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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. POMI, 2002 Volume 284, Pages 36–47 (Mi znsl1536)

This article is cited in 8 papers

Determinantal inequalities for accretive-dissipative matrices

Kh. D. Ikramov

M. V. Lomonosov Moscow State University

Abstract: A matrix $A\in M_n(\mathbf C)$ is said to be accretive-dissipative if in its Hermitian decomposition
$$ A=B+iC, \quad B=B^*, \quad C=C^*, $$
both matrices $B$ and $C$ are positive definite. Further, if $B=I_n$, then $A$ is called a Buckley matrix. The following extension of the classical Fischer inequality for Hermtian positive-definite matrices is proved.
Let \begin{math} A=\begin{pmatrix} A_{11}&A_{12} A_{21}&A_{22} \end{pmatrix} \end{math} be an accritive-dissipative matrix, $k$ and $l$ be the orders of $A_{11}$ and $A_{22}$, respectively, and let $m=\min\{k,l\}$. Then
$$ |{\det A}|\le3^m|{\det A_{11}}|\,|{\det A_{22}}|. $$
For Buckley matrices, the stronger bound
$$ |{\det}|\le\biggl(\frac{1+\sqrt{17}}4\biggr)^m|{\det A_{11}}|\,|{\det A_{22}}|. $$
is obtained.

UDC: 519.6

Received: 14.02.2002


 English version:
Journal of Mathematical Sciences (New York), 2004, 121:4, 2458–2464

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