This chapter takes an in-depth view at IFEFFIT's data and syntax. It is more formal and complete than the previous chapter, but most of the topics here were touched on there. For those of you with some programming experience or some familiarity with FEFFIT, this chapter should not be too confusing. In some sense, IFEFFIT is a language for data analysis and this chapter describes the IFEFFIT language. As a programming languages, IFEFFIT is pretty weak, missing many key features. Since IFEFFIT is really XAFS data analysis program, I'll try not to make this sound like a programming text, and keep the examples in the previous chapter close at hand throughout this chapter.
IFEFFIT keeps a single storage areas for all its data, and gives you
access to this data through named variables. You may pick your own
variable names for your data and do simple algebraic manipulation of your
data. In the previous chapter we saw an example of this when we read in
data from a file to variables with names corresponding to the column labels
in the file, and then constructed 
(E) using simple mathematical
manipulation of this data.
