此代码是用4阶龙克库塔方法求解二阶差分方程的钟摆问题，仿真了阻尼，非阻尼，有外部驱动，无外部驱动，相空间轨迹等内容。-This code is a 4-order Runge Kutta pendulum method to solve the problem of second order differential equations, simulated damping, non-damping, external drive, no external drives, phase space