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radiation-transport

Monte Carlo particle and radiation transport

Geant4, MCNP

SystemTechniques · 6Primitives · 30 radiation-transport Batch checkpoint restartdistributed · medium: Large batch jobs (end-of-day, settlement, payroll runs) that checkpoint and restart idempotentlyB rep topologygeometry · medium: Boundary representation: solids as shells, faces, loops, edges and vertices with geometry attachedSolid boolean operationsgeometry · medium: Union, intersection and difference of solids: classify, split and merge faces robustlyWavefront ray scheduling (stage que…graphics · medium: Split the per-item loop into small stage kernels joined by memory queues, so each launch runs one kind of work on a full, compacted batch.›Nurbsgeometry · medium: B-splines and NURBS curves and surfaces: knot vectors, de Boor evaluation, knot insertionSurface surface intersectiongeometry · medium: Intersect parametric surfaces by marching with subdivision and Newton refinementBounding volume hierarchyphysics · low: Binary tree of nested bounding boxes; prunes overlap and ray queries to O(log n) for any size distribution, and supports cheap insert/remove for moving objects.›Ray primitive intersectiongeometry · low: Ray-triangle (Moller-Trumbore, watertight), ray-AABB slab and ray-sphere testsSpline interpolationnumerics · low: Linear, bilinear/trilinear and cubic spline interpolation on grids and tablesVoxel ray traversal ddagraphics · low: Amanatides-Woo grid DDA to step rays through voxels for picking, shadows and collisionCollective communicationml-training · low: The family of group exchanges (broadcast, reduce, all-gather, reduce-scatter, all-to-all) and the latency-plus-bytes cost model that picks ring, tree or direct algorithms by message size and topology.›Alias method samplingnumerics · low: Vose alias tables: O(1) sampling from a discrete distribution after O(n) setupImportance samplingnumerics · low: Sample from a proposal distribution and reweight to cut Monte Carlo varianceMonte Carlo integrationnumerics · low: Estimate an expectation by averaging random samples; error falls as σ/√N in any dimension, and variance reduction (antithetic, control variates, importance sampling) shrinks σ.›PRNGs (PCG, xoshiro)numerics · low: Small, fast, statistically strong non-cryptographic generators: PCG32 and xoshiro256**, with seeding, parallel streams and unbiased ranges.›Reproducible reductionnumerics · low: Order-independent floating-point sums (fixed order, Kahan, binned) for bit-for-bit reproducibilityIdempotency keysfinance · low: Client-chosen unique key per logical operation, stored with a request fingerprint and the final response, so retries replay the first result instead of acting twice.›Write-ahead logstorage · low: Append each change to a checksummed sequential log and fsync it before touching data pages; the basis of crash durability in nearly every database.›Cron schedulingsystems · low: Cron expression parsing and next-fire-time computation, with catch-up and time-zone rulesExact geometric predicatesgeometry · low: Robust orient and incircle tests with adaptive-precision floats (Shewchuk) or exact arithmeticHalf edge meshgraphics · low: Half-edge mesh connectivity for editable polygon meshesGPU compute shadersml-training · low: The vendor-neutral GPU launch model of Metal, Vulkan and WebGPU: a grid of workgroups, shared memory, barriers and subgroups, driven by recorded command buffers.›+ 14 more primitives

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