Files
ConformalLabpp/code/include/gauss_legendre.hpp
Tarik Moussa 59a26123c8 fix(minor): all five MINOR findings — doc, accuracy, and DRY
MINOR-1 (spherical_functional.hpp:426)
  Wrong comment said "second derivative < 0 for a convex functional".
  The spherical energy is *concave* (NSD Hessian); the monotone-f argument
  applies to both convex and concave functionals equally.  Comment rewritten
  to explain the actual physics: increasing scale increases all angles and
  thus reduces Σ G_v.

MINOR-2 (spherical_functional.hpp:494-495)
  Forward finite difference O(ε) → central finite difference O(ε²):
    old: dft = (sum_Gv(t + fd_eps) - ft) / fd_eps
    new: dft = (sum_Gv(t + fd_eps) - sum_Gv(t - fd_eps)) / (2*fd_eps)
  Same cost when the extra sum_Gv(t - fd_eps) replaces the cached ft.

MINOR-3 (euclidean_functional.hpp, spherical_functional.hpp,
         inversive_distance_functional.hpp)
  New header gauss_legendre.hpp centralises the 10-point Gauss-Legendre
  nodes and weights (gl10_nodes() / gl10_weights()).  The three energy
  functions now use the shared accessors instead of duplicated local
  static arrays.

MINOR-4 (euclidean_functional.hpp, spherical_functional.hpp,
         hyper_ideal_functional.hpp, inversive_distance_functional.hpp)
  halfedge_to_index() centralised in conformal_mesh.hpp.  All four local
  aliases (eucl_hidx, spher_hidx, hidx, id_detail::hidx) now delegate to
  it as one-line wrappers; the aliases are kept for now to avoid a larger
  call-site churn, clearly documented as thin wrappers.

MINOR-5 (clausen.hpp:33-38)
  Added a comment above inits() explaining the intentional off-by-one
  return value and how it interacts with csevl() — matching the Java
  Clausen.inits() / csevl() contract.

277/277 CGAL + 26/26 pure-math tests pass, 0 failed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-31 01:17:27 +02:00

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#pragma once
// Copyright (c) 2024-2026 Tarik Moussa.
// SPDX-License-Identifier: MIT
// gauss_legendre.hpp
//
// 10-point Gauss-Legendre quadrature nodes and weights on [-1,1].
//
// Previously duplicated verbatim in:
// euclidean_functional.hpp, spherical_functional.hpp,
// inversive_distance_functional.hpp (MINOR-3 fix)
//
// Usage (integration over [0,1] via change of variables t=(1+s)/2, w=w_GL/2):
//
// const auto* s = conformallab::gl10_nodes();
// const auto* w = conformallab::gl10_weights();
// for (int k = 0; k < 10; ++k) {
// double t = (1.0 + s[k]) * 0.5;
// double wt = w[k] * 0.5;
// E += wt * dot(G(t*x), x);
// }
namespace conformallab {
/// 10-point Gauss-Legendre nodes on [1, 1].
inline const double* gl10_nodes() noexcept {
static constexpr double s[10] = {
-0.9739065285171717, -0.8650633666889845,
-0.6794095682990244, -0.4333953941292472,
-0.1488743389816312, 0.1488743389816312,
0.4333953941292472, 0.6794095682990244,
0.8650633666889845, 0.9739065285171717
};
return s;
}
/// 10-point Gauss-Legendre weights on [1, 1].
inline const double* gl10_weights() noexcept {
static constexpr double w[10] = {
0.0666713443086881, 0.1494513491505806,
0.2190863625159820, 0.2692667193099963,
0.2955242247147529, 0.2955242247147529,
0.2692667193099963, 0.2190863625159820,
0.1494513491505806, 0.0666713443086881
};
return w;
}
} // namespace conformallab