一类无界算子的二次数值域和谱

邱汶汶,齐雅茹

The Quadratic Numerical Range and the Spectrum of Some Unbounded Block Operator Matrices

Wenwen Qiu,Yaru Qi

图 6 $ k = \frac{1}{2}, \delta = 1.05, \xi = 4, \varphi = 5, \lambda_{1} = 0.82, \lambda_{2} = 3.25, \lambda_{3} = 4.26 $