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Physical Sciences and Mathematics

Selected Works

William F. Trench

Selected Works

Eigenvalue problem

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Characterization And Properties Of $(R,S_\Sigma)$-Commutative Matrices, William F. Trench Dec 2011

Characterization And Properties Of $(R,S_\Sigma)$-Commutative Matrices, William F. Trench

William F. Trench

No abstract provided.


Characterization And Properties Of $(R,S_\Sigma)$-Commutative Matrices, William F. Trench Dec 2011

Characterization And Properties Of $(R,S_\Sigma)$-Commutative Matrices, William F. Trench

William F. Trench

Let $R=P \diag(\gamma_{0}I_{m_{0}}, \gamma_{1}I_{m_{1}}, \dots, \gamma_{k-1}I_{m_{k-1}})P^{-1}\in\mathbb{C}^{m\times m}$ and $S_{\sigma}=Q\diag(\gamma_{\sigma(0)}I_{n_{0}},\gamma_{\sigma(1)}I_{n_{1}}, \dots,\gamma_{\sigma(k-1)}I_{n_{k-1}})Q^{-1}\in\mathbb{C}^{n\times n}$, where $m_{0}+m_{1}+\cdots +m_{k-1}=m$, $n_{0}+n_{1}+\cdots+n_{k-1}=n$, $\gamma_{0}$, $\gamma_{1}$, \dots, $\gamma_{k-1}$ are distinct complex numbers, and $\sigma :\mathbb{Z}_{k}\to\mathbb{Z}_{k}= \{0,1, \dots, k-1\}$. We say that $A\in\mathbb{C}^{m\times n}$ is $(R,S_{\sigma})$-commutative if $RA=AS_{\sigma}$. We characterize the class of $(R,S_{\sigma})$-commutative matrrices and extend results obtained previously for the case where $\gamma_{\ell}=e^{2\pi i\ell/k}$ and $\sigma(\ell)=\alpha\ell+\mu \pmod{k}$, $0 \le \ell \le k-1$, with $\alpha$, $\mu\in\mathbb{Z}_{k}$. Our results are independent of $\gamma_{0}$, $\gamma_{1}$, \dots, $\gamma_{k-1}$, so long as they are distinct; i.e., if $RA=AS_{\sigma}$ for some choice of $\gamma_{0}$, $\gamma_{1}$, \dots, $\gamma_{_{k-1}}$ (all distinct), then $RA=AS_{\sigma}$ for arbitrary of …


Characterization And Properties Of Matrices With $K$-Involutory Symmetries Ii, William F. Trench Dec 2009

Characterization And Properties Of Matrices With $K$-Involutory Symmetries Ii, William F. Trench

William F. Trench

No abstract provided.


Properties Of Multilevel Block $\Alpha$-Circulants, William F. Trench Dec 2008

Properties Of Multilevel Block $\Alpha$-Circulants, William F. Trench

William F. Trench

No abstract provided.


Multilevel Matrices With Involutory Symmetries And Skew Symmetries, William F. Trench Dec 2004

Multilevel Matrices With Involutory Symmetries And Skew Symmetries, William F. Trench

William F. Trench

No abstract provided.


Characterization And Properties Of Matrices With Generalized Symmetry Or Skew Symmetry, William F. Trench Dec 2003

Characterization And Properties Of Matrices With Generalized Symmetry Or Skew Symmetry, William F. Trench

William F. Trench

No abstract provided.