leonarski_fandClaude Opus 5.5
20ab92fcab
The same source built with and without -march=x86-64-v3 gave different results on battery sets (9zmu axis-harmonic supercell arbiter fired in one build only; 8rud resolution cut 1.69 vs 1.70 A; myob_x06da_powder_1 cut 1.07 vs 1.42 A; 7mzt short-axis first pass; lcystine_x10sa_20keV indexed vs no lattice), against the rule that no decision may depend on compiler flags. Two mechanisms, found by building the merged tree four ways (baseline, x86-64-v2, x86-64-v3, x86-64-v3 -mno-fma) with and without -ffp-contract=off and comparing p.mtz: - FMA contraction. GCC contracts a*b+c whenever the target has FMA. With -ffp-contract=off the x86-64-v3 build gives a p.mtz byte-identical to the baseline build on 8 of 9 sets (7mzt, 8rud, 9zmu, insu_I_x06da_5keV_2, myob_x06da_powder_1, myob_x10sa, cytc_x10sa, thau_x10sa_16keV), on both the GPU and the CPU build. Cost: none measurable (user core-s, CPU build, x86-64-v3 vs the same with -ffp-contract=off: 1877/1874, 3285/3253, 2212/2195 on myob/cytc/thau; GPU likewise within noise). Set project-wide for C, C++ and CUDA host code; MSVC does not contract under /fp:precise. - SIMD width. lcystine still differed: baseline and x86-64-v2 (128-bit) agreed, x86-64-v3 with or without FMA (256-bit) disagreed - Eigen's HouseholderQR in the FFT indexer's candidate refinement (PostIndexingRefinement.cpp) reduces column norms over all spots in packets of the target width. Replaced by the 3x3 normal equations summed in spot order in double. All four builds now agree on all nine sets. Changes results of the default x86-64-v3 build (contraction off); lcystine_x10sa_20keV now gives no lattice in every build (its first pass is a knife-edge: 0/60 vs 9/60 validation frames before). Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB
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.