控制系统状态方程的中心焦点判定——计算机辅助公式推导

CRITERIONS OF CENTER AND FOCUS FOR THE STATE EQUATIONS OF CONTROL SYSTEMS ——Computer Aid Formula Derivation

控制系统状态方程的中心焦点判定＊——计算机辅助公式推导熊正大梁肇军（华中师范大学数学系，武汉４３００７９）关键词焦点量；积分因子；Ｔ－算子中图分类号Ｏ１７５．１２对于如下方程：ｘ＝－ｙ＋Ｘ（ｘ，ｙ），ｙ＝ｘ＋Ｙ（ｘ，ｙ），作变换ｚ＝ｘ＋ｉｙ，ｚ＝ｘ－...

This paper gives a recurrence formula to calculate focus values, which depends on computing a power series with respect to single variable.Besides, taking advantage of computer algebra systems, it gives the programs to calculate focus values. Moreover, the focus values of a class of 5th order systems is calculated.