clear variables;

N=10;

num = 1;
den=[1 zeros(1,N-1) -1];

%primele 100 de esantioane
h=impz(num,den,100);
figure, stem(0:length(h)-1, h);

%raspunsul in frecventa
figure, freqz(num,den,2^10);

%stabilitate
figure,zplane(num,den);
if(isstable(num,den) == 1)
    disp('Sistem stabil')
else
    disp('Sistemul este instabil')
end

%excitatia
n=0:100;
for i=1:length(n-1)
    if n(i)>=0 && n(i)<=9
        x(i)=9-n(i);
    else 
        x(i)=0;
    end
end
y=conv(x,h);
figure,stem(0:length(y)-1,y);