Variation principles for an arbitrary operator. III
L. M. Delves · Mathematics of Computation · 1965
The methods, described in two previous papers, for generating variation principles for the matrix elements of Hermitian operators are extended here in several ways. The method is first extended to cover inhomogeneous equations. A defect of the original formulation, that it involved two trial functions, is removed by rewriting the principle so that one only appears. Finally, variation-iteration schemes are proposed.