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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2008-2025 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// 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
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
#if ! defined (octave_PermMatrix_h)
#define octave_PermMatrix_h 1
#include "octave-config.h"
#include "Array.h"
#include "mx-defs.h"
// Array<T> is inherited privately so that some methods, like index, don't
// produce unexpected results.
class OCTAVE_API PermMatrix : protected Array<octave_idx_type>
{
public:
PermMatrix () = default;
PermMatrix (const PermMatrix& m) = default;
PermMatrix& operator = (const PermMatrix& m) = default;
~PermMatrix () = default;
OCTAVE_API PermMatrix (octave_idx_type n);
OCTAVE_API PermMatrix (const Array<octave_idx_type>& p, bool colp,
bool check = true);
OCTAVE_API PermMatrix (const octave::idx_vector& idx, bool colp,
octave_idx_type n = 0);
octave_idx_type dim1 () const
{ return Array<octave_idx_type>::numel (); }
octave_idx_type dim2 () const
{ return Array<octave_idx_type>::numel (); }
octave_idx_type rows () const { return dim1 (); }
octave_idx_type cols () const { return dim2 (); }
octave_idx_type columns () const { return dim2 (); }
octave_idx_type perm_length () const
{ return Array<octave_idx_type>::numel (); }
// FIXME: a dangerous ambiguity?
octave_idx_type length () const
{ return perm_length (); }
octave_idx_type numel () const { return dim1 () * dim2 (); }
std::size_t byte_size () const
{ return Array<octave_idx_type>::byte_size (); }
dim_vector dims () const { return dim_vector (dim1 (), dim2 ()); }
bool isempty () const { return numel () == 0; }
int ndims () const { return 2; }
const Array<octave_idx_type>& col_perm_vec () const
{ return *this; }
octave_idx_type
elem (octave_idx_type i, octave_idx_type j) const
{
return (Array<octave_idx_type>::elem (j) == i) ? 1 : 0;
}
octave_idx_type
checkelem (octave_idx_type i, octave_idx_type j) const;
octave_idx_type
operator () (octave_idx_type i, octave_idx_type j) const
{
return elem (i, j);
}
// These are, in fact, super-fast.
OCTAVE_API PermMatrix transpose () const;
OCTAVE_API PermMatrix inverse () const;
// Determinant, i.e., the sign of permutation.
OCTAVE_API octave_idx_type determinant () const;
// Efficient integer power of a permutation.
OCTAVE_API PermMatrix power (octave_idx_type n) const;
bool is_col_perm () const { return true; }
bool is_row_perm () const { return false; }
void print_info (std::ostream& os, const std::string& prefix) const
{ Array<octave_idx_type>::print_info (os, prefix); }
static OCTAVE_API PermMatrix eye (octave_idx_type n);
private:
PermMatrix pos_power (octave_idx_type m) const;
void setup (const Array<octave_idx_type>& p, bool colp, bool check);
void setup (const octave::idx_vector& idx, bool colp, octave_idx_type n);
};
// Multiplying permutations together.
OCTAVE_API PermMatrix
operator * (const PermMatrix& a, const PermMatrix& b);
#endif
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