Supported by the NNSF of China(Grant Nos.11761029,11461049,11371185,11661034 and 11761055);the NSF of Inner Mongolia(Grant No.2017MS0123);the key Science and Technology Program of Colleges and Universities of Inner Mogolia(Grant No.NJZY17234)
Numerical range has an important applications on spectrum distribution of operators. In this paper, we devoted to characterizing operators whose numerical range contains the origin. Some necessary and sufficient condi...