What is Functional Decomposition

Functional decomposition is a method of analysis that dissects a complex process to show its individual elements. It is used to facilitate the understanding and management of large and/or complex processes and can be used to help solve problems and aid in the development of business operations, computer programming, machine learning and a variety of other fields.

Breaking Down Functional Decomposition

Functional decomposition has its origin in mathematics, where it refers to the process of analyzing the links and relationships between all the components that create a functional relationship so that the original function may be recomposed. At is essence, functional decomposition takes something complicated and simplifies it.

Functional Decomposition Applications

Functional decomposition has applications in variety of disciplines, such as systems engineering, software architecture, database theory, machine learning, knowledge representation and signal processing. 

Practically, functional decomposition is used by engineers to describe the steps taken in the act of breaking down the function of a device, process, or system into its basic components. At the result of such an analysis, a functional decomposition diagram will detail the all the functions involved (tasks and sub-tasks and how they work together), and may address problems that have been found, as well as suggest solutions to those problems.

Functional decomposition is especially important to programming. Once a diagram has been created coding may begin, as the programmer may then work on the most basic components first and then build out an application. As such, functional decomposition helps focus and simplify the programming process. One drawback, however, is that functional decomposition can be especially labor intensive and time consuming.

Functional Decomposition Diagrams

The individual elements of the process and their hierarchical relationship to each other are commonly displayed in a diagram called a functional decomposition diagram. Other common business methods for simplifying complex problems and processes include decision trees, which allow users to consider multiple possible solutions to a problem, and flow charts, which show the sequence of a process.

Functional Decomposition Steps

The process of functional decomposition can be broken down into several steps. The use of functional decomposition diagram is key to this step.

  1. Find the basic function: What is the basic task a device or process must succeed at?
  2. List the essential sub-functions: These sub-functions are instrumental to the success of the basic function.
  3. List the next tier of sub-functions: These sub-functions serve the upper level sub-functions.
  4. Inspect the diagram: If there are functions that have been omitted add them to the diagram.