Geodesic
How to distinguish between the latently real matrices and the block quaternions?
Zapiski Nauchnykh Seminarov POMI, Computational methods and algorithms. Part XXIV, Tome 395 (2011), pp. 61-66 
Kh. D. Ikramov. How to distinguish between the latently real matrices and the block quaternions?. Zapiski Nauchnykh Seminarov POMI, Computational methods and algorithms. Part XXIV, Tome 395 (2011), pp. 61-66. http://geodesic.mathdoc.fr/item/ZNSL_2011_395_a4/
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Voir la notice du chapitre de livre provenant de la source Math-Net.Ru

Let a complex $n\times n$ matrix $A$ be unitarily similar to its entrywise conjugate matrix $\overline A$. If the unitary matrix $P$ in the relation $\overline A=P^*AP$ can be chosen symmetric (skew-symmetric), then $A$ is called a latently real matrix (respectively, a generalized block quaternion). Only these two cases are possible if $A$ is a (unitarily) irreducible matrix. The following question is discussed: How to find out whether the given $A$ is a latently real matrix or a generalized block quaternion?

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