Second Lawson variant from HyperIdealConvergenceTest...WithBranchPoints.
- make_lawson_branch_points(): base + STELLAR subdivision (Java StellarLinear)
via CGAL Euler::add_center_vertex — a centre vertex per quad fan-connected to
its 4 corners (6 centres, 24 triangles, 36 edges). The 6 centres are IDEAL
vertices (b=0, v_idx=-1); θ_e=π on the 12 base edges, θ_e=π/2 on the 24 spokes.
- BranchPointsGoldenVector_JavaXVal: newton_hyper_ideal converges to the Java
golden (per symmetry class @1e-4):
original vertices → 1.3169579
base edges → 2.2924317
spoke edges → 0 (the π/2 spokes collapse to ideal)
Key insight: Java's index-based θ split (first 12 edges π, rest π/2) is
geometric — base edges vs stellar spokes — so the symmetry shortcut applies.
createLawsonHyperelliptic() NOT ported: needs a reader for the Java
conformal-data XML (lawson_curve_source.xml) + a port of
HyperIdealHyperellipticUtility, and its golden vector is not class-symmetric.
Documented as a deferred task.
243/243 cgal tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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