pub fn kompaneets_step_nonlinear(
grid: &FrequencyGrid,
delta_n_old: &[f64],
theta_e: f64,
theta_z: f64,
dtau: f64,
) -> Vec<f64>Expand description
Perform one implicit step of the NONLINEAR Kompaneets equation on Δn.
Allocating convenience wrapper around the inplace solver. Used by tests;
production code calls kompaneets_step_coupled_inplace directly.