Spectral Fixed Point Method for Nonlinear Oscillation Equation with Periodic Solution

Table 4

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	1.069045	1.077035	−0.74%
2	1.075638		−0.13%
3	1.076791		−0.023%
4	1.076952		−0.0077%
5	1.077020		−0.0014%
6	1.077029		−5.6𝑒−4%
7	1.077034		−9.3𝑒−5%
8	1.077035		0.0%