Spectral Fixed Point Method for Nonlinear Oscillation Equation with Periodic Solution

Table 2

The frequency calculated by SFPM-SDS (𝑁_SDS=5; 𝛿=10⁻¹⁶) and Runge-Kutta method.

Order; 𝑛	𝜔𝑛	𝜔R-K	Relative error; (𝜔𝑛/𝜔R-K−1)
1	1.154701	1.136775	1.6%
2	1.138810		0.18%
3	1.136445		−0.030%
4	1.136678		−0.0085%
5	1.136779		3.5𝑒−4%
6	1.136779		3.5𝑒−4%
7	1.136776		8.8𝑒−5%
8	1.136775		0.0%