Differentil-equation

代码说明：

  模拟弹簧振动，讨论最简单的情形，一弹簧系统做横向运动，其位移由振动规律 所决定，仿真弹簧振动。(Spring vibration simulation to discuss the simplest case, a spring system as a lateral movement, the displacement is determined by the law of vibration, simulation spring vibration.)