51全球地磁场计算，里面是一个C程序，用keil建一个工程，添加上这个文件，输入任意时间就可以直接从虚拟串口上看到数据了。-51 Calculation of the global geomagnetic field, which is a C program, using keil build a project to add on this document, you can enter any time directly from the virtual serial port to se