Digital Library of Mathematical Functions
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35 Functions of Matrix ArgumentProperties

§35.4 Partitions and Zonal Polynomials

Contents

§35.4(i) Definitions

A partition \kappa=(k_{1},\dots,k_{m}) is a vector of nonnegative integers, listed in nonincreasing order. Also, |\kappa| denotes k_{1}+\dots+k_{m}, the weight of \kappa; \ell(\kappa) denotes the number of nonzero k_{j}; a+\kappa denotes the vector (a+k_{1},\dots,a+k_{m}).

The partitional shifted factorial is given by

where \left(a\right)_{{k}}=a(a+1)\cdots(a+k-1).

See Muirhead (1982, pp. 68–72) for the definition and properties of the Haar measure d\mathbf{H}. See Hua (1963, p. 30), Constantine (1963), James (1964), and Macdonald (1995, pp. 425–431) for further information on (35.4.2) and (35.4.3). Alternative notations for the zonal polynomials are C_{\kappa}(\mathbf{T}) (Muirhead (1982, pp. 227–239)), \mathcal{Y}_{\kappa}(\mathbf{T}) (Takemura (1984, p. 22)), and \Phi_{\kappa}(\mathbf{T}) (Faraut and Korányi (1994, pp. 228–236)).

§35.4(ii) Properties

Normalization

35.4.4\mathop{Z_{{\kappa}}\/}\nolimits\!\left(\boldsymbol{{0}}\right)=\begin{cases}1%
,&\kappa=(0,\dots,0),\\
0,&\kappa\neq(0,\dots,0).\end{cases}

Orthogonal Invariance

Therefore \mathop{Z_{{\kappa}}\/}\nolimits\!\left(\mathbf{T}\right) is a symmetric polynomial in the eigenvalues of \mathbf{T}.

Summation