--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@matrix/det.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,128 @@
+% DET evaluates the determinant for matrix object.
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: DET evaluates the determinant for matrix objects.
+%              The objects must belong to the same class (e.g. ao, smodel, ...)
+%              The result is an object of the class itself
+%
+% CALL:        obj = det(mat)
+%              obj = mat.det()
+%
+% <a href="matlab:utils.helper.displayMethodInfo('matrix', 'det')">Parameters Description</a>
+%
+% VERSION:     $Id: det.m,v 1.13 2011/04/08 08:56:31 hewitson Exp $
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+function out = det(varargin)
+  
+  callerIsMethod = utils.helper.callerIsMethod;
+  
+  if callerIsMethod
+    as = [varargin{:}];
+  else    
+    % Check if this is a call for parameters
+    if utils.helper.isinfocall(varargin{:})
+      out = getInfo(varargin{3});
+      return
+    end
+    
+    % Collect input variable names
+    in_names = cell(size(varargin));
+    for ii = 1:nargin,in_names{ii} = inputname(ii);end
+    
+    % Collect all matrices and plists
+    [as, matrix_invars, rest] = utils.helper.collect_objects(varargin(:), 'matrix', in_names);
+    [pl, pl_invars, rest]     = utils.helper.collect_objects(varargin(:), 'plist', in_names);
+    
+    % Combine input plists and default plist
+    usepl = parse(pl, getDefaultPlist());
+  end
+  
+  % extract objects
+  objmat = as.objs;
+  
+  % we check now the dimensionality to be sure to have a square matrix
+  [rw, cl] = size(objmat);
+  if rw ~= cl
+    error('### Matrix must be square');
+  end
+
+  % Let's go with textbook definition
+  switch cl
+    case 0
+      % To be compliant with definition. 
+      % Here we choose to output an ao, so we can have history; 
+      % if used with other objetcs (ao, smodel, ...) it will be promoted anyways
+      out = ao(1);
+    case 1
+      out = objmat;
+    case 2
+      out = objmat(1,1) .* objmat(2,2) - objmat(2,1) .* objmat(1,2);
+    otherwise
+      dmod_minor = eval(sprintf('%s.initObjectWithSize(1,cl);', class(objmat)));
+      
+      % Cache these objects not to produce them iteratively
+      coeff_minus = ao(-1);
+      coeff_plus = ao(1);
+      for jj = 1:cl
+        Amod = objmat;
+        Amod(1,:) = [];
+        Amod(:,jj) = [];
+        Am = matrix(Amod);
+        if (-1).^(jj+1) > 0
+          coeff = coeff_plus;
+        else
+          coeff = coeff_minus;
+        end
+        dmod_minor(jj) = objmat(1,jj) .* det(Am) * coeff;
+      end
+      % sum over elements
+      out = dmod_minor(1);
+      for kk = 2:numel(dmod_minor)
+        out = out + dmod_minor(kk);
+      end
+  end
+
+  if ~callerIsMethod
+    % Set name
+    out.setName(sprintf('det(%s)', in_names{1}));
+    
+    % Add history
+    out.addHistory(getInfo('None'), usepl, {inputname(1)}, [as(:).hist]);
+  end
+  
+end
+
+%--------------------------------------------------------------------------
+% 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, 'matrix', 'ltpda', utils.const.categories.op, '$Id: det.m,v 1.13 2011/04/08 08:56:31 hewitson Exp $', sets, pl);
+end
+
+%--------------------------------------------------------------------------
+% Get Default Plist
+%--------------------------------------------------------------------------
+
+function plout = getDefaultPlist()
+  persistent pl;
+  if ~exist('pl', 'var') || isempty(pl)
+    pl = buildplist();
+  end
+  plout = pl;
+end
+
+function pl = buildplist()
+  pl = plist.EMPTY_PLIST;
+end
+