function[C,B,A]=sdir2cas(b,a);
Na=length(a)-1;Nb=length(b)-1;
b0=b(1);b=b/b0;
a0=a(1);a=a/a0;
C=b0/a0;
p=cplxpair(roots(a));k=floor(Na/2);
if k*2==Na
    A=zeros(k,3);
    for n=1:2:Na
        Arow=p(n:1:n+1,:);Arow=poly(Arow);
        A(fix((n+1)/2),:)=real(Arow);
    end
elseif Na==1
    A=[0 real(poly(Arow))];
else
    A=zeros(k+1,3);
   for n=1:2:2*k
        Arow=p(n:1:n+1,:);Arow=poly(Arow);
        A(fix((n+1)/2),:)=real(Arow);
    end 
      A(k+1,:)=[0 real(poly(p(Na)))];
end
z=cplxpair(roots(b));k=floor(Nb/2);
if Nb==0
    B=[0 0 poly(z)];
elseif k*2==Nb
    B=zeros(k,3);
     for n=1:2:Nb
        Brow=z(n:1:n+1,:);Brow=poly(Brow);
        B(fix((n+1)/2),:)=real(Brow);
     end
elseif Nb==1
    A=[0 real(poly(z))];
else 
    B=zeros(k+1,3);
     for n=1:2:2*k
        Brow=z(n:1:n+1,:);Brow=poly(Brow);
        B(fix((n+1)/2),:)=real(Brow);
     end 
       B(k+1,:)=[0 real(poly(z(Nb)))];
end