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@@ -0,0 +1,154 @@
+// tc-lu.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 "gripes.h"
+
+#ifdef WITH_DLD
+tree_constant *
+builtin_lu_2 (tree_constant *args, int nargin, int nargout)
+{
+  return lu (args[1], nargout);
+}
+#endif
+
+tree_constant *
+lu (tree_constant& a, int nargout)
+{
+  tree_constant *retval = new tree_constant [4];
+
+  tree_constant tmp = a.make_numeric ();;
+    
+  if (tmp.rows () == 0 || tmp.columns () == 0)
+    {
+      int flag = user_pref.propagate_empty_matrices;
+      if (flag != 0)
+	{
+	  if (flag < 0)
+	    gripe_empty_arg ("lu", 0);
+	  Matrix m;
+	  retval = new tree_constant [4];
+	  retval[0] = tree_constant (m);
+	  retval[1] = tree_constant (m);
+	  retval[2] = tree_constant (m);
+	  return retval;
+	}
+      else
+	gripe_empty_arg ("lu", 1);
+    }
+
+  switch (tmp.const_type ())
+    {
+    case tree_constant_rep::matrix_constant:
+      {
+	Matrix m = tmp.matrix_value ();
+	if (m.rows () == m.columns ())
+	  {
+	    LU fact (m);
+	    switch (nargout)
+	      {
+	      case 1:
+	      case 2:
+		{
+		  Matrix P = fact.P ();
+		  Matrix L = P.transpose () * fact.L ();
+		  retval[0] = tree_constant (L);
+		  retval[1] = tree_constant (fact.U ());
+		}
+		break;
+	      case 3:
+	      default:
+		retval[0] = tree_constant (fact.L ());
+		retval[1] = tree_constant (fact.U ());
+		retval[2] = tree_constant (fact.P ());
+		break;
+	      }
+	  }
+	else
+	  gripe_square_matrix_required ("lu");
+      }
+      break;
+    case tree_constant_rep::complex_matrix_constant:
+      {
+	ComplexMatrix m = tmp.complex_matrix_value ();
+	if (m.rows () == m.columns ())
+	  {
+	    ComplexLU fact (m);
+	    switch (nargout)
+	      {
+	      case 1:
+	      case 2:
+		{
+		  ComplexMatrix P = fact.P ();
+		  ComplexMatrix L = P.transpose () * fact.L ();
+		  retval[0] = tree_constant (L);
+		  retval[1] = tree_constant (fact.U ());
+		}
+		break;
+	      case 3:
+	      default:
+		retval[0] = tree_constant (fact.L ());
+		retval[1] = tree_constant (fact.U ());
+		retval[2] = tree_constant (fact.P ());
+		break;
+	      }
+	  }
+	else
+	  gripe_square_matrix_required ("lu");
+      }
+      break;
+    case tree_constant_rep::scalar_constant:
+      {
+	double d = tmp.double_value ();
+	retval[0] = tree_constant (1.0);
+	retval[1] = tree_constant (d);
+	retval[2] = tree_constant (1.0);
+      }
+      break;
+    case tree_constant_rep::complex_scalar_constant:
+      {
+	Complex c = tmp.complex_value ();
+	retval[0] = tree_constant (1.0);
+	retval[1] = tree_constant (c);
+	retval[2] = tree_constant (1.0);
+      }
+      break;
+    default:
+      break;
+    }
+  return retval;
+}
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; page-delimiter: "^/\\*" ***
+;;; End: ***
+*/