% frequency repsonse for pure exponentials

% set parmeters and signal
N = 128;
k = 8;
t = (0:(N-1))/N;
I = sqrt(-1)
E =  exp(2*pi*I*k*t);


% set filter and convolve
L  = [1,2,3,2,1]/9;
n = size(L,2)
LE = circconv(E,L);

% show signal filter and convolved signal;

figure(1)
subplot(3,1,1)
plot(t,real(E),'r-');
axis([0,1,-1.5,1.5]);
title('real parts of original signal')
subplot(3,1,2)
plot(t,imag(E),'g-');
axis([0,1,-1.5,1.5]);
title('imaginary part of original signal')

subplot(3,1,3)
stem(0:(n-1),L,'filled')
title('filter in stem plot form');

disp('Press a key for filtered wave forms')
pause

subplot(3,1,1)
plot(t,real(E),'r-',t,real(LE),'r-.' );
axis([0,1,-1.5,1.5]);
title('real part of original signal and filetered signal')

subplot(3,1,2)
plot(t,imag(E),'g-',t,imag(LE),'g-.' );
axis([0,1,-1.5,1.5]);
title('imaginary parts of original signal and filetered signal')