Winding number criterion for the origin to belong to the numerical range of a matrix on a loop of matrices
Cheng GuoShanhui Fan
所有作者
Cheng GuoShanhui Fan
文献摘要
Let A:[0,1]→GL(n,C) be continuous with A(0)=A(1), thus the winding number of detA is well-defined. If the winding number is not divisible by n, then the origin belongs to the numerical range of A(φ) for some φ∈[0,1].