English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We provide a sufficient condition for the numerical range of a nilpotentmatrix N to be circular in terms of the existence of cycles in an undirectedgraph associated with N. We prove that if we add to this matrix N a diagonalreal matrix D, the matrix D + N has convex numerical range. For 3 x 3 nilpotentmatrices, we strength further our results and obtain necessary and sufficientconditions for circularity and convexity of the numerical range.

On the convexity and circularity of the numerical range of nilpotent quaternionic matrices