10.80.60.40.20-0.2-0.4-0.6-0.8-1-2-1.5-1-0.500.511.52
五
（1） x[k]=delta[k] k=-50:50;
>> delta=[zeros(1,50),1,zeros(1,50)]; >> stem(k,delta)
10.90.80.70.60.50.40.30.20.10-50-40-30-20-1001020304050
（2） x[k]=u[k] >> k=-50:50;
uk=[zeros(1,50),ones(1,51)]; stem(k,uk)
10.90.80.70.60.50.40.30.20.10-50-40-30-20-1001020304050
(3) k=-50:50;
>> xk=10*(0.5.^k).*[zeros(1,50),ones(1,51)]; >> stem(k,xk)
109876543210-50-40-30-20-1001020304050
(4) k=-50:50;
>> xk=[zeros(1,48),ones(1,7),zeros(1,46)]; >> stem(k,xk)
10.90.80.70.60.50.40.30.20.10-50-40-30-20-1001020304050
(5) k=-50:50;
uk=k.*[zeros(1,50),ones(1,51)]; stem(k,uk)
50454035302520151050-50-40-30-20-1001020304050
(6)
k=-50:50;
>> xk=5.*(0.8.^k).*cos(0.9*pi.*k).*[ones(1,101)]; >> stem(k,xk)
3x 105210-1-2-3-4-50-40-30-20-1001020304050
M2-6 W=0.1pi k=-50:50; >> w=0.1*pi; >> xk=sin(w.*k); >> stem(k,xk);