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2 Commits

Author SHA1 Message Date
Tarik Moussa
194effba97 feat(phase3f+3g): analytical Hessians + PI consolidation
Phase 3g — constants.hpp:
  - Introduce conformallab::PI and TWO_PI in a single constants.hpp
  - Remove scattered local PI/pi definitions from hyper_ideal_geometry.hpp,
    hyper_ideal_utility.hpp, euclidean_functional.hpp, mesh_builder.hpp,
    spherical_geometry.hpp (backward-compatible PI_SPHER alias kept)

Phase 3f — Euclidean Hessian (euclidean_hessian.hpp):
  - Cotangent-Laplace operator (Pinkall–Polthier 1993)
  - euclidean_cot_weights() helper + euclidean_hessian() + hessian_check_euclidean()
  - Correct Pinkall–Polthier 1/2 normalization factor
  - 8 tests: cot weights, symmetry, null-space (H·1=0), PSD, FD × 4 meshes

Phase 3f — Spherical Hessian (spherical_hessian.hpp):
  - Derives ∂α_i/∂u_j directly from the spherical law of cosines:
      ∂α1/∂l_opp  = sin(l_opp) / [sin(l_a)·sin(l_b)·sin(α1)]
      ∂α1/∂l_adj  = [cot(l_adj)·cos(α1) − cot(l_other)] / sin(α1)
    then chains with ∂l/∂λ = tan(l/2)
  - spherical_cot_weights() kept as a standalone helper (tested separately)
  - 8 tests: cot weights, symmetry, correct null-space & sign-convention
    (H·1 ≠ 0; H is NSD at equilibrium), FD × 3 meshes

All 62 cgal tests pass (3 skipped as before).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2026-05-12 17:22:28 +02:00
Tarik Moussa
8c353bb884 feat(phase3d+3e): port EuclideanCyclicFunctional + add SphericalFunctional gauge-fix
Phase 3d — EuclideanCyclicFunctional:
  • euclidean_geometry.hpp: t-value / atan2 corner-angle formula with
    centering trick (μ = (Λ̃₁₂+Λ̃₂₃+Λ̃₃₁)/6) for numerical stability
  • euclidean_functional.hpp: EuclideanMaps bundle, gradient (G_v = Θ_v − Σα_v,
    G_e = α_opp⁺ + α_opp⁻ − φ_e), 10-point GL path-integral energy,
    gradient_check_euclidean — identical halfedge convention to SphericalFunctional
  • test_euclidean_functional.cpp: 11 tests (1 skip) covering angle formula,
    right-isosceles triangle, angle sum = π, degenerate detection, gradient
    checks on triangle/quad-strip/tetrahedron/fan-5/mixed-pinned, NaN check

Phase 3e — Spherical gauge-fix:
  • spherical_gauge_shift(): Newton + backtracking line search to find t*
    where ΣG_v(x + t·1) = 0 (maximises E along the global scale direction);
    bisection used when sign change is detectable, Newton+backtrack otherwise
  • apply_spherical_gauge(): in-place wrapper
  • 3 new tests: GaugeFix_SpherTetVertexZerosSumGv, GaugeFix_ApplyInPlace,
    GaugeFix_AlreadyAtGaugeReturnsTNearZero

Total: 45 cgal tests pass, 3 skipped (@Ignore Hessian stubs, one per functional)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-12 07:39:14 +02:00