Matrix methods in discrete-time quantum mechanics
Carl M. Bender, L. M. Simmons, Richard Stong · Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields · 1986
The operator difference equations that arise in the finite-element treatment of a quantum theory are implicit and therefore difficult to solve. By introducing a matrix formulation it is possible to circumvent the implicit character of these equations and obtain explicit closed-form solutions for arbitrary matrix elements of any operator.