--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@pzmodel/fromRational.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,104 @@
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% FUNCTION:    fromRational
+%
+% DESCRIPTION: Construct a pzmodel from a rational TF
+%
+% CALL:        pzm = fromRational(a, pl)
+%
+% PARAMETER:   pl   - plist
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+function pzm = fromRational(pzm, pli)
+  
+  VERSION = '$Id: fromRational.m,v 1.12 2011/08/15 12:20:52 hewitson Exp $';
+  
+  
+  % get pzmodel info
+  ii = pzmodel.getInfo('pzmodel', 'From Rational');
+  
+  % Set the method version string in the minfo object
+  ii.setMversion([VERSION '-->' ii.mversion]);
+  
+  % Combine input plist with default values
+  pl = applyDefaults(ii.plists, pli);
+  
+  % Set fields
+  rat      = find(pl, 'rational');
+  
+  poles = roots(rat.den);
+  zeros = roots(rat.num);
+  
+  % remove conjugate pairs
+  if isempty(poles)
+    ps = [];
+  else
+    ps = {poles(1)};
+    for jj=2:numel(poles)
+      if ~isreal(poles(jj))
+        if~any(conj(poles(jj))==[ps{:}])
+          ps = [ps poles(jj)];
+        end
+      else
+        ps = [ps poles(jj)];
+      end
+    end
+  end
+  
+  if isempty(zeros)
+    zs = [];
+  else
+    zs = {zeros(1)};
+    for jj=2:numel(zeros)
+      if ~isreal(zeros(jj))
+        if~any(conj(zeros(jj))==[zs{:}])
+          zs = [zs zeros(jj)];
+        end
+      else
+        zs = [zs zeros(jj)];
+      end
+    end
+  end
+  
+  % get gain - must be a nicer way, but...
+  ig = abs(resp(rat, plist('f', 0)));
+  
+  % divide for (-2*pi) only when a real pole or zero is found
+  if ~isempty(ps)
+    numps = cell2mat(ps);
+    numps(imag(numps)==0) = numps(imag(numps)==0)/(-2*pi);
+    ps = num2cell(numps);
+  end
+  if ~isempty(zs)
+    numzs = cell2mat(zs);
+    numzs(imag(numzs)==0) = numzs(imag(numzs)==0)/(-2*pi);
+    zs = num2cell(numzs);
+  end
+  
+  % convert to pzmodel
+  pzm = pzmodel(ig.data.getY, ps, zs);
+  
+  % Override some plist values using the input object
+  if isempty(pl.find('ounits'))
+    pl.pset('ounits', rat.ounits);
+  end
+  
+  if isempty(pl.find('iunits'))
+    pl.pset('iunits', rat.iunits);
+  end
+  
+  if isempty(pl.find('name'))
+    pl.pset('name', sprintf('pzmodel(%s)', rat.name));
+  end
+  
+  if isempty(pl.find('description'))
+    pl.pset('description', rat.description);
+  end
+  
+  % Add history
+  pzm.addHistory(ii, pl, [], rat.hist);
+  
+  % Set object properties
+  pzm.setObjectProperties(pl);
+  
+end