When is the numerical range of a nilpotent matrix circular?
نویسندگان
چکیده
The problem formulated in the title is investigated. The case of nilpotent matrices of size at most 4 allows a unitary treatment. The numerical range of a nilpotent matrix M of size at most 4 is circular if and only if the traces trM M and trM M are null. The situation becomes more complicated as soon as the size is 5. The conditions under which a 5 5 nilpotent matrix has circular numerical range are thoroughly discussed. 2010 Elsevier Inc. All rights reserved.
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ورودعنوان ژورنال:
- Applied Mathematics and Computation
دوره 216 شماره
صفحات -
تاریخ انتشار 2010