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Klintborg, Markus
Publications (3 of 3) Show all publications
Klintborg, M. (2026). A complex Lie algebra of rotationally symmetric operators and their harmonics. The Journal of Analysis
Open this publication in new window or tab >>A complex Lie algebra of rotationally symmetric operators and their harmonics
2026 (English)In: The Journal of Analysis, ISSN 0971-3611Article in journal (Refereed) Epub ahead of print
Abstract [en]

We describe the solutions to a family of rotationally symmetric second order partial differential equations in the complex plane that arises from a four-dimensional complex Lie algebra whose spanning set generates the algebra from which such generalised harmonic functions derive. We show that every one of these solutions have a canonical series representation and retrieve those obtained in the case of Laplace and Helmholtz equation. These sums are given in confluent hypergeometric terms that asymptotically correspond to the complex exponential function.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2026
Keywords
Harmonic function, Power series, Confluent hypergeometric function, Bessel function
National Category
Mathematical sciences
Identifiers
urn:nbn:se:hb:diva-35549 (URN)10.1007/s41478-026-01073-1 (DOI)001744230400001 ()10.1007/s41478-026-01073-1 (Scopus ID)
Funder
Swedish Research Council, 2019-04878
Available from: 2026-04-22 Created: 2026-04-22 Last updated: 2026-05-06Bibliographically approved
Klintborg, M. (2022). Series representations for generalized harmonic functions in the case of three parameters. Complex Variables and Elliptic Equations, 69(4), 677-694
Open this publication in new window or tab >>Series representations for generalized harmonic functions in the case of three parameters
2022 (English)In: Complex Variables and Elliptic Equations, ISSN 1747-6933, E-ISSN 1747-6941, Vol. 69, no 4, p. 677-694Article in journal (Refereed) Published
Abstract [en]

We present a canonical series expansion for generalized harmonic functions in the open unit disc in the complex plane that generalizes that recently obtained for the class of (𝑝,𝑞)-harmonic functions. 

National Category
Mathematics
Identifiers
urn:nbn:se:hb:diva-33063 (URN)10.1080/17476933.2022.2159950 (DOI)
Available from: 2025-01-10 Created: 2025-01-10 Last updated: 2025-09-24Bibliographically approved
Klintborg, M. & Olofsson, A. (2021). A series expansion for generalized harmonic functions. Analysis and Mathematical Physics, 11(3), Article ID 122.
Open this publication in new window or tab >>A series expansion for generalized harmonic functions
2021 (English)In: Analysis and Mathematical Physics, ISSN 1664-2368, E-ISSN 1664-235X, Vol. 11, no 3, article id 122Article in journal (Refereed) Published
Abstract [en]

We consider a class of generalized harmonic functions in the open unit disc in the complex plane. Our main results concern a canonical series expansion for such functions. Of particular interest is a certain individual generalized harmonic function which suitably normalized plays the role of an associated Poisson kernel. 

National Category
Mathematics
Identifiers
urn:nbn:se:hb:diva-33062 (URN)10.1007/s13324-021-00561-w (DOI)
Funder
Lund University
Available from: 2025-01-10 Created: 2025-01-10 Last updated: 2025-09-24Bibliographically approved
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