Comments on the Numerov-Cooley and Hartree-Cooley methods for finding eigenvalues

The Numerov-Cooley and Hartree-Cooley formulae for correcting a trial eigenvalue of the Schroedinger equation are derived from linear algebra. The usual implementation of the former is noted to contain an error in the square of the step size, but in practical iteration it makes only a small change to the rate of convergence. The Ridley correction which also leads to the Hartree-Cooley formula is shown to be of second order. (orig.)