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Branch of mathematical analysis dealing with functionals, or functions of functions. It emerged as a distinct field in the 20th century, when it was realized that diverse mathematical processes, from arithmetic to calculus procedures, exhibit very similar properties. A functional, like a function, is a relationship between objects, but the objects may be numbers, vectors, or functions. Groupings of such objects are called spaces. Differentiation is an example of a functional because it defines a relationship between a function and another function (its derivative). Integration is also a functional. Functional analysis focuses on classes of functions, such as those that can be differentiated or integrated.
This entry comes from Encyclopædia Britannica Concise. For the full entry on functional analysis, visit Britannica.com.
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