%% wave1dsymfreqdemo
%% show 1D pure wave forms as a function of frequency (positive and negativve)
 
%define sample rates and frequency

N = 32
tN = (0:(N-1))/N;  % discrete time points
K = N/2;  % number of displays
i = sqrt(-1);

% display results 
for k = 0:K
   sampwave = exp(2*pi*i*k*tN);
   
   subplot(3,1,1);
    plot([-N/2,N/2],[0,0],'k', [k,k],[0,0.5],'b', k,0.5,'ob',[-k,-k],[0,-0.5],'b',-k,-0.5,'ob');
    axis([-(N+1)/2,(N+1)/2,-1.1,1.1]);
    title('frequency');
    drawnow

   subplot(3,2,3);
    plot(tN,real(sampwave),'r');
    axis([-0.1,1.1,-1.1,1.1]);
    title('real part');
    drawnow
    
   subplot(3,2,5);
    plot(tN,-imag(sampwave),'g');
    axis([-0.1,1.1,-1.1,1.1]);
    title('imaginary part')
    drawnow
    
   subplot(3,2,4);  
    plot(tN,real(sampwave),'r');
    axis([-0.1,1.1,-1.1,1.1]);
    title('real part');
    drawnow
    
   subplot(3,2,6);
    plot(tN,imag(sampwave),'g');
    axis([-0.1,1.1,-1.1,1.1]);
    title('imaginary part')
    drawnow
    
   disp(['k=',num2str(k),', press a key'])
    
   pause
   end