Some knowledge of theory is necessary if correct use is to be made of the
techniques; therefore, the authors have endeavoured to introduce some basic
theory in the expectation and hope that this will improve understanding and
incite a desire for a more thorough knowledge.
Students who master the simpler cases of a theory will find it easier to go on
to the more difficult cases when required. They will also be in a better position
to understand and be in control of calculations done by hand or calculator
and also to be able to visualise problems graphically or geometrically. It is
still true that the best way to understand a technique thoroughly is through
practice. Mathematical techniques are no exception, and for this reason the
book illustrates theory through many examples and exercises.