用matlab来制作卫星绕地球做周期运动的动画，改变卫星的角速度的初值，可以画出圆形，椭圆形，逃逸轨迹。-Using matlab to produce satellites orbiting the earth to do periodic motion animation, change the initial angular velocity of the satellite, you can draw round, oval, escape trajectory.

用于产生轨道角动量OAM的示意图和场强图-this code can generate the plot of orbital angular momentum