new file mode 100644
--- /dev/null
+++ b/src/schur.cc
@@ -0,0 +1,180 @@
+// tc-schur.cc                                           -*- C++ -*-
+/*
+
+Copyright (C) 1993 John W. Eaton
+
+This file is part of Octave.
+
+Octave is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+Octave is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, write to the Free
+Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifdef __GNUG__
+#pragma implementation
+#endif
+
+#include "Matrix.h"
+
+#include "tree-const.h"
+#include "user-prefs.h"
+#include "error.h"
+#include "gripes.h"
+
+#ifdef WITH_DLD
+tree_constant *
+builtin_schur_2 (tree_constant *args, int nargin, int nargout)
+{
+  return schur (args, nargin, nargout);
+}
+#endif
+
+tree_constant *
+schur (tree_constant *args, int nargin, int nargout)
+{
+  tree_constant *retval = NULL_TREE_CONST;
+
+  tree_constant arg = args[1].make_numeric ();
+
+  char *ord;
+  if (nargin != 3)
+    ord = "U";
+  else
+    ord = args[2].string_value ();
+
+  if (*ord != 'U' && *ord != 'A' && *ord != 'D'
+      && *ord != 'u' && *ord != 'a' && *ord != 'd')
+    {
+      warning ("schur: incorrect ordered schur argument `%c'", *ord);
+      Matrix m;
+      retval = new tree_constant [3];
+      retval[0] = tree_constant (m);
+      retval[1] = tree_constant (m);
+      return retval;
+    }
+  int a_nr = arg.rows ();
+  int a_nc = arg.columns ();
+
+  if (a_nr == 0 || a_nc == 0)
+    {
+      int flag = user_pref.propagate_empty_matrices;
+      if (flag != 0)
+        {
+          if (flag < 0)
+            warning ("schur: argument is empty matrix");
+          Matrix m;
+          retval = new tree_constant [3];
+          retval[0] = tree_constant (m);
+          retval[1] = tree_constant (m);
+        }
+      else
+        error ("schur: empty matrix is invalid as argument");
+
+      return retval;
+    }
+  if (a_nr != a_nc)
+    {
+      gripe_square_matrix_required ("schur");
+      return retval;
+    }
+
+  Matrix tmp;
+  ComplexMatrix ctmp;
+ 
+  switch (arg.const_type ())
+    {
+    case tree_constant_rep::matrix_constant:
+      {
+	tmp = arg.matrix_value ();
+
+	SCHUR result (tmp,ord);
+
+        if (nargout == 1)
+          {
+            retval = new tree_constant [2];
+            retval[0] = tree_constant (result.schur_matrix ());
+          }
+        else
+          {
+            retval = new tree_constant [3];
+            retval[0] = tree_constant (result.unitary_matrix ());
+            retval[1] = tree_constant (result.schur_matrix ());
+          }
+      }
+      break;
+    case tree_constant_rep::complex_matrix_constant:
+      {
+	ctmp = arg.complex_matrix_value ();
+
+        ComplexSCHUR result (ctmp,ord);
+ 
+        if (nargout == 1)
+          {
+            retval = new tree_constant [2];
+            retval[0] = tree_constant (result.schur_matrix ());
+          }
+        else
+          {
+            retval = new tree_constant [3];
+            retval[0] = tree_constant (result.unitary_matrix ());
+            retval[1] = tree_constant (result.schur_matrix ());
+          }
+      }    
+      break;
+    case tree_constant_rep::scalar_constant:
+      {
+        double d = arg.double_value ();
+        if (nargout == 1)
+  	  {
+	    retval = new tree_constant [2];
+            retval[0] = tree_constant (d);
+          }
+        else
+	  {
+	    retval = new tree_constant [3];
+	    retval[0] = tree_constant (1);
+	    retval[1] = tree_constant (d);
+  	  }
+      }
+      break;
+    case tree_constant_rep::complex_scalar_constant:
+      {
+        Complex c = arg.complex_value ();
+	if (nargout == 1)
+	  {
+	    retval = new tree_constant [2];
+	    retval[0] = tree_constant (c);
+	  }
+	else
+	  {
+	    retval = new tree_constant [3];
+	    retval[0] = tree_constant (1);
+	    retval[1] = tree_constant (c);
+	  }
+      }
+      break;
+    default:
+      panic_impossible ();
+      break;    
+    }
+ 
+  return retval; 
+}
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; page-delimiter: "^/\\*" ***
+;;; End: ***
+*/