Ex4.m

%Exercitiul 4 


%a)
    z=zeros(1, 21);  
for i=6 : 6 :21                                        %in for creeam vectorul din cerinta
z(1,i)=1;
end 

    n= 0:20;
    m= -5:15;
    
figure(1)                                              %astfel vor fi afisate toate graficele 
subplot(2,1,1), stem(n,z,'r*'),title('Ex 4 a'), grid   %afisarea din cerinta
subplot(2,1,2), stem(m,z,'b*'),title('EX 4 a'), grid


% b)
    t= abs(10-n);                                      %creeeam vectorul din cerinta
    
 figure(2)
 stem(n,t,'rd'), title('EX 4 b')
 
 %c
 
    q1= -15:25;
    q2= 0:50;
    
    x1=sin((pi/17)*q1);
    x2=cos((pi/sqrt(23))*q2);

 figure(3)
 plot(q1,x1,q2,x2),grid,title('Ex 4 c sinus si cosinus')
 
 
 figure(4)
 subplot(2,1,1), plot(q1,x1,'r*'),grid,title(' Ex 4 c sinus')
 subplot(2,1,2), plot(q2,x2,'b*'),grid,title('Ex 4 c cosinus')
 
 figure(5)
 subplot(2,1,1), stem(q1,x1,'rd'),grid,title(' Ex 4 c sinus')
 subplot(2,1,2), stem(q2,x2,'bd'),grid,title('Ex 4 c cosinus')