d9c8b878b