eigenfunction

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eigenfunction

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Etymology tree

Proto-Indo-European *h2eyḱ-

Proto-Indo-European *h2eh2óyḱe

Proto-Germanic *aiganą

Proto-Germanic *aiganaz

Proto-West Germanic *aigan

Old High German eigan

Middle High German eigen

German eigen bor.

English eigen-

Old French fonction

Middle French function bor.

English function

English eigenfunction

eigenfunction (plural eigenfunctions )

(mathematics ) A function $\phi$ {\displaystyle \phi } such that, for a given linear operator $D$ {\displaystyle D}, $D\phi =\lambda \phi$ {\displaystyle D\phi =\lambda \phi } for some scalar $\lambda$ {\displaystyle \lambda } (called an eigenvalue).
- 2000, John von Neumann, E. Wigner, "On the Behaviour of Eigenvalues in Adiabatic Processes", in Hinne Hettema, transl., edited by Hinne Hettema, Quantum Chemistry: Classic Scientific Papers, World Scientific, published 1929, page 25:
  For many quantum-mechanical problems it is important to investigate the change of eigenvalues and eigenfunctions with the continuous change of one or more parameters. The case in which one knows the eigenvalues and eigenfunctions for two special values of the parameters, and is interested in the region in between is particularly interesting.
- 2005, Leonid D. Akulenko, Sergei V. Nesterov, High-Precision Methods in Eigenvalue Problems and Their Applications‎^[1], CRC Press (Chapman & Hall), page 1:
  Problems that require an investigation of eigenvalues and eigenfunctions arise in connection with numerous topics in mechanics, the theory of vibrations and stability, hydrodynamics, elasticity, acoustics, electrodynamics, quantum mechanics, etc.

function