Duality

Duality as expressed by the PS formula is a central theme throughout this work. In this chapter, the special form of this duality as expressed by formulas D1 and D2 is applied to the derivation of a collection of results first investigated by Raz-Wexler on construction of biorthogonals and dual functions to W-H systems. The availability of biorthogonals opens the way to new algorithms for constructing W-H coefficient sets. In the next chapter, we compare the Raz-Wexler dual function constructions to those coming from frame theory.