functional decomposition


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functional decomposition

[′fəŋk·shən·əl dē‚käm·pə′zish·ən]
(control systems)
The partitioning of a large-scale control system into a nested set of generic control functions, namely the regulatory or direct control function, the optimizing control function, the adaptive control function, and the self-organizing function.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

functional decomposition

Breaking down a process into non-redundant operations. In structured programming, it provides a hierarchical breakdown of the program into the individual operations, or routines, that are required. See normalization.


Functional Decomposition of a Program
This example is ultra simplistic, but shows the hierarchical breakdown of the program into its constituent components.
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References in periodicals archive ?
Suppose an organization has the functional decomposition (greatly simplified for discussion purposes) illustrated in Table 1.
The Functional Decomposition identifies the functional data needs.
--In functional decomposition, conceptual components correspond to system functions [DeMarco 1978].
This is a kind of functional decomposition, but now we choose the lowest level in the function refinement tree, that of atomic system transactions where each transaction consists of a conceptually atomic event-response pair.
Unlike functional decomposition, it does not group event-response pairs into more abstract functions, but it groups them according to the device that originates the event.
Functional decomposition has deep implications for testing: first, it emphasizes levels of abstraction (hence, levels of testing), and second, it creates questions of integration order (top-down or bottom-up).
The integration portion of this is driven by the functional decomposition tree, where there is another top-down or bottom-up question.
Functional decomposition is also a top-down analysis and design methodology.
These three options are essentially on a grey scale from top-down functional decomposition which is process-driven, through Jackson Structured Development (JSD) to object-oriented decomposition.
While the solution looks like a traditional, top-down functional decomposition, the book also advocates a "middle-out" approach based on Essential Systems Analysis [11], and an interpretation of dataflow diagrams where each bubble represents the system response to an event.

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