《DSP using MATLAB》Problem 6.6

代码：

%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%%            Output Info about this m-file
fprintf('\n***********************************************************\n');
fprintf('        <DSP using MATLAB> Problem 6.6 \n\n');

banner();
%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

hb = [1 cos(0.1*pi) cos(0.2*pi) cos(0.3*pi) cos(0.4*pi)];   % numerator polynominal
ha = [1 0.8*sin(0.1*pi) (0.8^2)*sin(0.2*pi) (0.8^3)*sin(0.3*pi) (0.8^4)*sin(0.4*pi) (0.8^5)*sin(0.5*pi)];

xb = 1;
xa = [1 0 -1];

fprintf('\n FIR filter DIRECT-form:     \n');
b = hb
a = conv(ha, xa)
%a = ha;

fprintf('\nConvert DIRECT-form to CASCADE-form :     \n');
[b0, Bc, Ac] = dir2cas(b, a)

fprintf('\nConvert DIRECT-form to PARALLEL-form :     \n');
[C, Bp, Ap] = dir2par(b, a) 
C = 0;

fprintf('\nConvert DIRECT-form to LATTICE-LADDER-form :     \n');
[Klr, Clr] = dir2ladr(b, a) 

fprintf('\nConvert DIRECT-form to MATLAB LATTICE-LADDER-form :     \n');
[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', 'P6.6 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', 'P6.6 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