根据经纬度计算子午线收敛角，便于进行收敛角改正-calculated according to latitude and longitude meridian convergence angle, facilitate the convergence angle correction

计算子午线收敛角，可根据大地坐标系和高斯坐标系分别求得-Calculation of the meridian convergence Angle, according to the coordinate system and gaussian coordinates obtained respectively