In 1975 one of the coauthors, Ikebe, showed that the problem of computing the zeros of the regular Coulomb wave functions and their derivatives may be reformulated as the eigenvalue problem for ...

Let A → Ar be the map that takes a positive definite matrix to its rth power, and let DAr be the Fréchet derivative of this map. It is known that ∥DAr∥ = ∥rAr−1∥ if r ≤ 1 or if r ≥ 2, and also that ...