new file mode 100644
--- /dev/null
+++ b/src/inv.cc
@@ -0,0 +1,130 @@
+// tc-inv.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"
+#include "error.h"
+
+#ifdef WITH_DLD
+tree_constant *
+builtin_inv (tree_constant *args, int nargin, int nargout)
+{
+  tree_constant *retval = new tree_constant [2];
+  retval[0] = inverse (args[1]);
+  return retval;
+}
+#endif
+
+tree_constant
+inverse (tree_constant& a)
+{
+  tree_constant retval;
+
+  tree_constant tmp = a.make_numeric ();
+
+  int nr = tmp.rows ();
+  int nc = tmp.columns ();
+  if (nr == 0 || nc == 0)
+    {
+      int flag = user_pref.propagate_empty_matrices;
+      if (flag < 0)
+	gripe_empty_arg ("inverse", 0);
+      else if (flag == 0)
+	gripe_empty_arg ("inverse", 1);
+    }
+
+  Matrix mtmp;
+  if (nr == 0 && nc == 0)
+    return tree_constant (mtmp);
+
+  switch (tmp.const_type ())
+    {
+    case tree_constant_rep::matrix_constant:
+      {
+	Matrix m = tmp.matrix_value ();
+	if (m.rows () == m.columns ())
+	  {
+	    int info;
+	    double rcond = 0.0;
+	    Matrix minv = m.inverse (info, rcond);
+	    if (info == -1)
+	      message ("inverse",
+		       "matrix singular to machine precision, rcond = %g",
+		       rcond);
+	    else
+	      retval = tree_constant (minv);
+	  }
+	else
+	  gripe_square_matrix_required ("inverse");
+      }
+      break;
+    case tree_constant_rep::scalar_constant:
+      {
+	double d = 1.0 / tmp.double_value ();
+	retval = tree_constant (d);
+      }
+      break;
+    case tree_constant_rep::complex_matrix_constant:
+      {
+	ComplexMatrix m = tmp.complex_matrix_value ();
+	if (m.rows () == m.columns ())
+	  {
+	    int info;
+	    double rcond = 0.0;
+	    ComplexMatrix minv = m.inverse (info, rcond);
+	    if (info == -1)
+	      message ("inverse",
+		       "matrix singular to machine precision, rcond = %g",
+		       rcond);
+	    else
+	      retval = tree_constant (minv);
+	  }
+	else
+	  gripe_square_matrix_required ("inverse");
+      }
+      break;
+    case tree_constant_rep::complex_scalar_constant:
+      {
+	Complex c = 1.0 / tmp.complex_value ();
+	retval = tree_constant (c);
+      }
+      break;
+    default:
+      break;
+    }
+  return retval;
+}
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; page-delimiter: "^/\\*" ***
+;;; End: ***
+*/