M_PI is not defined by MSVC without _USE_MATH_DEFINES, and CellEsd.cpp is reachable from the
viewer build. The citation, so far only in CellEsd.h, now also sits at the algorithm it credits.
The other files new in rc180 under common/, image_analysis/, reader/, writer/, rugnux/ and
viewer/ use no M_* constants or POSIX-only calls (grep of the rc180 diff).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015CeEGgpKdfkCTJb3YNMJcu
(cherry picked from commit a019bc5fd2084907af9379068af3265ffe6c9ef5)
Rotation runs now estimate the standard uncertainties of the cell. Every strong integrated
observation (I > 3 sigma, unclipped, unsaturated, off ice rings) gives |q| = 1/d at its observed
centroid, which depends on the detector geometry only; q^2 = h^T G* h is linear in the reciprocal
metric, so the components of G* the point group leaves free (projected from the group's rotation
parts, any setting) are fitted by weighted linear least squares with 4-sigma rejection, and the
GoF-scaled covariance is carried analytically onto a, b, c, alpha, beta, gamma (ties give equal
e.s.d.s, fixed angles zero). Least-squares cell e.s.d.s are known to be too small (Herbstein 2000),
so the same fit is made on 8 blocks of consecutive frames and their scatter / sqrt(8) is the second
estimate; the written e.s.d. is the larger of the two per parameter. Stills get none.
Outputs: <prefix>.ins next to every .hkl (TITL, CELL at the wavelength, ZERR with Z = order of the
group, LATT/SYMM from the space group - positive LATT only with -1 at the origin - a placeholder
organic SFAC/UNIT at 18 A^3 per non-H atom, HKLF 4, END); the mmCIF gains _cell.*_esd ("." where
fixed) and _cell_measurement.reflns_used/theta_min/theta_max, and writes the cell to 4/3 decimals;
report keys CELL_ESD, CELL_ESD_LSQ, CELL_ESD_BLOCKS, CELL_ESD_BLOCK_COUNT, CELL_ESD_REFLECTIONS,
CELL_ESD_THETA_RANGE_DEG (+ dev CELL_ESD_OBSERVATIONS, CELL_DSPACING_FIT).
On 13 small-molecule sets the block scatter is 10-40x the least-squares e.s.d. and is what gets
written; it lands within ~0.3-5x of XDS's CORRECT.LP e.s.d.s. SHELXT solves from the generated
.ins and SHELXL carries ZERR into its CIF su. Costs 12 ms on a small molecule, 0.16 s on 690k
lysozyme observations.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015CeEGgpKdfkCTJb3YNMJcu
(cherry picked from commit e74a3be76261fe1b6c0ff7b80c21afc4768c46cd)
leonarski_f