This program calculates the fractional level populations of a 5-level O II model atom, accounting only for collisional excitation/de-excitation and spontaneous emission. A nice example of solving a linear system of equations using matrix inversion. REFERENCES: "Astrophysics of Gaseous Nebulae and Active Galactic Nuclei" by Osterbrock and Ferland (2nd ed.)
bcfriesen/thermal_balance_OII
simple thermal equilibrium calcuation for a small O II model atom
FortranNOASSERTION