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+++ b/liboctave/PermMatrix.cc
@@ -0,0 +1,148 @@
+/*
+
+Copyright (C) 2008 Jaroslav Hajek
+
+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 3 of the License, 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, see
+<http://www.gnu.org/licenses/>.
+
+*/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "PermMatrix.h"
+#include "idx-vector.h"
+#include "error.h"
+#include "Array-util.h"
+
+static void
+gripe_invalid_permutation (void)
+{
+  (*current_liboctave_error_handler)
+    ("PermMatrix: invalid permutation vector");
+}
+
+PermMatrix::PermMatrix (const Array<octave_idx_type>& p, bool colp, bool check)
+  : Array<octave_idx_type> (p), _colp(colp)
+{
+  this->dimensions = dim_vector (p.length (), p.length ());
+  if (check)
+    {
+      if (! idx_vector (p).is_permutation (p.length ()))
+        {
+          gripe_invalid_permutation ();
+          Array<octave_idx_type>::operator = (Array<octave_idx_type> ());
+        }
+    }
+}
+
+PermMatrix::PermMatrix (const idx_vector& idx, bool colp, octave_idx_type n)
+  : Array<octave_idx_type> (), _colp(colp)
+{
+  octave_idx_type len = idx.length (n);
+  if (! idx.is_permutation (len))
+    gripe_invalid_permutation ();
+  else
+    {
+      Array<octave_idx_type> idxa (len);
+      for (octave_idx_type i = 0; i < len; i++) idxa(i) = idx(i);
+      Array<octave_idx_type>::operator = (idxa);
+      this->dimensions = dim_vector (len, len);
+    }
+}
+
+PermMatrix::PermMatrix (octave_idx_type n)
+  : Array<octave_idx_type> (n), _colp (false)
+{
+  this->dimensions = dim_vector (n, n);
+  for (octave_idx_type i = 0; i < n; i++) xelem (i) = i;
+}
+
+octave_idx_type 
+PermMatrix::checkelem (octave_idx_type i, octave_idx_type j) const
+{
+  octave_idx_type len = Array<octave_idx_type>::length ();
+  if (i < 0 || j < 0 || i > len || j > len)
+    {
+      (*current_liboctave_error_handler) ("index out of range");
+      return 0;
+    }
+  else
+    return elem (i, j);
+}
+
+
+PermMatrix 
+PermMatrix::transpose (void) const
+{
+  PermMatrix retval (*this);
+  retval._colp = ! retval._colp;
+  return retval;
+}
+
+PermMatrix 
+PermMatrix::inverse (void) const
+{
+  return transpose ();
+}
+
+octave_idx_type 
+PermMatrix::determinant (void) const
+{
+  Array<octave_idx_type> pa = *this;
+  octave_idx_type len = pa.length (), *p = pa.fortran_vec ();
+  bool neg = false;
+  for (octave_idx_type i = 0; i < len; i++)
+    {
+      octave_idx_type j = p[i];
+      if (j != i)
+        {
+          p[i] = p[j];
+          p[j] = j;
+          neg = ! neg;
+        }
+    }
+  
+  return neg ? -1 : 1;
+}
+
+PermMatrix 
+operator *(const PermMatrix& a, const PermMatrix& b)
+{
+  const Array<octave_idx_type>& ia = a, ib = b;
+  PermMatrix r;
+  octave_idx_type n = a.columns ();
+  if (n != b.rows ())
+    gripe_nonconformant ("operator *", n, n, b.rows (), b.rows ());
+  else if (a._colp == b._colp)
+    {
+      r = PermMatrix ((a._colp 
+                       ? ia.index (idx_vector (ib)) 
+                       : ib.index (idx_vector (ia))), a._colp, false);
+    }
+  else
+    {
+      Array<octave_idx_type> ra (n);
+      if (a._colp)
+        ra.assign (idx_vector (ib), ia);
+      else
+        ra.assign (idx_vector (ia), ib);
+      r = PermMatrix (ra, a._colp, false);
+    }
+
+  return r;
+}