Classes of Functions

In this chapter, we briefly present well-known classes of functions that will play an important role in our considerations. Of course, the list of such classes goes far beyond those discussed in this chapter. The latter classes will be overviewed (briefly) just because they are very general and commonly used. More specific classes will appear later in our story. In other words, if the main subject of the book is claimed to be prerequisites in harmonic analysis applicable to certain problems, this chapter is a kind of preliminaries to those prerequisites. Maybe the section about functions of bounded variation is special and it is therefore presented in more detail. After all, this topic has a special place in the author’s preference scale. So to say, all spaces are equal, but some spaces are more equal than others, at least, in the eyes of the author.