Theorem

Plancherel Theorem

Analysis

The Plancherel Theorem is a result of harmonic analysis, proved by Michel Plancherel in 1910, establishing that the Fourier transform is a unitary operation on the real line, meaning it preserves the total energy, or L2 norm, of a function. It generalizes Parseval's Theorem, which states the analogous energy-preserving property for Fourier series, to the Fourier transform, and its unitarity is a large part of why the Fourier transform is used so widely throughout science and engineering.

Facts
Statement
The integral of the squared modulus of a function equals the integral of the squared modulus of its Fourier transform, meaning the Fourier transform preserves a function's total energy. 1
Proof Year
1910 1
Classification
Statement Form
Identity or Equation 1
Plancherel Theorem
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Has Statement Form

Equation, Concepts
Identity, Concepts

In Branch

Source Plancherel theorem (Wikipedia)

Principal Result Of

Source MacTutor History of Mathematics, University of St Andrews: Michel Plancherel

Proved By

Source Plancherel theorem (Wikipedia)
Sources
1. Plancherel theorem (Wikipedia)
  • Introduction section
    The theorem states that the integral of a function's squared modulus is equal to the integral of the squared modulus of its frequency spectrum.
  • Lead paragraph
    In mathematics, the Plancherel theorem (sometimes called the Parseval-Plancherel identity) is a result in harmonic analysis, proven by Michel Plancherel in 1910.
  • In Branch: Harmonic Analysis, Lead sentence
  • Proved By: Michel Plancherel, Lead sentence, attribution
    proven by Michel Plancherel in 1910
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MacTutor History of Mathematics, University of St Andrews: Michel Plancherel
MacTutor History of Mathematics, University of St AndrewsPrincipal Result Of: Michel Plancherel, Biography text
Quote, Principal Result Of: Michel Plancherel, Biography text
He is best known for Plancherel's theorem in harmonic analysis.
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