fg_02_06.m

英文书《Digital Signal Processing with Examples in MATLAB》附带的MATLAB实例

% fg_02_06     Chapter 2, Fig. 2.6.
N=50;
n=[0:N-1];
X=[zeros(1,28),ones(1,12),zeros(1,N-40)];
MM=[1 2 3 4 5 6];
sp_fig(1);
for nfig=[1 2 3 4 5 6];
   M=MM(nfig);
   m=[0:M-1];
   % a and b coefficients. Note: b0=0 and a0/2 replaces a0.
   a=(2/N)*X*cos(2*pi*(n')*m/N);
   a(1)=a(1)/2;
   b=(2/N)*X*sin(2*pi*(n')*m/N);
   Xhat=a*cos(2*pi*(m')*n/N)+b*sin(2*pi*(m')*n/N);
%
   subplot(3,2,nfig);
   axis([0 50 -.5 1.5]);
   set(gca,'fontsize',14);
%
   line(n,X,'linestyle','-','Marker','x','color','k'); grid on;
   line(n,Xhat,'linestyle','none','Marker','o','color','r');
   text(7,1.3,['M=',int2str(M)],'fontsize',14);
	if nfig>4,
		xlabel('Sample number');
	end
end