pub const GL20_NODES: [f64; 20];Expand description
Canonical 20-point Gauss–Legendre nodes on [-1, 1] (Abramowitz & Stegun
25.4), tabulated to f64 precision. Used here for the Drezner–Wesolowsky
bivariate normal CDF representation — 20 points give >30-digit accuracy for
the smooth arcsin-transformed integrand, ensuring the BVN value is exact to
f64 precision for all (h, k, ρ) — and shared with the cubic-cell B-spline
moment parity gate in [crate::gpu_kernels::cubic_bspline_moments].