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Author SHA1 Message Date
Tarik Moussa
b235666725 docs: Doxygen-API + Validierungsprotokoll + Porting-Tutorial
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Für einen Mathematiker der unabhängig validieren und eigene Forschung
einbringen möchte.

Doxygen-Kommentare (code/include/):
  newton_solver.hpp — newton_euclidean(), newton_spherical(), newton_hyper_ideal()
    je mit \param, \return, \note, \see inkl. mathematischer Begründung
    (Konvexität, Vorzeichenkonvention, SparseQR-Fallback-Erklärung)
  layout.hpp — euclidean_layout(), spherical_layout(), hyper_ideal_layout()
    mit vollständiger Parameter-Doku, halfedge_uv-Semantik, Poincaré-Disk-Note

Neues Dokument:
  doc/math/validation-protocol.md
    7 reproduzierbare Checks mit konkreten Befehlen und erwartetem Output:
    0. 170 Tests, 1 Skip
    1. Gauss–Bonnet exakt (1e-10)
    2. FD-Gradientencheck < 1e-6 für alle 3 Geometrien
    3. Newton-Konvergenz < 50 Iterationen
    4. τ ∈ SL(2,ℤ)-Fundamentaldomäne (3 Invarianten)
    5. Möbius-Arithmetik (Inverse, Compose, from_three)
    6. End-to-End-Pipeline
    7. Manueller τ-Check für torus_4x4.off (Codebeispiel)

Neues Tutorial:
  doc/tutorials/add-inversive-distance.md
    Vollständiger Step-by-Step-Port von Phase 9a (Luo 2004):
    Header anlegen, Energie/Gradient implementieren, FD-Check,
    Newton-Wrapper, CMakeLists, Java-Referenzvergleich, Checkliste.

doc/getting-started.md:
  Abschnitt "Known issues": macOS-Finder-Duplikate (rm-Befehl),
  Warnung "First build 30–90s" (Tarball-Extraktion)

README.md:
  Zwei neue Links in der Dokumentationstabelle (validation-protocol,
  tutorial)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-18 01:19:44 +02:00
Tarik Moussa
3f124eb071 feat(phase4): HyperIdeal Newton solver, SparseQR fallback, examples, docs
Phase 4 complete — 87 CGAL tests pass, 2 skipped.

Newton solver (phase4a):
- hyper_ideal_hessian.hpp: symmetric FD Hessian (O(ε²), PSD by convexity)
- newton_hyper_ideal(): Newton + backtracking for the HyperIdeal functional
- detail::solve_with_fallback(): optional bool* fallback_used parameter
- solve_linear_system(): public API exposing LDLT→SparseQR fallback

SparseQR fallback tests (SparseQRFallback.*):
- FullRankSystem_CorrectSolution: LDLT path, fallback_used=false
- SingularMatrix_FallbackActivated: zero-pivot → QR activated, fallback_used=true
- Euclidean_ClosedMeshNoPinConverges: gauge-mode null space handled via QR

HyperIdeal Newton tests (NewtonSolver.HyperIdeal_*):
- ConvergesTriangleAllVariable, ResultFieldsConsistent,
  ConvergesTetrahedron, SparseQRFallbackNoCrash
- Natural-target base point (b=1.0, a=0.5) — x=0 is degenerate in log-space

Pipeline tests (test_pipeline.cpp):
- End-to-end: all three geometries, mesh I/O round-trip, solve+export

Example programs (code/examples/):
- example_euclidean.cpp:   headless Euclidean pipeline
- example_hyper_ideal.cpp: headless HyperIdeal pipeline
- example_viewer.cpp:      interactive libigl viewer with jet colour map

README:
- Mathematical scope table: C++ vs Java original (18 rows)
- "For mathematicians" section: mental model, step-by-step new-functional
  guide, half-edge traversal snippets, recommended reading

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-13 00:11:25 +02:00
Tarik Moussa
e70689d29f feat(phase4a+4b): Newton solver + CGAL mesh I/O
Phase 4a — newton_solver.hpp:
  - newton_euclidean(): SimplicialLDLT on H (PSD); solves H·Δx = −G
  - newton_spherical(): SimplicialLDLT on −H (NSD→PSD); solves (−H)·Δx = G
  - Backtracking line search (halving α up to 20×) for global convergence
  - NewtonResult struct: x, iterations, grad_inf_norm, converged
  - 7 tests: 4 spherical (convergence, few iters, large perturbation,
    field consistency) + 3 Euclidean (triangle pinned, quad pinned,
    mixed pinned — all with natural-theta equilibrium at x=0)

Phase 4b — mesh_io.hpp:
  - read_mesh() / write_mesh(): CGAL::IO::read/write_polygon_mesh wrappers
  - load_mesh() / save_mesh(): throwing convenience versions
  - Supports OFF, OBJ, PLY (format detected by file extension)
  - 6 tests: OFF round-trip (tet + quad), OBJ round-trip, missing-file throw,
    vertex-position preservation, save/load convenience wrappers

All 75 cgal tests pass (3 skipped as before).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2026-05-12 17:35:00 +02:00