TeXipedia

Dagger

Represents a double dagger or diesis symbol (‡), commonly used as a secondary reference mark or footnote indicator in academic writing.

Overview

Serves as a specialized typographical mark in academic and technical documents, particularly when multiple footnotes or references need distinct markers.

  • Often used as a secondary reference mark when asterisk (*) and single dagger (†) have already been employed
  • Appears in mathematical proofs to indicate the end of a proof (though less common than QED)
  • Frequently found in linguistic notation, bibliographic references, and scholarly annotations
  • Can be paired with other symbols in a standard hierarchy: asterisk (*), dagger (†), double dagger (‡)

Examples

Using the double dagger symbol as a footnote marker in mathematical text.

f(x)‡+g(x)† where ‡ indicates twice differentiatedf(x)^{\Dagger} + g(x)^{\dagger} \text{ where } ^{\Dagger} \text{ indicates twice differentiated} 
f(x)^{\Dagger} + g(x)^{\dagger} \text{ where } ^{\Dagger} \text{ indicates twice differentiated}

Denoting the adjoint of an operator in quantum mechanics.

⟨ψ∣A‡A∣ψ⟩≥0\langle \psi | A^{\Dagger} A | \psi \rangle \geq 0 
\langle \psi | A^{\Dagger} A | \psi \rangle \geq 0

Marking special conditions in mathematical definitions.

x‡={xif x>00otherwisex^{\Dagger} = \begin{cases} x & \text{if } x > 0 \\ 0 & \text{otherwise} \end{cases} 
x^{\Dagger} = \begin{cases} x & \text{if } x > 0 \\ 0 & \text{otherwise} \end{cases}