clear x
n=0:1:12;
x(n+1)=0;
x(6)=1;
x(9)=-2;
x(12)=6;
figure(1)
stem(n,x,'linewidth',2)
xlabel('n');
ylabel('x(n)');

clear x
n=0:1:15;
x(n+1)=0;
for m=0:15
    if (m < 3)
        x(m+1) = 0;
    elseif (m >=3 && m < 8)
        x(m+1)  = 1;
    elseif (m >= 8 && m < 12)
        x(m+1) = -1;
    end
end
figure(2)
stem(n,x,'linewidth',2)
xlabel('n');
ylabel('x(n)');

clear x
n=0:1:20;
x(n+1)=n;
figure(3)
stem(n,x,'linewidth',2)
xlabel('n');
ylabel('x(n)');

clear x
n=0:1:10;
x(1)=0;
for m=1:10
    x(m+1)=m*m;
end
figure(4)
stem(n,x,'linewidth',2)
xlabel('n');
ylabel('x(n)');

clear x
n=0:1:30;
for m=0:30
    x(m+1)=3*(m-3)*(m-3)*exp(-0.3*m)*sin(2*m/3);
end
figure(5)
stem(n,x,'linewidth',2)
xlabel('n');
ylabel('x(n)');