代码：
%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%% Output Info about this m-file
fprintf('
***********************************************************
');
fprintf(' <DSP using MATLAB> Problem 6.7
');
banner();
%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
b1 = [2 0 2]; nb1 = [0:2];
b2 = [2 -1]; nb2 = [0:1];
b3 = [1 2 1]; nb3 = [0:2];
a1 = [1 -0.8 0.64]; na1 = [0:2];
a2 = [1 -0.75]; na2 = [0:1];
a3 = [1 0 0.81]; na3 = [0:2];
a11 = conv(a1, a2); b11 = conv(b1, a2) + conv(b2, a1);
fprintf('
Direct form:
');
b = conv(b11, a3) + conv(b3, a11)
a = conv(a11, a3)
fprintf('
Convert DIRECT-form to PARALLEL-form :
');
[C, Bp, Ap] = dir2par(b, a)
fprintf('
Convert DIRECT-form to CASCADE-form :
');
[b0, Bc, Ac] = dir2cas(b, a)
fprintf('
Convert TF-form to SOS-form :
');
[sos, g] = tf2sos(b, a)
fprintf('
Convert DIRECT-form to LATTICE-LADDER-form :
');
[Klr, Clr] = dir2ladr(b, a)
fprintf('
Convert DIRECT-form to MATLAB LATTICE-LADDER-form :
');
[K, V] = tf2latc(b, a)
% -----------------------------------------
% START check
% -----------------------------------------
n = [0:7];
delta = impseq(0, 0, 7)
%format long
format short
hcas = casfiltr(b0, Bc, Ac, delta)
hpar = parfiltr(C, Bp, Ap, delta)
hladr = ladrfilt(Klr, Clr, delta)
hdir = filter(b, a, delta)
% -------------------------------------------
% END check
% -------------------------------------------
figure('NumberTitle', 'off', 'Name', 'P6.7 hcas(n), hpar(n)')
set(gcf,'Color','white');
subplot(2,1,1); stem(n, hcas);
xlabel('n'); ylabel('hcas(n)');
title('hcas(n)'); grid on;
subplot(2,1,2); stem(n, hpar);
xlabel('n'); ylabel('hpar(n)');
title('hpar(n)'); grid on;
figure('NumberTitle', 'off', 'Name', 'P6.7 hladr(n) hdir(n)')
set(gcf,'Color','white');
subplot(2,1,1); stem(n, hladr);
xlabel('n'); ylabel('hladr(n)');
title('hladr(n)'); grid on;
subplot(2,1,2); stem(n, hdir);
xlabel('n'); ylabel('hdir(n)');
title('hdir(n)'); grid on;
运行结果：
直接形式系数
串联形式系数
并联形式系数
格型系数
