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arXiv · 1911.00273

On the numerical range of some block matrices with scalar diagonal blocks

Titas Geryba·Ilya M. Spitkovsky
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Abstract

Several new verifiable conditions are established for block matrices with scalar diagonal blocks to have the numerical range equal the convex hull of at most k ellipses where k by k is the size of the smaller diagonal block. For k = 2, these conditions are also necessary, provided that the ellipses are co-centered.

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Titas Geryba, Ilya M. Spitkovsky. 2019-11-01. On the numerical range of some block matrices with scalar diagonal blocks. https://arxiv.org/abs/1911.00273

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