A development method may be regarded as a path or a procedure by which the developer proceeds from a problem of a certain class to a solution of a certain class. In trivial cases, the method may be fully algorithmic; for example, there is an algorithmic procedure for obtaining the square root of a nonnegative number to any desired degree of accuracy.
After forty years of currency the phrase "software engineering" still denotes no more then a vague and largely unfulfilled aspiration.
The beginning of wisdom for a programmer is to recognize the difference between getting his program to work and getting it right. A program which does not work is undoubtedly wrong; but a program which does work is not necessarily right. It may still be wrong because it is hard to understand; or because it is hard to maintain as the problem requirements change; or because its structure is different from the structure of the problem; or because we cannot be sure that it does indeed work.
We follow two rules in the matter of optimization: