Functional Analysis is a core process in systems engineering used to translate and decompose high-level system requirements into a set of detailed, lower-level functions. This systematic process identifies what the system must do to meet the stakeholder needs defined in the requirements. It involves breaking down complex functions into simpler, manageable sub-functions until they are detailed enough to be assigned to specific system components (hardware, software, or personnel). The output, often called a functional architecture or detailed function criteria, serves as a crucial input for the subsequent design and implementation phases, ensuring that all initial requirements are met by the final system.

1. National Institute of Standards and Technology (NIST). (2018). Systems Security Engineering: Considerations for a Multidisciplinary Approach in the Engineering of Trustworthy Secure Systems (NIST Special Publication 800-160

Vol. 1).

Section 3.2.2

System Requirements Definition Process: This section describes the process of transforming "the stakeholder

user-oriented view of desired services

capabilities

and conditions into a technical view of a required system." This transformation is the essence of functional analysis

which derives the functional criteria from the initial requirements.

2. Massachusetts Institute of Technology (MIT) OpenCourseWare. (2005). 16.885J Aircraft Systems Engineering

Lecture 5: Functional Analysis and Decomposition.

Slide 3: The lecture notes explicitly state

"Functional analysis is the process of translating system requirements into a detailed description of the functions that the system will have to perform." This directly corresponds to the question's definition.

3. National Aeronautics and Space Administration (NASA). (2016). NASA Systems Engineering Handbook (NASA/SP-2016-6105 Rev 2).

Section 4.3

Technical Requirements Definition: This section details the process of deriving and decomposing parent requirements into a more detailed set of technical requirements. It states

"The set of derived technical requirements results from the analysis of the required behavior of the system (functional analysis)..." This confirms that functional analysis is the method used to create detailed criteria from initial requirements.