--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@ssm/isStable.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,86 @@
+% ISSTABLE tells if ssm is numerically stable
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: ISSTABLE tells if ssm is numerically stable
+%
+%              val = sys.isStable
+%
+% <a href="matlab:utils.helper.displayMethodInfo('ssm', 'isStable')">Parameters Description</a>
+%
+% VERSION: $Id: isStable.m,v 1.6 2011/04/08 08:56:23 hewitson Exp $
+% 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+function varargout = isStable(varargin)
+  %%% Check if this is a call for parameters
+  if utils.helper.isinfocall(varargin{:})
+    varargout{1} = getInfo(varargin{3});
+    return
+  end
+  objs = utils.helper.collect_objects(varargin(:), 'ssm');
+  
+  utils.helper.msg(utils.const.msg.MNAME, ['running ', mfilename]);
+  
+  for i=1:numel(objs)
+    if ~objs(i).isnumerical  % checking system is numeric
+      error(['error in double : system named ' objs(i).name ' is not numeric']);
+    end
+    A = ssm.blockMatFusion(objs(i).amats, objs(i).sssizes, objs(i).sssizes);
+    Ts = objs(i).timestep;
+    if Ts == 0
+      vp = eig(A);
+      f = find(real(vp)>5e-15);
+      f2 = find(real(vp)>0);
+      display((vp(f)));
+    else
+      try
+        vp = eig(A^1024);
+      catch ME
+        vp = eig(A);
+      end
+      f = find(abs(vp)>1+5e-12);
+      f2 = find(abs(vp)>1);
+      display((vp(f)));
+    end
+    ninst = numel(f);
+    ninst2 = numel(f2);
+    isst(i) = ninst==0;
+    if ninst>0;
+      display(['warning, system named "' objs(i).name '" is not stable'])
+    elseif ninst2>0;
+      display(['warning, system named "' objs(i).name '" might be numerically unstable'])
+    else
+      display(['System named "' objs(i).name '" is stable'])
+    end
+  end
+  varargout ={isst};
+end
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%                               Local Functions                               %
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%--------------------------------------------------------------------------
+% Get Info Object
+%--------------------------------------------------------------------------
+function ii = getInfo(varargin)
+  
+  if nargin == 1 && strcmpi(varargin{1}, 'None')
+    sets = {};
+    pl   = [];
+  else
+    sets = {'Default'};
+    pl   = getDefaultPlist;
+  end
+  % Build info object
+  ii = minfo(mfilename, 'ssm', 'ltpda', utils.const.categories.output, '$Id: isStable.m,v 1.6 2011/04/08 08:56:23 hewitson Exp $', sets, pl);
+end
+
+%--------------------------------------------------------------------------
+% Get Default Plist
+%--------------------------------------------------------------------------
+function pl = getDefaultPlist()
+  pl = plist();
+end
+