中文说明：%IIR数字滤波器的设计 %设计一个低通数字滤波器，设计指标：通带截止角频率为ωp，阻带截止频率为ωs，通带最大衰减为δp，阻带最小衰减为δs %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%冲激响应不变法%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% clc; clear all; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%利用巴特沃斯设计低通模拟滤波器%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% wp = 0.2*pi; ws = 0.3*pi; Deltap = -1; Deltas = -15;%低通数字滤波器设计指标 TS = 1;%采样时间TS Wp = wp/TS; Ws = ws/TS; DeltaP = Deltap; DeltaS = Deltas; %求取模拟滤波器的设计指标 %确定巴特沃斯的阶数N和截止频率Ωc N = log((10^(-DeltaP/10)-1)/(10^(-DeltaS/10)-1))/(2*log(Wp/Ws)); N = ceil(N); %模拟滤波器的阶数N Wc = vpa( Ws/( ( 10^( -DeltaS/10 )-1 )^( 1/( 2*N ) ) ),5 )%模拟滤波器的截止频率Wc %%获得模拟滤波器的系统函数H（s） &n
English Description：
Design of%IIR digital filterDesign of a low pass digital filter, the design index: the passband cut-off angle frequency is p, the stop band cutoff frequency is s, the maximum attenuation is delta P, and the stop band attenuation is delta S%%%%%%%%