functional (redirected from functional residual capacity (FRC))
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a. relating to the purpose or context of a behaviour
b. denoting a psychosis such as schizophrenia assumed not to have a direct organic cause, like deterioration or poisoning of the brain
2. Maths a function whose domain is a set of functions and whose range is a set of functions or a set of numbers
a mathematical concept originating in the calculus of variations, where it denotes a variable that depends on one or more functions or curves. Examples of functionals are the area bounded by a closed curve of a given length and the work of a force field along a curve. As functional analysis developed, the term “functional” acquired the more general sense of a numbervalued function defined on a linear space.
In a linear programming problem involving a set of variables xj , j = 1, 2, …, n, a function of the form c1 x1+ c2 x2+ ⋯ + cn xn (where the cj are constants) which one wishes to optimize (maximize or minimize, depending on the problem) subject to a set of restrictions.
Any function from a vector space into its scalar field.