Software Engineering

9.3.1 
Functional analysis
It is not possible to decompose operational or business requirements directly into 
software structural elements, such as classes. Requirements must be decomposed 
into subrequirements for which design solutions are straightforward, uncompli-
cated, and unproblematic. Therefore, the operational requirements for the software 
product must first be decomposed to identify the intermediary and root functions 
(components and units) that the software product must accomplish.
Functional analysis is the software engineering practice by which operational 
functions, expressed by the software requirements, are decomposed into transitional 
(functional component) and rudimentary (functional unit) functions. The resulting 
functional architecture identifies and specifies the complete set of functions that the 
design solution must comprise. This practice emphasizes a top-down methodology 
for breaking the problem down into a complete set of functions that the design solu-
tion must exhibit. However, the practice involves iterating up and down the func-
tional hierarchy to resolve functional complexity challenges.