使用SQLserver采用贝塞尔函数低通滤波对读入的数据进行谐波分析-use SQL server using low-pass Bessel filter function to read data Harmonic Analysis

fortran 编写的巴特沃斯滤波程序，可以实现低通滤波，高通滤波，带通滤波，作者是李建平。-fortran program written Butterworth filter, can achieve low-pass filtering, high pass filter, band-pass filter, the author is Li Jianping.