# Function (engineering)

In engineering, a **function** is interpreted as a specific process, action or task that a system is able to perform.[1]

## In engineering design

In the lifecycle of engineering projects, there are usually distinguished subsequently: *Requirements* and *Functional specification* documents. The *Requirements* usually specifies the most important attributes of the requested system. In the *Design specification* documents, physical or software processes and systems are frequently the requested functions

## In products

For advertising and marketing of technical products, the number of functions they can perform is often counted and used for promotion. For example a calculator capable of the basic mathematical operations of addition, subtraction, multiplication, and division, would be called a "four-function" model; when other operations are added, for example for scientific, financial, or statistical calculations, advertisers speak of "57 scientific functions", etc. A wristwatch with stopwatch and timer facilities would similarly claim a specified number of functions. To maximise the claim, trivial operations which do not significantly enhance the functionality of a product may be counted.

## References

- R.Barker, C. Longman, Case Method: Function and Process Modelling, Addison-Wesley Professional, 1992.