Fundamental Theorems for Clifford Algebra-Valued Distributions in Elliptic Clifford Analysis

A fundamental theorem in Elliptic Clifford Analysis (ECA), with the standard vector Dirac operator, is presented that is valid for Clifford algebra-valued distributions. This theorem holds under fairly general conditions on the allowed singularities of the right-hand side distributions and on the region of integration. Next a specialization of this fundamental theorem is proved that forms the starting point for solving boundary value problems with distributional sources in ECA. Finally, distributional equivalents of the Residue theorem, Cauchy’s theorem and Cauchy’s integral theorem are stated.     

On the Fourier Spectra of Distributions in Clifford Analysis

In recent papers by Brackx, Delanghe and Sommen, some fundamental higher dimensional distributions have been reconsidered in the framework of Clifford analysis, eventually leading to the introduction of four broad classes of new distributions in Euclidean space. In the current paper we continue the in-depth study of these distributions, more specifically the study of their behaviour in frequency space, thus extending classical results of harmonic analysis.     

On Primitives and Conjugate Harmonic Pairs in Hermitian Clifford Analysis

The notion of a conjugate harmonic pair in the context of Hermitian Clifford analysis is introduced as a pair of specific harmonic functions summing up to a Hermitian monogenic function in an open region $\Omega $ of $\mathbb C ^n$ . Hermitian monogenic functions are special monogenic functions, which are at the core of so-called Clifford analyis, a straightforward generalization to higher dimension of the holomorphic functions in the complex plane. Under certain geometric conditions on $\Omega $ the conjugate harmonic to a given specific harmonic is explicitly constructed and the potential or primitive of a Hermitian monogenic function is determined.     

On the Integral Representation of Spherical k-Regular Functions in Clifford Analysis

We study the null solutions of iterated applications of the spherical (Atiyah-Singer) Dirac operator on locally defined polynomial forms on the unit sphere of ; functions valued in the universal Clifford algebra , here called spherical k-regular functions. We construct the kernel functions, get the integral representation formula and Cauchy integral formula of spherical k-regular functions, and as applications, the weak solutions of higher order inhomogeneous spherical (Atiyah-Singer) Dirac equations . We obtain, in particular, the weak solution of an inhomogeneous spherical Poisson equation Δ _s g = f. This work was partially supported by NNSF of China (No.10471107) and RFDP of Higher Education (No.20060486001).     

Preconditioners Based on Fundamental Solutions

We consider a new preconditioning technique for the iterative solution of linear systems of equations that arise when discretizing partial differential equations. The method is applied to finite difference discretizations, but the ideas apply to other discretizations too. If E is a fundamental solution of a differential operator P, we have E*(Pu) = u. Inspired by this, we choose the preconditioner to be a discretization of an approximate inverse K, given by a convolution-like operator with E as a kernel. We present analysis showing that if P is a first order differential operator, KP is bounded, and numerical results show grid independent convergence for first order partial differential equations, using fixed point iterations. For the second order convection-diffusion equation convergence is no longer grid independent when using fixed point iterations, a result that is consistent with our theory. However, if the grid is chosen to give a fixed number of grid points within boundary layers, the number of iterations is independent of the physical viscosity parameter. AMS subject classification (2000) 65F10, 65N22     

Automorphic Forms in Clifford Analysis

In this paper we discuss the possibility of extending the classical theory of automorphic forms to Clifford analysis within the framework of its regularity concepts. To several weights we construct with special functions from Clifford analysis Clifford-valued automorphic forms in a hypercomplex variable that are solutions of iterated homogeneous Dirac equations in $ {\shadR}^n $ , in particular, generalizations of the classical Eisenstein series and Poincaré series on the upper half-space, on spatial octants and on the unit ball within classes of polymonogenic functions.     

On the Condition Number of Integral Equations in Acoustics using Modified Fundamental Solutions

To overcome the non-uniqueness problem arising in integral equationsfor the exterior boundary-value problems for the Helmholtz equation,Jones recently suggested adding a series of outgoing waves tothe free-space fundamental solution. We present an analysison the appropriate choice of the coefficients occurring in thisseries in order to minimize the condition number of the integralequations.     

Paracomplex Hermitean Clifford Analysis

Substituting the complex structure by the paracomplex structure plays an important role in para-geometry and para-analysis. In this article we shall introduce the paracomplex structure into the realm of Clifford analysis and establish paracomplex Hermitean Clifford analysis by constructing a paracomplex Hermitean Dirac operator \({\mathcal {D}}\) and establishing the corresponding Cauchy integral formula. The theory of paracomplex Hermitean Clifford analysis turns out to be similar to that of complex Hermitean Clifford analysis which recently emerged as a refinement of the theory of several complex variables. It deserves to be pointed out that the introduction of a single operator \({\mathcal {D}}\) in the paracomplex setting has an advantage over the complex setting where complex Hermitean monogenic functions are described by a system of equations instead of being given as null-solution of a single Dirac operator as in the case of classic monogenic functions.     

On the Structure of the Taylor Series in Clifford and Quaternionic Analysis

The Fueter variables form a basis of the space of (quaternionic or Cliffordian) hyperholomorphic homogeneous polynomials of degree one, and their symmetrized products give the respective bases of spaces of hyperholomorphic homogeneous polynomials for any degree k. In the present paper we introduce new bases, i.e., new types of hyperholomorphic variables which lead to the Taylor-type series expansions reflecting the structure of the set of all (quaternionic or Cliffordian algebra-valued) hyperholomorphic functions.     

Taylor Series in Hermitean Clifford Analysis

In this paper, we consider the Taylor decomposition for h-monogenic functions in Hermitean Clifford analysis. The latter is to be considered as a refinement of the classical orthogonal function theory, in which the structure group underlying the equations is reduced from mathfrakso(2m){mathfrak{so}(2m)}to the unitary Lie algebra u(m).     

Shifted Appell Sequences in Clifford Analysis

The aim of this paper is to present a generalization of the Appell sequences within the framework of Clifford analysis called shifted Appell sequences. It consists of sequences {M _n (x)} _n ≥ 0 of monogenic polynomials satisfying the Appell condition (i.e. the hypercomplex derivative of each polynomial in the sequence equals, up to a multiplicative constant, its preceding term) such that the first term M ₀(x) = P _k (x) is a given but arbitrary monogenic polynomial of degree k defined in ${\mathbb{R}^{m+1}}$ . In particular, we construct an explicit sequence for the case ${M_0(x)=\mathbf{P}_k(\underline x)}$ being an arbitrary homogeneous monogenic polynomial defined in ${\mathbb R^m}$ . The connection of this sequence with the so-called Fueter’s theorem will also be discussed.     

Clifford分析中对偶的k-Hypergenic函数

研究了取值于实Clifford代数空间Cl_(n+1,0)(R)中对偶的k-hypergenic函数.首先,给出了对偶的k-hypergenic函数的一些等价条件,其中包括广义的Cauchy-Riemann方程.其次,给出了对偶的hypergenic函数的Cauchy积分公式,并且应用其证明了(1-n)-hypergenic函数的Cauchy积分公式.最后,证明了对偶的hypergenic函数的Cauchy积分公式右端的积分是U\Ω_2中对偶的hypergenic函数.     

The Teodorescu Operator in Clifford Analysis

Euclidean Clifford analysis is a higher dimensional function theory centred around monogenic functions,i.e.,null solutions to a first order vector valued rotation invariant differential operator (θ) ca...     

Operator Identities in q-Deformed Clifford Analysis

In this paper, we define a q-deformation of the Dirac operator as a generalization of the one dimensional q-derivative. This is done in the abstract setting of radial algebra. This leads to a q-Dirac operator in Clifford analysis. The q-integration on mathbbR^m{mathbb{R}^m}, for which the q-Dirac operator satisfies Stokes’ formula, is defined. The orthogonal q-Clifford- Hermite polynomials for this integration are briefly studied.     

复Clifford分析中的超单演函数

该文研究复Clifford分析中的超单演函数,即方程z_n Df(z)+(n-1)Qf′=0的解. 记f(z)=Pf(z)+Qf(z)e_n,f(z)∈C^2(Ω),f(z): Ω → C^{n+1},Ω C^{n+1}，得出超单演函数的几个性质.