Legendre functions of fractional degree: Transformations and evaluations

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6 Scopus citations


Associated Legendre functions of fractional degree appear in the solution of boundary value problems on wedges or in toroidal geometries, and elsewhere in applied mathematics. In the classical case when the degree is half an odd integer, they can be expressed using complete elliptic integrals. In this study, many transformations are derived, which reduce the case when the degree differs from an integer by one-third, one-fourth or one-sixth to the classical case. These transformations or identities facilitate the symbolic manipulation and evaluation of Legendre and Ferrers functions. They generalize both Ramanujan's transformations of elliptic integrals and Whipple's formula, which relates Legendre functions of the first and second kinds. The proofs employ algebraic coordinate transformations, specified by algebraic curves.

Original languageEnglish (US)
Article number0097
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number2188
StatePublished - Apr 1 2016


  • Algebraic curve
  • Algebraic transformation
  • Ferrers function
  • Legendre function
  • Toroidal function
  • Whipple's formula

ASJC Scopus subject areas

  • General Mathematics
  • General Engineering
  • General Physics and Astronomy


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