dir2cas.m

Matlab环境下带控制面板的低通、高通滤波器设计

function [b0,B,A]=dir2cas(b,a);
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
      N=M;
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