Now, to assist the diligent reader in so delicate an affair, as far as brevity will permit, I have recollected, that the shrewdest pieces of this treatise were conceived in bed in a garret; at other times, for a reason best known to myself, I thought fit to sharpen my invention with hunger; and, in general, the whole work was begun, continued, and ended, under a long course of physic, and a great want of money.

Jonathan Swift, Tale of a Tub, 1697.

The controversy over the use of the singular personal pronoun, "I", in technical works continues unabated. Since the preface to a work is the one place in which the use of the word is not contentious, I will make full use of the opportunity of using it! One matter which puzzles me greatly in the argument is that the term "we" is used liberally, and without apparent censure - only "I" is somehow taboo (thus demonstrating that it is no simple issue of active/passive voice as some protagonists claim). In deference to conventionality, and on the advice of my supervisor, I have avoided the use of the word in the main text.

I hope you enjoy reading this as much as I have enjoyed producing it. On reflection it has been interesting, stimulating, and fun - ignoring the unutterable tediousness of formatting and prettifying the final version and the period in the middle of my tenure when I felt adrift with uncertainty. Don't be put off by the equations in chapter 4 and appendix 1. They are not difficult really - only a year or so ago I would have panicked if I'd seen them.

Brevity and conciseness have been two aims, which I hope have not been at either the expense of clarity, or more importantly, not resulted in oversimplification of the issues addressed. I have tried to be textually consistent throughout; English spelling is used, except in some quoted material - hence, for example, the use of both "disc" and "disk". Acronyms are used for oft-repeated terms, and I hope these make the text more readable, rather than more arcane.

In spite of the proof-reading any errors, omissions and infelicities of phraseology that still remain are my liability.