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

%%            Output Info about this m-file

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

fprintf('        <DSP using MATLAB> Problem 6.14 \n\n');

banner();

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

H1_C = 2;

H1_a1 = [1   0.9  0.9]; H1_b1 = [0.2  -0.3];

H1_a2 = [1  -0.8  0.8]; H1_b2 = [0.4   0.5];

H2_a1 = [1   1.7  0.72]; H2_b1 = [2  1  -1];

H2_a2 = [1  -1.5  0.56]; H2_b2 = [3  4   5];

% ------------------------------------------------------

%       1st way to get a and b

% ------------------------------------------------------

H1_a = conv(H1_a1, H1_a2)

H1_b11 = conv(H1_b1, H1_a2) + conv(H1_b2, H1_a1);

H1_b11 = [H1_b11 zeros(length(H1_a)-length(H1_b11))]

H1_b = 2*H1_a + H1_b11

H2_b = conv(H2_b1, H2_b2)

H2_a = conv(H2_a1, H2_a2)

format short;

fprintf('\n1st way to get DIRECT-form:     \n');

a = conv(H1_a, H2_a)

b = conv(H1_b, H2_a) + conv(H2_b, H1_a)

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

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

if size(C)==0

  C = 0;

end

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

% -------------------------------------------

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

[b_c2d, a_c2d] = cas2dir(b0, Bc, Ac) 

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

[b_s2t, a_s2t] = sos2tf(sos, g)