数字信号处理及matlab实现课后答案

数字信号处理及matlab实现课后1.4（1）function[f,k]=lsxj(f1,f2,k1,k2)k=min(min(k1),min(k2)):max(max(k1),max(k2));%和序列长度s1=zeros(1,length(k));s2=s1;%初始化新序列s1(find((k>=min(k1))&(k<=max(k1))==1))=f1;s2(find((k>=min(k2))&(k<=max(k2))==1))=f2;f=s1s2;stem(k,f,'filled')k1=-4:-1;f1=2*k1;k2=-4:-1;f2=[4444];k3=0:4; f3=[44444];k4=0:4; f4=[00000];k5=-8:-5;f5=0*k5;k6=5:8; f6=0*k6;holdonstem(k5,f5);[f,k]=lsxj(f1,f2,k1,k2);[f,k]=lsxj(f3,f4,k3,k4);stem(k6,f6);Title（'1.4(1)'）;holdoff1.4（3）k1=-4-2:-1-2;f1=2*k1;k2=-4-2:-1-2;f2=[4444];k3=0-2:4-2; f3=[44444];k4=0-2:4-2; f4=[00000];k5=-8-2:-5-2;f5=0*k5;k6=5-2:8-2; f6=0*k6;holdonstem(k5,f5);[f,k]=lsxj(2*f1,2*f2,k1,k2);[f,k]=lsxj(2*f3,2*f4,k3,k4);stem(k6,f6);title('1.4(2)');holdoff1.4（4）k1=12:42;f1=2*k1;k2=12:42;f2=[4444];k3=-42:02; f3=[44444];k4=-42:02; f4=[00000];k5=52:82;f5=0*k5;k6=-82:-52; f6=0*k6;holdonstem(k5,f5);[f,k]=lsxj(f1,f2,k1,k2);[f,k]=lsxj(f3,f4,k3,k4);stem(k6,f6);title('1.4(4)');holdoff1.11k=-20:20;u=[ones(1,41)];a=[zeros(1,20),1,zeros(1,20)];b=[zeros(1,16),1,zeros(1,24)];h1=a-b;n=-20:20;a=0.8;c=[(a.^n)];h2=u.*c;y1=conv(h1,u);y=conv(h1,h2);stem(y);