jungfrauandClaude Opus 5
e11c2a2b20
The fit has ONE parameter, and it was handed to Ceres as one residual block per rocking event - 8 million of them on a large crystal. Each block is a functor, an auto-diff cost function and a loss object on the heap, and the solver then factorises an 8-million-by-one Jacobian on every iteration. It cost 13.7 s. The residual is closed-form in k. A rotation preserves length, so |p_lab| is |e_mid| whatever k is and only the z component moves; Rodrigues gives it exactly: r(k) = C + A cos(a k) - B sin(a k) = C + R cos(a k + psi) C = lambda |e|^2 / 2 + u_z (u.e), A = e_z - u_z (u.e), B = (u x e)_z with a the event's angle from the sweep centre. That is the same function the functor computes - Ceres uses the exact Rodrigues form here, so there is no small-angle branch to disagree with - and it reduces the fit to minimising a smooth function of one variable over the interval the solver was bounded to. It is scanned on a grid and then closed in by golden section; the objective's curvature jumps wherever an event crosses the Huber knee, which is why this is not a Newton iteration. The coefficients are computed in double and stored narrowed. Their rounding moves the minimiser by ~1e-10, and k is carried downstream as a float, so the committed value is the same to far more digits than anything reads. One pass over the events yields the five per-fifth partial sums, so the all-data fit and the five leave-a-fifth-out folds share it. That matters because the jackknife only runs when the fit is big enough to act on, and on a crystal that trips it the old code paid for six full solves. The partials gather ahead of it counted first and then filled instead of growing one vector by push_back tens of millions of times, which copied the whole thing on every doubling. Measured: unchanged verdict and k to five decimals on the regression crystals. Full 24-crystal battery: same space group on all 24, none failed, 15m32s -> 13m35s together with the scale/merge changes. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Jungfraujoch
Application to receive data from the PSI JUNGFRAU and EIGER detectors.
All documentation is now placed in docs/ subdirectory and for the current version hosted on Jungfraujoch Read The Docs page.