一类四次系统奇点的中心—焦点判定

Criterion of Center-Focus about Critial Point for a Class of Fourth System

研究一类四次系统的焦点量算法 ,我们得到了这类系统的前 1 2个奇点量公式 ,并且给出了这类系统的通积分表达式及中心焦点判据 .

Au thor investigate the calculation method of the values of critical points for a class of fourth system,and we obtain the 9th focus value for this system,we also obtain the first integrating and the criterion of center focus.