## FUNCTIONAL

### Functional

In mathematics, and particularly in functional analysis and the Calculus of variations, a**functional**is a function from a vector space into its underlying scalar field, or a set of functions to the real numbers. In other words, it is a function that takes a vector as its input argument, and returns a scalar. Commonly the vector space is a space of functions, thus the functional takes a function for its input argument, then it is sometimes considered a

*function of a function*. Its use originates in the calculus of variations where one searches for a function that minimizes a certain functional. A particularly important application in physics is searching ...

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### functional

#### Noun

- A function that takes a function as its argument; More precisely: A function
*y*=*f*(*x*) whose argument*x*varies in a space of (real valued, complex valued) functions and whose value belongs to a monodimensional space. An example: the definite integration of integrable real functions in a real interval. - A scalar-valued linear function on a vector space
- An object encapsulating a function pointer (or equivalent).

#### Adjective

- In good working order.
- Useful; serving a purpose, fulfilling a function
*That sculpture is not merely artistic, but also***functional**: it can be used as a hatrack.

- Only for functional purposes, notably in architecture
- ''A
**functional**construction element generally must meet higher technical but lower aesthetical requirements

- ''A
- Having semantics defined purely in terms of mathematical functions, without side-effects.
- Of a disease, such that its symptoms cannot be referred to any appreciable lesion or change of structure; opposed to organic disease, in which the organ itself is affected.

*The above text is a snippet from Wiktionary: functional*

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and as such is available under the Creative Commons Attribution/Share-Alike License.