function [R,P,K]=pfrac(num,den)
[R,P,K]=residue(num,den); 
for i=1:length(R),
   if imag(P(i))>eps
      a=real(R(i)); b=imag(R(i));
      R(i)=-2*sqrt(a^2+b^2); 
      R(i+1)=atan2(-a,b);
   end
end