--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@pz/ri2fq.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,26 @@
+% 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