% MATLAB script for Illustrative Problem 6.7.
clear
echo on
N=31;
T=1;
alpha=1/4;
n=-(N-1)/2:(N-1)/2;			% the indices for g_T
% The expression for g_T is obtained next.
for i=1:length(n),
  g_T(i)=0;
  for m=-(N-1)/2:(N-1)/2,
    g_T(i)=g_T(i)+sqrt(xrc(4*m/(N*T),alpha,T))*exp(j*2*pi*m*n(i)/N);
    echo off ;
  end;
end;
echo on ;
g_T=real(g_T) ; % The imaginary part is due to the finite machine precision
% Derive g_T(n-(N-1)/2).
n2=0:N-1;
% Get the frequency response characteristics.
[G_T,W]=freqz(g_T,1);
% normalized magnitude response
magG_T_in_dB=20*log10(abs(G_T)/max(abs(G_T)));  	
% impulse response of the cascade of the transmitter and the receiver filters
g_R=g_T;
imp_resp_of_cascade=conv(g_R,g_T);
% Plotting commands follow.