The Property of Kippenhahn Curves in Engineering Applications
In this paper, let and be deoted reducible companion matrices, we study the property of the Kippenhahn curve and of the numerical rang being an elliptic disc by making use of matrices Kronecker sum , Kronecker product and Hadamard product and the Kippenhahn curve continually.
X. T. Liu et al., "The Property of Kippenhahn Curves in Engineering Applications", Advanced Materials Research, Vols. 108-111, pp. 663-669, 2010