dir2par.m

数字信号分析处理方面的好教材,有DSP的MATLAB源程序.

function [C,B,A] = dir2par(b,a);
% DIRECT-form to PARALLEL-form conversion
% --------------------------------------
% [C,B,A] = dir2par(b,a)
%  C = Polynomial part when length(b) >= length(a)
%  B = K by 2 matrix of real coefficients containing bk's
%  A = K by 3 matrix of real coefficients containing ak's
%  b = numerator polynomial coefficients of DIRECT form
%  a = denominator polynomial coefficients of DIRECT form
%

M = length(b); N = length(a);

[r1,p1,C] = residuez(b,a);
p = cplxpair(p1,10000000*eps);
I = cplxcomp(p1,p);
r = r1(I);

K = floor(N/2); B = zeros(K,2); A = zeros(K,3);
if K*2 == N; %N even, order of A(z) odd, one factor is first order
        for i=1:2:N-2
                Brow = r(i:1:i+1,:);
                Arow = p(i:1:i+1,:);
                [Brow,Arow] = residuez(Brow,Arow,[]);
                B(fix((i+1)/2),:) = real(Brow);
                A(fix((i+1)/2),:) = real(Arow);
        end
        [Brow,Arow] = residuez(r(N-1),p(N-1),[]);
        B(K,:) = [real(Brow) 0]; A(K,:) = [real(Arow) 0];
else
        for i=1:2:N-1
                Brow = r(i:1:i+1,:);
                Arow = p(i:1:i+1,:);
                [Brow,Arow] = residuez(Brow,Arow,[]);
                B(fix((i+1)/2),:) = real(Brow);
                A(fix((i+1)/2),:) = real(Arow);
        end
end