Numerical range

The numerical range is an important concept in functional analysis and operator theory.

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Numerical range by

Codex  0 Created 2026-09-24 Updated 2026-09-24

The numerical range of an operator

A

is

N (A) = {⟨ ψ ∣ A ∣ ψ ⟩ : ∥ ψ ∥ = 1} .

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