%% freqrespplot.m
%% plot filter and frequency reponse 
%% nagmitude and phase

%define sample rate, frequencydomain, and filter
N = 128;
FD = (0:(N-1))-N/2;
L  = [1,1]/2;
n = size(L,2);
Lp = [L,zeros(1,N-n)];

% get dft and frequency domain
fL = fftshift(fft(Lp)); 

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

subplot(3,1,2)
plot(FD,abs(fL),'r')
title('magnitude of filter DFT');
axis tight

subplot(3,1,3)
plot(FD,angle(fL),'r')
title('phase of filter DFT');
axis tight