Frequency formulation for nonlinear oscillators (part 1)

The perturbation method is a prevalent approach for nonlinear oscillators; however, the outcomes are only applicable to situations with weak nonlinearity. Other analytical methods, such as the variational iteration method and the homotopy perturbation method, can yield a satisfactory approximate solution; however, each method necessitates the completion of multiple calculations. Hereby is recommended a one-step frequency formulation for nonlinear oscillators, and this part 1 focuses itself on odd nonlinearity.