%% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%%            Output Info about this m-file

fprintf('\n***********************************************************\n');

fprintf('        <DSP using MATLAB> Problem 6.7 \n\n');

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('\nDirect form: \n');

b = conv(b11, a3) + conv(b3, a11)

a = conv(a11, a3)

fprintf('\nConvert DIRECT-form to PARALLEL-form :     \n');

[C, Bp, Ap] = dir2par(b, a)

fprintf('\nConvert DIRECT-form to CASCADE-form :     \n');

[b0, Bc, Ac] = dir2cas(b, a) 

fprintf('\nConvert TF-form to SOS-form :     \n');

[sos, g] = tf2sos(b, a)

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', 'P6.7 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;