dir2cas.m

the file contain many matlab signal source code and many example .

function [b0,B,A]=dir2cas(b,a);
% DIRECT - form to CASCADE - form conversion(cplxpair version)
% ------------------------------------
% [b0,B,A]=dir2cas(b,a)
% b0=gain coefficient
% B=K by 3 matrix of real coefficients containing bk's
% A=K by 3 matrix of real coefficients containing ak's
% b=numberator polynomial coefficients of DIRECT form
% a=denominator polynomial coefficients of DIRECT form
 
% compute gain coefficient b0
b0=b(1);b=b/b0;
a0=a(1);a=a/a0;
b0=b0/a0;
%
M=length(b);N=length(a);
if N>M
    b=[b zeros(1,N-M)];
elseif M>N
    a=[a zeros(1,M-N)];N=M;
else
    NM=0;
end
%
K=floor(N/2);B=zeros(K,3);A=zeros(K,3);
if K*2==N;
    b=[b 0];
    a=[a 0];
end
%
broots=cplxpair(roots(b));
aroots=cplxpair(roots(a));
for i=1:2:2*K
    Brow=broots(i:1:i+1,:);
    Brow=real(poly(Brow));
    B(fix(i+1)/2,:)=Brow;
    Arow=aroots(i:1:i+1,:);
    Arow=real(poly(Arow));
    A(fix(i+1)/2,:)=Arow;
end