% RI2FQ Convert comlpex pole/zero into frequency/Q pole/zero representation.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% DESCRIPTION: RI2FQ Convert comlpex pole/zero into frequency/Q pole/zero
%              representation.
%
% CALL:        [f0, q]= ri2fq(c)
%
% VERSION:     $Id: ri2fq.m,v 1.4 2011/02/18 16:48:54 ingo Exp $
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function [f0, q]= ri2fq(c)

  if(nargin==0)
    disp('usage: [f0, q]= ri2fq(c)');
    return
  end

  a = real(c(1));
  b = imag(c(1));

  f0 = sqrt(a^2 + b^2)/(2*pi);
  q = 0.5*sqrt(1 + b^2/a^2);

end
