matlab编程实现二阶切比雪夫Ⅰ型低通滤波器,要求滤除1000HZ和4500HZ的...答:freqz_m.m文件 function[db,mag,pha,grd,w]=freqz_m(b,a)[H,w]=freqz(b,a,1000,'whole');mag=abs(H);db=20*log10((mag+eps)/max(mag));pha=angle(H);grd=grpdelay(pha);dir2par.m文件 function [C,B,A] = dir2par(b,a)M=length(b);N=length(a);[r1,p1,C]=residuez...