fg_04_03.m

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

% fg_04_03
% Chapter 4, fig. 4.3. z-plane & ampl. gain plots.
b=[1,1]; a=[1,-.9];
sp_fig(1,10,5);
subplot(1,2,1);
pz_plot(b,a);
ejw=exp(j*pi/3);
arrow(-1,0,real(ejw),imag(ejw));
arrow(.9,0,real(ejw),imag(ejw));
h1=text(-.5,.46,'\alpha=|e^{j\omegaT}+1|','rotation',30);
h2=text(.45,.75,'\beta=|e^{j\omegaT}-0.9|','rotation',-65.2);
h3=text(.54,.95,'e^{j\omegaT}','rotation',0);
h4=text(real(ejw)-.03,imag(ejw)+.01,'\bullet');
set([h1,h2,h3],'fontsize',16);
% Ampl. gain.
f=linspace(0,.5,20);
amp=abs(gain_f(b,a,f));
axes('position',[.6 .2 .3 .6]);
axis([0,.5,0,20]);
set(gca,'fontsize',16);
line(f,amp,'color','k'); grid;
xlabel('Frequency {\nu}=\omegaT/2\pi (Hz-s)');
ylabel('|{\itH}(e^{j\omega})|=\alpha/\beta');