摘要
根据常微分方程定性理论已证实存在对称于相平面原点极限环的x+F(x,x)=0型微分方程中,极限环本身可以用代数方程来表示.本文提出这种代数方程的两种类型:一种是精确的;另一种是近似的.
In this Paper, we consider the nonlinear differential equations of x+F(x, x)=0(1) type.After the existence of a limit cycle of(1), symmetry with respect to the origin on the phase plane, has been proved, and the algebraic equations of limit cycles may be obtained. The author proposes two kind of such algebraic equations: the first kind is an exact one; the second kind is an approximate one.
