Harmonic and monogenic functions on toroidal domains

Fuente: arXiv
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Hauptverfasser: Ashtab, Z., Morais, J., Porter, R. Michael
Format: Preprint
Veröffentlicht: 2023
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author Ashtab, Z.
Morais, J.
Porter, R. Michael
author_facet Ashtab, Z.
Morais, J.
Porter, R. Michael
contents A standard technique for producing monogenic functions is to apply the adjoint quaternionic Fueter operator to harmonic functions. We will show that this technique does not give a complete system in L2 of a solid torus, where toroidal harmonics appear in a natural way. One reason is that this index-increasing operator fails to produce monogenic functions with zero index. Another reason is that the non-trivial topology of the torus requires taking into account a cohomology coefficient associated with monogenic functions, apparently not previously identified because it vanishes for simply connected domains. In this paper, we build a reverse-Appell basis of harmonic functions on the torus expressed in terms of classical toroidal harmonics. This means that the partial derivative of any element of the basis with respect to the axial variable is a constant multiple of another basis element with subscript increased by one. This special basis is used to construct respective bases in the real L2-Hilbert spaces of reduced quaternion and quaternion-valued monogenic functions on toroidal domains.
format Preprint
id arxiv_https___arxiv_org_abs_2308_02965
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Harmonic and monogenic functions on toroidal domains
Ashtab, Z.
Morais, J.
Porter, R. Michael
Complex Variables
30G35, 31B05, 42B99
A standard technique for producing monogenic functions is to apply the adjoint quaternionic Fueter operator to harmonic functions. We will show that this technique does not give a complete system in L2 of a solid torus, where toroidal harmonics appear in a natural way. One reason is that this index-increasing operator fails to produce monogenic functions with zero index. Another reason is that the non-trivial topology of the torus requires taking into account a cohomology coefficient associated with monogenic functions, apparently not previously identified because it vanishes for simply connected domains. In this paper, we build a reverse-Appell basis of harmonic functions on the torus expressed in terms of classical toroidal harmonics. This means that the partial derivative of any element of the basis with respect to the axial variable is a constant multiple of another basis element with subscript increased by one. This special basis is used to construct respective bases in the real L2-Hilbert spaces of reduced quaternion and quaternion-valued monogenic functions on toroidal domains.
title Harmonic and monogenic functions on toroidal domains
topic Complex Variables
30G35, 31B05, 42B99
url https://arxiv.org/abs/2308.02965