Approximate Methods In Engineering Design

In design we mostly handle approximate data. Complex functions can often be
replaced by simpler approximate ones yielding results within acceptable levels
of errors. We must, however, have some idea of the magnitude and direction of
the errors thus introduced. A common technique is to replace a complex
function by a series which can be made to converge on the true value of the
function. Using the first few terms of such an expansion enables us to obtain
approximate answers good enough for practical purposes. (See Table 1.1,
p. 3, and Tables 1.2 and 1.3, pp. 29, 30.)