On a class of eigenfunction identities for Hill operators

@inproceedings{Sachs1988OnAC,
  title={On a class of eigenfunction identities for Hill operators},
  author={Robert L. Sachs},
  year={1988}
}
Two very general identities are proved involving the eigenfunctions of two Hill operators and the spectrum of a third. Various specializations lead to a number of identities involving squares and fourth powers of the periodic eigenfunctions.