% Example 3.1
% a)x(n)=2*delta(n+2)-delta(n-4),-5 %
n=[-5:5];
x=2*impseq(-2,-5,5)-impseq(4,-5,5);
subplot(221)
stem(n,x)
title('Sequence in Example 3.1a')
xlabel('n');
ylabel('x(n)');
axis([-5,5,-2,3])
%
% b)x(n)=n[u(n)-u(n-10)]+10*exp(-0.3(n-10))[u(n-10)
% -u(n-20)];0 %
n=[0:20];
x1=n.*(stepseq(0,0,20)-stepseq(10,0,20));
x2=10*exp(-0.3*(n-10)).*(stepseq(10,0,20)-stepseq(20,0,20));
x=x1+x2;
subplot(222);
stem(n,x);
title('Sequence in Example 3.1b')
xlabel('n');
ylabel('x(n)');
axis([0,20,-1,11])
%
% c)x(n)=cos(0.04*pi*n)+0.2*w(n);0 %
n=[0:50];
x=cos(0.04*pi*n)+0.2*randn(size(n));
subplot(223)
stem(n,x)
axis([0,50,-1.4,1.4])
%
% d)x(n)={...,5 4 3 2 1 5 4 3 2 1,...};-10 %
n=[-10:9];
x=[5 4 3 2 1];
xtilde=x'*ones(1,4);
xtilde=(xtilde(:))';
subplot(224)
stem(n,xtilde);
axis([-10,9,-1,6])
