@article { author = {Aghamollaei, Golamreza and Rezagholi, Sharifeh}, title = {On higher rank numerical hulls of normal matrices}, journal = {Wavelet and Linear Algebra}, volume = {4}, number = {1}, pages = {23-32}, year = {2017}, publisher = {Vali-e-Asr university of Rafsanjan}, issn = {2383-1936}, eissn = {2476-3926}, doi = {10.22072/wala.2017.47123.1080}, abstract = {‎In this paper‎, ‎some algebraic and geometrical properties of the rank$-k$ numerical hulls of normal matrices are investigated‎. ‎A characterization of normal matrices whose rank$-1$ numerical hulls are equal to their numerical range is given‎. ‎Moreover‎, ‎using the extreme points of the numerical range‎, ‎the higher rank numerical hulls of matrices of the form $A_1 \oplus i A_2$‎, ‎where $A_1$ and $A_2$ are Hermitian‎, ‎are investigated‎. ‎The higher rank numerical hulls of the basic circulant matrix‎ ‎are also studied‎.}, keywords = {Rank-k numerical hulls‎,Joint rank-k numerical range‎,‎Polynomial numerical hull‎,‎basic circulant matrix}, url = {https://wala.vru.ac.ir/article_23367.html}, eprint = {https://wala.vru.ac.ir/article_23367_ebbd946a37c2e6eee2b03af2d07bdd99.pdf} }