《DSP using MATLAB》Problem 4.18

代码：

%% ------------------------------------------------------------------------
%%            Output Info about this m-file
fprintf('\n***********************************************************\n');
fprintf('        <DSP using MATLAB> Problem 4.18 \n\n');

banner();
%% ------------------------------------------------------------------------


% ---------------------------------------
%       1   H1(z)
% ---------------------------------------

b = 1/4*[1, 2, 0, 1]; a = [1];               %  

[R, p, C] = residuez(b,a)

Mp = (abs(p))'
Ap = (angle(p))'/pi

%% ----------------------------------------------
%%   START a    determine H(z) and sketch    
%% ----------------------------------------------
figure('NumberTitle', 'off', 'Name', 'P4.18.1 H(z) its pole-zero plot')
set(gcf,'Color','white'); 
zplane(b,a);
title('pole-zero plot'); grid on;

%% ----------------------------------------------
%%    END
%% ----------------------------------------------


% ------------------------------------
%               y1(n)  Output
% ------------------------------------
yb1 = conv(b, [2]);
ya1 = conv(a, [1,-0.9]);

[R1, p1, C1] = residuez(yb1, ya1)

Mp = (abs(p1))'
Ap = (angle(p1))'/pi

[delta, n] = impseq(0, 0, 7); 
y1_check = filter(yb1, ya1, delta)                                             % check sequence

y1_answer = -1.7970*impseq(0,0,7) - 0.6173*impseq(1,0,7) - 0.5556*impseq(2,0,7) + 2.2970*(0.9).^n .* stepseq(0,0,7)         % answer sequence

　　运行结果：

      只做第1小题了，后面的多少有些出入之处，以后有机会补上。