Focal Quantities Algorithms and Center Conditions Deduction
焦点量算法与中心条件推导

For general cases, this paper gives recursive formulas for computing focal quantities by return map method, and brings in an algorithm for computing and simplication of focal quantities by formal series method. For a class of polynomial systems, an algorithm for deriving time-reversible conditions is given, and the time-reversible conditions for a quintic polynomial system are obtained.