低通滤波器

代码说明：

低通滤波器，对数据进行平滑，也叫做最小二乘法，Savitzky-Golay算法-a particular type of low-pass filter, well-adapted for data smoothing, and termed variously Savitzky-Golay, least-squares, or DISPO (Digital Smoothing Polynomial) filters. Rather than having their properties defined in the Fourier domain and then translated to the time domain, Savitzky-Golay filters derive directly from a particular formulation of the data smoothing problem in the time domain