用于计算全球地磁正常场，输入文件为高斯球谐系数。-Used to calculate the geomagnetic normal field。 input file is gaussian spherical harmonic coefficients

利用GPS观测和精密星历，采用多项式或球谐函数模型的方法进行建模，能够同时估计接收和卫星DCB，在此基础山计算电离层TEC,为导航单位提供电离层延迟改正-Using GPS observation and precise ephemeris, or methods using spherical harmonic polynomial function model to model, simultaneously estimates the reception and satellite DCB

使用2020，IGRF-13球谐系数，计算点位磁正常场。igrf.m，输入点位三维坐标(Use 2020, igrf-13 spherical harmonic coefficient to calculate point magnetic normal field,IGRF. M, input three-dimensional coordinates of point position)

将全球采样值通过球谐分析转化为球谐模型，可设置输出的球谐模型阶次。(The global sampling values are transformed into spherical harmonic model by spherical harmonic analysis, and the order of output spherical harmonic model can be set.)