Constant DENSITY_COEFFICIENTS 

pub const DENSITY_COEFFICIENTS: [[f64; 150]; 9];

Density variation coefficients for each species (9 species x 150 terms).

Each row is a 150-term coefficient array used in geographic_variation() to compute the fractional perturbation of species density. Species order: He, O, N2, TLB, O2, Ar, H, N, anomalous O.