Recently, an analytical solution of a quadratic nonlinear oscillator has been presented based on the harmonic balance method. By introducing a small parameter, a set of nonlinear algebraic equations have been solved which usually appear among unknown coefficients of several harmonic terms. But the method is not suitable for all quadratic oscillators. Earlier, introducing a small parameter to the frequency series, Cheung et al. modified the Lindstedt–Poincare method and used it to solve strong nonlinear oscillators including a quadratic oscillator. But due to some limitations of both parameters, a changed form of frequency-related parameter (introduced by Cheung et al.) has been presented for solving various quadratic oscillators.

最近，提出了一种基于谐波平衡法的二次非线性振荡器的解析解。通过引入一个小的参数，解决了一组非线性代数方程，这些方程通常出现在几个谐波项的未知系数中。但是该方法不适用于所有二次振荡器。早些时候，Cheung等人在频率序列中引入了一个小参数。修改了Lindstedt–Poincare方法，并将其用于解决包括二次振荡器在内的强非线性振荡器。但是由于这两个参数的某些限制，已经提出了一种改变形式的频率相关参数（由Cheung等人介绍），用于求解各种二次振荡器。