这段代码主要是实现二阶高斯低通滤波器，本段代码全部用MATLAB语言实现的。,This code is to achieve second-order Gaussian low-pass filter, the above code to achieve the full use of the MATLAB language.

设计巴特沃斯低通和高通IIR数字滤波器，得到二阶频率级联参数-Design of Butterworth low-pass and high-pass IIR digital filters, to be cascaded second-order frequency parameter

二阶有源低通滤波器在各参数设置下的频谱分析。-Second-order active low-pass filter settings in the parameters of spectral analysis.