Addendum to a paper of Craig and Goodman.
The asymptotic behaviour of a Sturm-Liouville differential equation with coefficient is investigated, where and is a nondecreasing step function tending to as . Let denote the set of those ’s for which the corresponding differential equation has a solution not tending to 0. It is proved that is an additive group. Four examples are given with , , (i.e. the set of dyadic numbers), and .
We consider the equation where and () are positive continuous functions for all and . By a solution of the equation we mean any function , continuously differentiable everywhere in , which satisfies the equation for all . We show that under certain additional conditions on the functions and , the above equation has a unique solution , satisfying the inequality where the constant does not depend on the choice of .