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Download as PDF; Printable version; In other projects ... This is a list of functional analysis topics. See also: Glossary of functional analysis. Hilbert space ...
In the definition, the functional derivative describes how the functional [()] changes as a result of a small change in the entire function (). The particular form of the change in ρ ( x ) {\displaystyle \rho (x)} is not specified, but it should stretch over the whole interval on which x {\displaystyle x} is defined.
In mathematics, the (linear) Peetre theorem, named after Jaak Peetre, is a result of functional analysis that gives a characterisation of differential operators in terms of their effect on generalized function spaces, and without mentioning differentiation in explicit terms.
Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (for example, inner product, norm, or topology) and the linear functions defined on these spaces and suitably respecting these structures.
Closed graph theorem (functional analysis) Closed range theorem; Cohen–Hewitt factorization theorem; Commutant lifting theorem; Commutation theorem for traces; Continuous functional calculus; Convex series; Cotlar–Stein lemma
Functional principal component analysis (FPCA) is a statistical method for investigating the dominant modes of variation of functional data. Using this method, a random function is represented in the eigenbasis, which is an orthonormal basis of the Hilbert space L 2 that consists of the eigenfunctions of the autocovariance operator .
The idea of a functional calculus is to create a principled approach to this kind of overloading of the notation. The most immediate case is to apply polynomial functions to a square matrix, extending what has just been discussed. In the finite-dimensional case, the polynomial functional calculus yields quite a bit of information about the ...
In functional analysis, a state of an operator system is a positive linear functional of norm 1. States in functional analysis generalize the notion of density matrices in quantum mechanics, which represent quantum states, both mixed states and pure states. Density matrices in turn generalize state vectors, which only represent pure states.