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On a new identity for diagonal terms of \(2 \times 2\) matrix roots. (English) Zbl 1503.15004

Let \(M\in\mathbb{R}^{2\times 2}\) be a matrix. Under certain assumptions, the authors prove that \(M\) has an \(n\)-th root matrix \(R=(r_{ij})\) for which \(\operatorname{Re} r_{11}\operatorname{Im} r_{11}=\operatorname{Re} r_{22}\operatorname{Im} r_{22}\).

MSC:

15A16 Matrix exponential and similar functions of matrices
15A24 Matrix equations and identities

References:

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[3] P. J. Larcombe and E. J. Fennessey, A new tri-diagonal matrix invariance property,Palest. J. Math.7, 9-13 (2018). · Zbl 1375.11027
[4] P. J. Larcombe and E. J. Fennessey, A note on two rational invariants for a particular 2×2 matrix,Palest. J. Math.7, 410-413 (2018). · Zbl 1394.11023
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[7] P. J. Larcombe and E. J. Fennessey, A short graph-theoretic proof of the 2×2 matrix anti-diagonals ratio invariance with exponentiation,Palest. J. Math.10, 102-103 (2021). · Zbl 1464.15014
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[10] B.-S. Tam and P.-R. Huang, Nonnegative square roots of matrices,Lin. Alg. Appl.498, 404-440 (2016). Author information Peter J. Larcombe, Department of Computing and Mathematics, College of Engineering and Technology, University of Derby, Kedleston Road, Derby DE22 1GB, U.K. E-mail:p.j.larcombe@derby.ac.uk Eric J. Fennessey, BAE Systems Surface Ships Ltd., HM Naval Base, Portsmouth PO1 3NJ, U.K. E-mail:eric.fennessey@baesystems.com Lee Rawlin, 4, Scarbrough Avenue, Skegness PE25 2SY, U.K. E-mail:leerawlin@btinternet.com James Stanton, 3, Brackley Drive, Spondon, Derby DE21 7SA, U.K. E-mail:mrstanton@hotmail.co · Zbl 1335.15042
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