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Zapiski Nauchnykh Seminarov POMI, 2012, Volume 405, Pages 133–137
(Mi znsl5283)
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Unitary congruence to a conjugate-normal matrix
Kh. D. Ikramov M. V. Lomonosov Moscow State University, Moscow, Russia
Abstract:
A matrix $A\in M_n(\mathbb C)$ is said to be conjugate-normal if $AA^*=\overline{A^*A}.$ The following proposition (which is the congruence analog of a recent result of T. G. Gerasimova) is proved: A matrix $B\in M_n(\mathbb C)$ is unitarily congruent to a conjugate-normal matrix $A$ if and only if
$$
\mathrm{tr}[(\bar AA)^i]=\mathrm{tr}[(\bar BB)^i],\qquad i=1,\dots,n,
$$
and
$$
\|A\|_F=\|B\|_F.
$$
This proposition dramatically reduces the amount of computational work for verifying unitary congruence as compared to the case of general matrices $A$ and $B$.
Key words and phrases:
unitary similarity, unitary congruence, normal matrix, conjugate-normal matrix, Specht criterion.
Received: 15.05.2012
Citation:
Kh. D. Ikramov, “Unitary congruence to a conjugate-normal matrix”, Computational methods and algorithms. Part XXV, Zap. Nauchn. Sem. POMI, 405, POMI, St. Petersburg, 2012, 133–137; J. Math. Sci. (N. Y.), 191:1 (2013), 72–74
Linking options:
https://www.mathnet.ru/eng/znsl5283 https://www.mathnet.ru/eng/znsl/v405/p133
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Abstract page: | 257 | Full-text PDF : | 77 | References: | 42 |
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