view liboctave/array/dMatrix.cc @ 22204:469c817eb256

svd: reduce code duplication with more use of template and macro. * liboctave/numeric/svd.cc, liboctave/numeric/svd.h: remove unused constructor with reference for int (info). This allows to move all of the constructor into a single template, so remove init(). Two new methods, gesvd and gesdd, are fully specialized but the main hunck of code are the long list of arguments. Scope type and drive enums to the svd class for clarity, and rename member names. Add a new member for the drive used. * libinterp/corefcn/svd.cc: fix typenames for the svd enums which are now scoped. * CMatrix.cc, dMatrix.cc, fCMatrix.cc, fMatrix.cc: fix typenames for the svd enums which are now scoped.
author Carnë Draug <carandraug@octave.org>
date Thu, 04 Aug 2016 20:20:27 +0100
parents e43d83253e28
children 77c4d43e06d1
line wrap: on
line source

// Matrix manipulations.
/*

Copyright (C) 1994-2015 John W. Eaton
Copyright (C) 2008 Jaroslav Hajek
Copyright (C) 2009 VZLU Prague, a.s.

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/>.

*/

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <cfloat>

#include <iostream>
#include <vector>

#include "Array-util.h"
#include "byte-swap.h"
#include "boolMatrix.h"
#include "chMatrix.h"
#include "chol.h"
#include "dMatrix.h"
#include "dDiagMatrix.h"
#include "CMatrix.h"
#include "dColVector.h"
#include "dRowVector.h"
#include "CColVector.h"
#include "PermMatrix.h"
#include "DET.h"
#include "schur.h"
#include "svd.h"
#include "f77-fcn.h"
#include "functor.h"
#include "lo-error.h"
#include "oct-locbuf.h"
#include "lo-ieee.h"
#include "lo-mappers.h"
#include "lo-utils.h"
#include "mx-m-dm.h"
#include "mx-dm-m.h"
#include "mx-inlines.cc"
#include "mx-op-defs.h"
#include "oct-cmplx.h"
#include "oct-fftw.h"
#include "oct-norm.h"
#include "quit.h"

// Fortran functions we call.

extern "C"
{
  F77_RET_T
  F77_FUNC (xilaenv, XILAENV) (const F77_INT&,
                               F77_CONST_CHAR_ARG_DECL,
                               F77_CONST_CHAR_ARG_DECL,
                               const F77_INT&, const F77_INT&,
                               const F77_INT&, const F77_INT&,
                               F77_INT&
                               F77_CHAR_ARG_LEN_DECL
                               F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgebal, DGEBAL) (F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT&,
                             F77_INT&, F77_DBLE*, F77_INT&
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgebak, DGEBAK) (F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_INT&,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgemm, DGEMM) (F77_CONST_CHAR_ARG_DECL,
                           F77_CONST_CHAR_ARG_DECL,
                           const F77_INT&, const F77_INT&,
                           const F77_INT&, const F77_DBLE&,
                           const F77_DBLE*, const F77_INT&,
                           const F77_DBLE*, const F77_INT&,
                           const F77_DBLE&, F77_DBLE*, const F77_INT&
                           F77_CHAR_ARG_LEN_DECL
                           F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgemv, DGEMV) (F77_CONST_CHAR_ARG_DECL,
                           const F77_INT&, const F77_INT&,
                           const F77_DBLE&, const F77_DBLE*,
                           const F77_INT&, const F77_DBLE*,
                           const F77_INT&, const F77_DBLE&, F77_DBLE*,
                           const F77_INT&
                           F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (xddot, XDDOT) (const F77_INT&, const F77_DBLE*,
                           const F77_INT&, const F77_DBLE*,
                           const F77_INT&, F77_DBLE&);

  F77_RET_T
  F77_FUNC (dsyrk, DSYRK) (F77_CONST_CHAR_ARG_DECL,
                           F77_CONST_CHAR_ARG_DECL,
                           const F77_INT&, const F77_INT&,
                           const F77_DBLE&, const F77_DBLE*, const F77_INT&,
                           const F77_DBLE&, F77_DBLE*, const F77_INT&
                           F77_CHAR_ARG_LEN_DECL
                           F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgetrf, DGETRF) (const F77_INT&, const F77_INT&,
                             F77_DBLE*, const F77_INT&,
                             F77_INT*, F77_INT&);

  F77_RET_T
  F77_FUNC (dgetrs, DGETRS) (F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_INT&,
                             const F77_DBLE*, const F77_INT&,
                             const F77_INT*, F77_DBLE*,
                             const F77_INT&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgetri, DGETRI) (const F77_INT&, F77_DBLE*,
                             const F77_INT&, const F77_INT*,
                             F77_DBLE*, const F77_INT&,
                             F77_INT&);

  F77_RET_T
  F77_FUNC (dgecon, DGECON) (F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, const F77_DBLE&, F77_DBLE&,
                             F77_DBLE*, F77_INT*, F77_INT&
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dgelsy, DGELSY) (const F77_INT&, const F77_INT&,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT*,
                             F77_DBLE&, F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT&);

  F77_RET_T
  F77_FUNC (dgelsd, DGELSD) (const F77_INT&, const F77_INT&,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_DBLE*, F77_DBLE&,
                             F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT*,
                             F77_INT&);

  F77_RET_T
  F77_FUNC (dpotrf, DPOTRF) (F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, F77_DBLE *,
                             const F77_INT&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dpocon, DPOCON) (F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, F77_DBLE*,
                             const F77_INT&, const F77_DBLE&,
                             F77_DBLE&, F77_DBLE*, F77_INT*,
                             F77_INT&
                             F77_CHAR_ARG_LEN_DECL);
  F77_RET_T
  F77_FUNC (dpotrs, DPOTRS) (F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_INT&,
                             const F77_DBLE*, const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dtrtri, DTRTRI) (F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_DBLE*,
                             const F77_INT&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL);
  F77_RET_T
  F77_FUNC (dtrcon, DTRCON) (F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_DBLE*,
                             const F77_INT&, F77_DBLE&,
                             F77_DBLE*, F77_INT*, F77_INT&
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL);
  F77_RET_T
  F77_FUNC (dtrtrs, DTRTRS) (F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_INT&,
                             const F77_DBLE*, const F77_INT&, F77_DBLE*,
                             const F77_INT&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (dlartg, DLARTG) (const F77_DBLE&, const F77_DBLE&, F77_DBLE&,
                             F77_DBLE&, F77_DBLE&);

  F77_RET_T
  F77_FUNC (dtrsyl, DTRSYL) (F77_CONST_CHAR_ARG_DECL,
                             F77_CONST_CHAR_ARG_DECL,
                             const F77_INT&, const F77_INT&,
                             const F77_INT&, const F77_DBLE*,
                             const F77_INT&, const F77_DBLE*,
                             const F77_INT&, const F77_DBLE*,
                             const F77_INT&, F77_DBLE&, F77_INT&
                             F77_CHAR_ARG_LEN_DECL
                             F77_CHAR_ARG_LEN_DECL);

  F77_RET_T
  F77_FUNC (xdlange, XDLANGE) (F77_CONST_CHAR_ARG_DECL,
                               const F77_INT&, const F77_INT&,
                               const F77_DBLE*, const F77_INT&,
                               F77_DBLE*, F77_DBLE&
                               F77_CHAR_ARG_LEN_DECL);
}

// Matrix class.

Matrix::Matrix (const RowVector& rv)
  : NDArray (rv)
{
}

Matrix::Matrix (const ColumnVector& cv)
  : NDArray (cv)
{
}

Matrix::Matrix (const DiagMatrix& a)
  : NDArray (a.dims (), 0.0)
{
  for (octave_idx_type i = 0; i < a.length (); i++)
    elem (i, i) = a.elem (i, i);
}

Matrix::Matrix (const MDiagArray2<double>& a)
  : NDArray (a.dims (), 0.0)
{
  for (octave_idx_type i = 0; i < a.length (); i++)
    elem (i, i) = a.elem (i, i);
}

Matrix::Matrix (const DiagArray2<double>& a)
  : NDArray (a.dims (), 0.0)
{
  for (octave_idx_type i = 0; i < a.length (); i++)
    elem (i, i) = a.elem (i, i);
}

Matrix::Matrix (const PermMatrix& a)
  : NDArray (a.dims (), 0.0)
{
  const Array<octave_idx_type> ia (a.col_perm_vec ());
  octave_idx_type len = a.rows ();
  for (octave_idx_type i = 0; i < len; i++)
    elem (ia(i), i) = 1.0;
}

// FIXME: could we use a templated mixed-type copy function here?

Matrix::Matrix (const boolMatrix& a)
  : NDArray (a)
{
}

Matrix::Matrix (const charMatrix& a)
  : NDArray (a.dims ())
{
  for (octave_idx_type i = 0; i < a.rows (); i++)
    for (octave_idx_type j = 0; j < a.cols (); j++)
      elem (i, j) = static_cast<unsigned char> (a.elem (i, j));
}

bool
Matrix::operator == (const Matrix& a) const
{
  if (rows () != a.rows () || cols () != a.cols ())
    return false;

  return mx_inline_equal (numel (), data (), a.data ());
}

bool
Matrix::operator != (const Matrix& a) const
{
  return !(*this == a);
}

bool
Matrix::is_symmetric (void) const
{
  if (is_square () && rows () > 0)
    {
      for (octave_idx_type i = 0; i < rows (); i++)
        for (octave_idx_type j = i+1; j < cols (); j++)
          if (elem (i, j) != elem (j, i))
            return false;

      return true;
    }

  return false;
}

Matrix&
Matrix::insert (const Matrix& a, octave_idx_type r, octave_idx_type c)
{
  Array<double>::insert (a, r, c);
  return *this;
}

Matrix&
Matrix::insert (const RowVector& a, octave_idx_type r, octave_idx_type c)
{
  octave_idx_type a_len = a.numel ();

  if (r < 0 || r >= rows () || c < 0 || c + a_len > cols ())
    (*current_liboctave_error_handler) ("range error for insert");

  if (a_len > 0)
    {
      make_unique ();

      for (octave_idx_type i = 0; i < a_len; i++)
        xelem (r, c+i) = a.elem (i);
    }

  return *this;
}

Matrix&
Matrix::insert (const ColumnVector& a, octave_idx_type r, octave_idx_type c)
{
  octave_idx_type a_len = a.numel ();

  if (r < 0 || r + a_len > rows () || c < 0 || c >= cols ())
    (*current_liboctave_error_handler) ("range error for insert");

  if (a_len > 0)
    {
      make_unique ();

      for (octave_idx_type i = 0; i < a_len; i++)
        xelem (r+i, c) = a.elem (i);
    }

  return *this;
}

Matrix&
Matrix::insert (const DiagMatrix& a, octave_idx_type r, octave_idx_type c)
{
  octave_idx_type a_nr = a.rows ();
  octave_idx_type a_nc = a.cols ();

  if (r < 0 || r + a_nr > rows () || c < 0 || c + a_nc > cols ())
    (*current_liboctave_error_handler) ("range error for insert");

  fill (0.0, r, c, r + a_nr - 1, c + a_nc - 1);

  octave_idx_type a_len = a.length ();

  if (a_len > 0)
    {
      make_unique ();

      for (octave_idx_type i = 0; i < a_len; i++)
        xelem (r+i, c+i) = a.elem (i, i);
    }

  return *this;
}

Matrix&
Matrix::fill (double val)
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr > 0 && nc > 0)
    {
      make_unique ();

      for (octave_idx_type j = 0; j < nc; j++)
        for (octave_idx_type i = 0; i < nr; i++)
          xelem (i, j) = val;
    }

  return *this;
}

Matrix&
Matrix::fill (double val, octave_idx_type r1, octave_idx_type c1,
              octave_idx_type r2, octave_idx_type c2)
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (r1 < 0 || r2 < 0 || c1 < 0 || c2 < 0
      || r1 >= nr || r2 >= nr || c1 >= nc || c2 >= nc)
    (*current_liboctave_error_handler) ("range error for fill");

  if (r1 > r2) { std::swap (r1, r2); }
  if (c1 > c2) { std::swap (c1, c2); }

  if (r2 >= r1 && c2 >= c1)
    {
      make_unique ();

      for (octave_idx_type j = c1; j <= c2; j++)
        for (octave_idx_type i = r1; i <= r2; i++)
          xelem (i, j) = val;
    }

  return *this;
}

Matrix
Matrix::append (const Matrix& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nr != a.rows ())
    (*current_liboctave_error_handler) ("row dimension mismatch for append");

  octave_idx_type nc_insert = nc;
  Matrix retval (nr, nc + a.cols ());
  retval.insert (*this, 0, 0);
  retval.insert (a, 0, nc_insert);
  return retval;
}

Matrix
Matrix::append (const RowVector& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nr != 1)
    (*current_liboctave_error_handler) ("row dimension mismatch for append");

  octave_idx_type nc_insert = nc;
  Matrix retval (nr, nc + a.numel ());
  retval.insert (*this, 0, 0);
  retval.insert (a, 0, nc_insert);
  return retval;
}

Matrix
Matrix::append (const ColumnVector& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nr != a.numel ())
    (*current_liboctave_error_handler) ("row dimension mismatch for append");

  octave_idx_type nc_insert = nc;
  Matrix retval (nr, nc + 1);
  retval.insert (*this, 0, 0);
  retval.insert (a, 0, nc_insert);
  return retval;
}

Matrix
Matrix::append (const DiagMatrix& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nr != a.rows ())
    (*current_liboctave_error_handler) ("row dimension mismatch for append");

  octave_idx_type nc_insert = nc;
  Matrix retval (nr, nc + a.cols ());
  retval.insert (*this, 0, 0);
  retval.insert (a, 0, nc_insert);
  return retval;
}

Matrix
Matrix::stack (const Matrix& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nc != a.cols ())
    (*current_liboctave_error_handler) ("column dimension mismatch for stack");

  octave_idx_type nr_insert = nr;
  Matrix retval (nr + a.rows (), nc);
  retval.insert (*this, 0, 0);
  retval.insert (a, nr_insert, 0);
  return retval;
}

Matrix
Matrix::stack (const RowVector& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nc != a.numel ())
    (*current_liboctave_error_handler) ("column dimension mismatch for stack");

  octave_idx_type nr_insert = nr;
  Matrix retval (nr + 1, nc);
  retval.insert (*this, 0, 0);
  retval.insert (a, nr_insert, 0);
  return retval;
}

Matrix
Matrix::stack (const ColumnVector& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nc != 1)
    (*current_liboctave_error_handler) ("column dimension mismatch for stack");

  octave_idx_type nr_insert = nr;
  Matrix retval (nr + a.numel (), nc);
  retval.insert (*this, 0, 0);
  retval.insert (a, nr_insert, 0);
  return retval;
}

Matrix
Matrix::stack (const DiagMatrix& a) const
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();
  if (nc != a.cols ())
    (*current_liboctave_error_handler) ("column dimension mismatch for stack");

  octave_idx_type nr_insert = nr;
  Matrix retval (nr + a.rows (), nc);
  retval.insert (*this, 0, 0);
  retval.insert (a, nr_insert, 0);
  return retval;
}

Matrix
real (const ComplexMatrix& a)
{
  return do_mx_unary_op<double, Complex> (a, mx_inline_real);
}

Matrix
imag (const ComplexMatrix& a)
{
  return do_mx_unary_op<double, Complex> (a, mx_inline_imag);
}

Matrix
Matrix::extract (octave_idx_type r1, octave_idx_type c1,
                 octave_idx_type r2, octave_idx_type c2) const
{
  if (r1 > r2) { std::swap (r1, r2); }
  if (c1 > c2) { std::swap (c1, c2); }

  return index (idx_vector (r1, r2+1), idx_vector (c1, c2+1));
}

Matrix
Matrix::extract_n (octave_idx_type r1, octave_idx_type c1, octave_idx_type nr,
                   octave_idx_type nc) const
{
  return index (idx_vector (r1, r1 + nr), idx_vector (c1, c1 + nc));
}

// extract row or column i.

RowVector
Matrix::row (octave_idx_type i) const
{
  return index (idx_vector (i), idx_vector::colon);
}

ColumnVector
Matrix::column (octave_idx_type i) const
{
  return index (idx_vector::colon, idx_vector (i));
}

Matrix
Matrix::inverse (void) const
{
  octave_idx_type info;
  double rcon;
  MatrixType mattype (*this);
  return inverse (mattype, info, rcon, 0, 0);
}

Matrix
Matrix::inverse (octave_idx_type& info) const
{
  double rcon;
  MatrixType mattype (*this);
  return inverse (mattype, info, rcon, 0, 0);
}

Matrix
Matrix::inverse (octave_idx_type& info, double& rcon, bool force,
                 bool calc_cond) const
{
  MatrixType mattype (*this);
  return inverse (mattype, info, rcon, force, calc_cond);
}

Matrix
Matrix::inverse (MatrixType& mattype) const
{
  octave_idx_type info;
  double rcon;
  return inverse (mattype, info, rcon, 0, 0);
}

Matrix
Matrix::inverse (MatrixType &mattype, octave_idx_type& info) const
{
  double rcon;
  return inverse (mattype, info, rcon, 0, 0);
}

Matrix
Matrix::tinverse (MatrixType &mattype, octave_idx_type& info, double& rcon,
                  bool force, bool calc_cond) const
{
  Matrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != nc || nr == 0 || nc == 0)
    (*current_liboctave_error_handler) ("inverse requires square matrix");

  int typ = mattype.type ();
  char uplo = (typ == MatrixType::Lower ? 'L' : 'U');
  char udiag = 'N';
  retval = *this;
  double *tmp_data = retval.fortran_vec ();

  F77_XFCN (dtrtri, DTRTRI, (F77_CONST_CHAR_ARG2 (&uplo, 1),
                             F77_CONST_CHAR_ARG2 (&udiag, 1),
                             nr, tmp_data, nr, info
                             F77_CHAR_ARG_LEN (1)
                             F77_CHAR_ARG_LEN (1)));

  // Throw-away extra info LAPACK gives so as to not change output.
  rcon = 0.0;
  if (info != 0)
    info = -1;
  else if (calc_cond)
    {
      octave_idx_type dtrcon_info = 0;
      char job = '1';

      OCTAVE_LOCAL_BUFFER (double, work, 3 * nr);
      OCTAVE_LOCAL_BUFFER (octave_idx_type, iwork, nr);

      F77_XFCN (dtrcon, DTRCON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                 F77_CONST_CHAR_ARG2 (&uplo, 1),
                                 F77_CONST_CHAR_ARG2 (&udiag, 1),
                                 nr, tmp_data, nr, rcon,
                                 work, iwork, dtrcon_info
                                 F77_CHAR_ARG_LEN (1)
                                 F77_CHAR_ARG_LEN (1)
                                 F77_CHAR_ARG_LEN (1)));

      if (dtrcon_info != 0)
        info = -1;
    }

  if (info == -1 && ! force)
    retval = *this; // Restore matrix contents.

  return retval;
}

Matrix
Matrix::finverse (MatrixType &mattype, octave_idx_type& info, double& rcon,
                  bool force, bool calc_cond) const
{
  Matrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != nc || nr == 0 || nc == 0)
    (*current_liboctave_error_handler) ("inverse requires square matrix");

  Array<octave_idx_type> ipvt (dim_vector (nr, 1));
  octave_idx_type *pipvt = ipvt.fortran_vec ();

  retval = *this;
  double *tmp_data = retval.fortran_vec ();

  Array<double> z (dim_vector (1, 1));
  octave_idx_type lwork = -1;

  // Query the optimum work array size.
  F77_XFCN (dgetri, DGETRI, (nc, tmp_data, nr, pipvt,
                             z.fortran_vec (), lwork, info));

  lwork = static_cast<octave_idx_type> (z(0));
  lwork = (lwork < 2 *nc ? 2*nc : lwork);
  z.resize (dim_vector (lwork, 1));
  double *pz = z.fortran_vec ();

  info = 0;

  // Calculate the norm of the matrix, for later use.
  double anorm = 0;
  if (calc_cond)
    anorm = retval.abs ().sum ().row (static_cast<octave_idx_type>(0))
            .max ();

  F77_XFCN (dgetrf, DGETRF, (nc, nc, tmp_data, nr, pipvt, info));

  // Throw-away extra info LAPACK gives so as to not change output.
  rcon = 0.0;
  if (info != 0)
    info = -1;
  else if (calc_cond)
    {
      octave_idx_type dgecon_info = 0;

      // Now calculate the condition number for non-singular matrix.
      char job = '1';
      Array<octave_idx_type> iz (dim_vector (nc, 1));
      octave_idx_type *piz = iz.fortran_vec ();
      F77_XFCN (dgecon, DGECON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                 nc, tmp_data, nr, anorm,
                                 rcon, pz, piz, dgecon_info
                                 F77_CHAR_ARG_LEN (1)));

      if (dgecon_info != 0)
        info = -1;
    }

  if (info == -1 && ! force)
    retval = *this; // Restore matrix contents.
  else
    {
      octave_idx_type dgetri_info = 0;

      F77_XFCN (dgetri, DGETRI, (nc, tmp_data, nr, pipvt,
                                 pz, lwork, dgetri_info));

      if (dgetri_info != 0)
        info = -1;
    }

  if (info != 0)
    mattype.mark_as_rectangular ();

  return retval;
}

Matrix
Matrix::inverse (MatrixType &mattype, octave_idx_type& info, double& rcon,
                 bool force, bool calc_cond) const
{
  int typ = mattype.type (false);
  Matrix ret;

  if (typ == MatrixType::Unknown)
    typ = mattype.type (*this);

  if (typ == MatrixType::Upper || typ == MatrixType::Lower)
    ret = tinverse (mattype, info, rcon, force, calc_cond);
  else
    {
      if (mattype.is_hermitian ())
        {
          chol<Matrix> chol (*this, info, true, calc_cond);
          if (info == 0)
            {
              if (calc_cond)
                rcon = chol.rcond ();
              else
                rcon = 1.0;
              ret = chol.inverse ();
            }
          else
            mattype.mark_as_unsymmetric ();
        }

      if (! mattype.is_hermitian ())
        ret = finverse (mattype, info, rcon, force, calc_cond);

      if ((mattype.is_hermitian () || calc_cond) && rcon == 0.)
        ret = Matrix (rows (), columns (), octave::numeric_limits<double>::Inf ());
    }

  return ret;
}

Matrix
Matrix::pseudo_inverse (double tol) const
{
  svd<Matrix> result (*this, svd<Matrix>::Type::economy);

  DiagMatrix S = result.singular_values ();
  Matrix U = result.left_singular_matrix ();
  Matrix V = result.right_singular_matrix ();

  ColumnVector sigma = S.extract_diag ();

  octave_idx_type r = sigma.numel () - 1;
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (tol <= 0.0)
    {
      if (nr > nc)
        tol = nr * sigma.elem (0) * std::numeric_limits<double>::epsilon ();
      else
        tol = nc * sigma.elem (0) * std::numeric_limits<double>::epsilon ();
    }

  while (r >= 0 && sigma.elem (r) < tol)
    r--;

  if (r < 0)
    return Matrix (nc, nr, 0.0);
  else
    {
      Matrix Ur = U.extract (0, 0, nr-1, r);
      DiagMatrix D = DiagMatrix (sigma.extract (0, r)).inverse ();
      Matrix Vr = V.extract (0, 0, nc-1, r);
      return Vr * D * Ur.transpose ();
    }
}

#if defined (HAVE_FFTW)

ComplexMatrix
Matrix::fourier (void) const
{
  size_t nr = rows ();
  size_t nc = cols ();

  ComplexMatrix retval (nr, nc);

  size_t npts, nsamples;

  if (nr == 1 || nc == 1)
    {
      npts = nr > nc ? nr : nc;
      nsamples = 1;
    }
  else
    {
      npts = nr;
      nsamples = nc;
    }

  const double *in (fortran_vec ());
  Complex *out (retval.fortran_vec ());

  octave_fftw::fft (in, out, npts, nsamples);

  return retval;
}

ComplexMatrix
Matrix::ifourier (void) const
{
  size_t nr = rows ();
  size_t nc = cols ();

  ComplexMatrix retval (nr, nc);

  size_t npts, nsamples;

  if (nr == 1 || nc == 1)
    {
      npts = nr > nc ? nr : nc;
      nsamples = 1;
    }
  else
    {
      npts = nr;
      nsamples = nc;
    }

  ComplexMatrix tmp (*this);
  Complex *in (tmp.fortran_vec ());
  Complex *out (retval.fortran_vec ());

  octave_fftw::ifft (in, out, npts, nsamples);

  return retval;
}

ComplexMatrix
Matrix::fourier2d (void) const
{
  dim_vector dv (rows (), cols ());

  const double *in = fortran_vec ();
  ComplexMatrix retval (rows (), cols ());
  octave_fftw::fftNd (in, retval.fortran_vec (), 2, dv);

  return retval;
}

ComplexMatrix
Matrix::ifourier2d (void) const
{
  dim_vector dv (rows (), cols ());

  ComplexMatrix retval (*this);
  Complex *out (retval.fortran_vec ());

  octave_fftw::ifftNd (out, out, 2, dv);

  return retval;
}

#else

extern "C"
{
  // Note that the original complex fft routines were not written for
  // double complex arguments.  They have been modified by adding an
  // implicit double precision (a-h,o-z) statement at the beginning of
  // each subroutine.

  F77_RET_T
  F77_FUNC (zffti, ZFFTI) (const F77_INT&, F77_DBLE_CMPLX*);

  F77_RET_T
  F77_FUNC (zfftf, ZFFTF) (const F77_INT&, F77_DBLE_CMPLX*, F77_DBLE_CMPLX*);

  F77_RET_T
  F77_FUNC (zfftb, ZFFTB) (const F77_INT&, F77_DBLE_CMPLX*, F77_DBLE_CMPLX*);
}

ComplexMatrix
Matrix::fourier (void) const
{
  ComplexMatrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  octave_idx_type npts, nsamples;

  if (nr == 1 || nc == 1)
    {
      npts = nr > nc ? nr : nc;
      nsamples = 1;
    }
  else
    {
      npts = nr;
      nsamples = nc;
    }

  octave_idx_type nn = 4*npts+15;

  Array<Complex> wsave (dim_vector (nn, 1));
  Complex *pwsave = wsave.fortran_vec ();

  retval = ComplexMatrix (*this);
  Complex *tmp_data = retval.fortran_vec ();

  F77_FUNC (zffti, ZFFTI) (npts, pwsave);

  for (octave_idx_type j = 0; j < nsamples; j++)
    {
      octave_quit ();

      F77_FUNC (zfftf, ZFFTF) (npts, &tmp_data[npts*j], pwsave);
    }

  return retval;
}

ComplexMatrix
Matrix::ifourier (void) const
{
  ComplexMatrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  octave_idx_type npts, nsamples;

  if (nr == 1 || nc == 1)
    {
      npts = nr > nc ? nr : nc;
      nsamples = 1;
    }
  else
    {
      npts = nr;
      nsamples = nc;
    }

  octave_idx_type nn = 4*npts+15;

  Array<Complex> wsave (dim_vector (nn, 1));
  Complex *pwsave = wsave.fortran_vec ();

  retval = ComplexMatrix (*this);
  Complex *tmp_data = retval.fortran_vec ();

  F77_FUNC (zffti, ZFFTI) (npts, pwsave);

  for (octave_idx_type j = 0; j < nsamples; j++)
    {
      octave_quit ();

      F77_FUNC (zfftb, ZFFTB) (npts, &tmp_data[npts*j], pwsave);
    }

  for (octave_idx_type j = 0; j < npts*nsamples; j++)
    tmp_data[j] = tmp_data[j] / static_cast<double> (npts);

  return retval;
}

ComplexMatrix
Matrix::fourier2d (void) const
{
  ComplexMatrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  octave_idx_type npts, nsamples;

  if (nr == 1 || nc == 1)
    {
      npts = nr > nc ? nr : nc;
      nsamples = 1;
    }
  else
    {
      npts = nr;
      nsamples = nc;
    }

  octave_idx_type nn = 4*npts+15;

  Array<Complex> wsave (dim_vector (nn, 1));
  Complex *pwsave = wsave.fortran_vec ();

  retval = ComplexMatrix (*this);
  Complex *tmp_data = retval.fortran_vec ();

  F77_FUNC (zffti, ZFFTI) (npts, pwsave);

  for (octave_idx_type j = 0; j < nsamples; j++)
    {
      octave_quit ();

      F77_FUNC (zfftf, ZFFTF) (npts, &tmp_data[npts*j], pwsave);
    }

  npts = nc;
  nsamples = nr;
  nn = 4*npts+15;

  wsave.resize (dim_vector (nn, 1));
  pwsave = wsave.fortran_vec ();

  Array<Complex> tmp (dim_vector (npts, 1));
  Complex *prow = tmp.fortran_vec ();

  F77_FUNC (zffti, ZFFTI) (npts, pwsave);

  for (octave_idx_type j = 0; j < nsamples; j++)
    {
      octave_quit ();

      for (octave_idx_type i = 0; i < npts; i++)
        prow[i] = tmp_data[i*nr + j];

      F77_FUNC (zfftf, ZFFTF) (npts, prow, pwsave);

      for (octave_idx_type i = 0; i < npts; i++)
        tmp_data[i*nr + j] = prow[i];
    }

  return retval;
}

ComplexMatrix
Matrix::ifourier2d (void) const
{
  ComplexMatrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  octave_idx_type npts, nsamples;

  if (nr == 1 || nc == 1)
    {
      npts = nr > nc ? nr : nc;
      nsamples = 1;
    }
  else
    {
      npts = nr;
      nsamples = nc;
    }

  octave_idx_type nn = 4*npts+15;

  Array<Complex> wsave (dim_vector (nn, 1));
  Complex *pwsave = wsave.fortran_vec ();

  retval = ComplexMatrix (*this);
  Complex *tmp_data = retval.fortran_vec ();

  F77_FUNC (zffti, ZFFTI) (npts, pwsave);

  for (octave_idx_type j = 0; j < nsamples; j++)
    {
      octave_quit ();

      F77_FUNC (zfftb, ZFFTB) (npts, &tmp_data[npts*j], pwsave);
    }

  for (octave_idx_type j = 0; j < npts*nsamples; j++)
    tmp_data[j] = tmp_data[j] / static_cast<double> (npts);

  npts = nc;
  nsamples = nr;
  nn = 4*npts+15;

  wsave.resize (dim_vector (nn, 1));
  pwsave = wsave.fortran_vec ();

  Array<Complex> tmp (dim_vector (npts, 1));
  Complex *prow = tmp.fortran_vec ();

  F77_FUNC (zffti, ZFFTI) (npts, pwsave);

  for (octave_idx_type j = 0; j < nsamples; j++)
    {
      octave_quit ();

      for (octave_idx_type i = 0; i < npts; i++)
        prow[i] = tmp_data[i*nr + j];

      F77_FUNC (zfftb, ZFFTB) (npts, prow, pwsave);

      for (octave_idx_type i = 0; i < npts; i++)
        tmp_data[i*nr + j] = prow[i] / static_cast<double> (npts);
    }

  return retval;
}

#endif

DET
Matrix::determinant (void) const
{
  octave_idx_type info;
  double rcon;
  return determinant (info, rcon, 0);
}

DET
Matrix::determinant (octave_idx_type& info) const
{
  double rcon;
  return determinant (info, rcon, 0);
}

DET
Matrix::determinant (octave_idx_type& info, double& rcon, bool calc_cond) const
{
  MatrixType mattype (*this);
  return determinant (mattype, info, rcon, calc_cond);
}

DET
Matrix::determinant (MatrixType& mattype,
                     octave_idx_type& info, double& rcon, bool calc_cond) const
{
  DET retval (1.0);

  info = 0;
  rcon = 0.0;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != nc)
    (*current_liboctave_error_handler) ("matrix must be square");

  volatile int typ = mattype.type ();

  // Even though the matrix is marked as singular (Rectangular), we may
  // still get a useful number from the LU factorization, because it always
  // completes.

  if (typ == MatrixType::Unknown)
    typ = mattype.type (*this);
  else if (typ == MatrixType::Rectangular)
    typ = MatrixType::Full;

  if (typ == MatrixType::Lower || typ == MatrixType::Upper)
    {
      for (octave_idx_type i = 0; i < nc; i++)
        retval *= elem (i,i);
    }
  else if (typ == MatrixType::Hermitian)
    {
      Matrix atmp = *this;
      double *tmp_data = atmp.fortran_vec ();

      double anorm = 0;
      if (calc_cond) anorm = xnorm (*this, 1);

      char job = 'L';
      F77_XFCN (dpotrf, DPOTRF, (F77_CONST_CHAR_ARG2 (&job, 1), nr,
                                 tmp_data, nr, info
                                 F77_CHAR_ARG_LEN (1)));

      if (info != 0)
        {
          rcon = 0.0;
          mattype.mark_as_unsymmetric ();
          typ = MatrixType::Full;
        }
      else
        {
          Array<double> z (dim_vector (3 * nc, 1));
          double *pz = z.fortran_vec ();
          Array<octave_idx_type> iz (dim_vector (nc, 1));
          octave_idx_type *piz = iz.fortran_vec ();

          F77_XFCN (dpocon, DPOCON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                     nr, tmp_data, nr, anorm,
                                     rcon, pz, piz, info
                                     F77_CHAR_ARG_LEN (1)));

          if (info != 0)
            rcon = 0.0;

          for (octave_idx_type i = 0; i < nc; i++)
            retval *= atmp (i,i);

          retval = retval.square ();
        }
    }
  else if (typ != MatrixType::Full)
    (*current_liboctave_error_handler) ("det: invalid dense matrix type");

  if (typ == MatrixType::Full)
    {
      Array<octave_idx_type> ipvt (dim_vector (nr, 1));
      octave_idx_type *pipvt = ipvt.fortran_vec ();

      Matrix atmp = *this;
      double *tmp_data = atmp.fortran_vec ();

      info = 0;

      // Calculate the norm of the matrix, for later use.
      double anorm = 0;
      if (calc_cond) anorm = xnorm (*this, 1);

      F77_XFCN (dgetrf, DGETRF, (nr, nr, tmp_data, nr, pipvt, info));

      // Throw-away extra info LAPACK gives so as to not change output.
      rcon = 0.0;
      if (info != 0)
        {
          info = -1;
          retval = DET ();
        }
      else
        {
          if (calc_cond)
            {
              // Now calc the condition number for non-singular matrix.
              char job = '1';
              Array<double> z (dim_vector (4 * nc, 1));
              double *pz = z.fortran_vec ();
              Array<octave_idx_type> iz (dim_vector (nc, 1));
              octave_idx_type *piz = iz.fortran_vec ();

              F77_XFCN (dgecon, DGECON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                         nc, tmp_data, nr, anorm,
                                         rcon, pz, piz, info
                                         F77_CHAR_ARG_LEN (1)));
            }

          if (info != 0)
            {
              info = -1;
              retval = DET ();
            }
          else
            {
              for (octave_idx_type i = 0; i < nc; i++)
                {
                  double c = atmp(i,i);
                  retval *= (ipvt(i) != (i+1)) ? -c : c;
                }
            }
        }
    }

  return retval;
}

double
Matrix::rcond (void) const
{
  MatrixType mattype (*this);
  return rcond (mattype);
}

double
Matrix::rcond (MatrixType &mattype) const
{
  double rcon = octave::numeric_limits<double>::NaN ();
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != nc)
    (*current_liboctave_error_handler) ("matrix must be square");

  if (nr == 0 || nc == 0)
    rcon = octave::numeric_limits<double>::Inf ();
  else
    {
      volatile int typ = mattype.type ();

      if (typ == MatrixType::Unknown)
        typ = mattype.type (*this);

      // Only calculate the condition number for LU/Cholesky
      if (typ == MatrixType::Upper)
        {
          const double *tmp_data = fortran_vec ();
          octave_idx_type info = 0;
          char norm = '1';
          char uplo = 'U';
          char dia = 'N';

          Array<double> z (dim_vector (3 * nc, 1));
          double *pz = z.fortran_vec ();
          Array<octave_idx_type> iz (dim_vector (nc, 1));
          octave_idx_type *piz = iz.fortran_vec ();

          F77_XFCN (dtrcon, DTRCON, (F77_CONST_CHAR_ARG2 (&norm, 1),
                                     F77_CONST_CHAR_ARG2 (&uplo, 1),
                                     F77_CONST_CHAR_ARG2 (&dia, 1),
                                     nr, tmp_data, nr, rcon,
                                     pz, piz, info
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)));

          if (info != 0)
            rcon = 0.0;
        }
      else if (typ == MatrixType::Permuted_Upper)
        (*current_liboctave_error_handler)
          ("permuted triangular matrix not implemented");
      else if (typ == MatrixType::Lower)
        {
          const double *tmp_data = fortran_vec ();
          octave_idx_type info = 0;
          char norm = '1';
          char uplo = 'L';
          char dia = 'N';

          Array<double> z (dim_vector (3 * nc, 1));
          double *pz = z.fortran_vec ();
          Array<octave_idx_type> iz (dim_vector (nc, 1));
          octave_idx_type *piz = iz.fortran_vec ();

          F77_XFCN (dtrcon, DTRCON, (F77_CONST_CHAR_ARG2 (&norm, 1),
                                     F77_CONST_CHAR_ARG2 (&uplo, 1),
                                     F77_CONST_CHAR_ARG2 (&dia, 1),
                                     nr, tmp_data, nr, rcon,
                                     pz, piz, info
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)));

          if (info != 0)
            rcon = 0.0;
        }
      else if (typ == MatrixType::Permuted_Lower)
        (*current_liboctave_error_handler)
          ("permuted triangular matrix not implemented");
      else if (typ == MatrixType::Full || typ == MatrixType::Hermitian)
        {
          double anorm = -1.0;

          if (typ == MatrixType::Hermitian)
            {
              octave_idx_type info = 0;
              char job = 'L';

              Matrix atmp = *this;
              double *tmp_data = atmp.fortran_vec ();

              anorm = atmp.abs().sum().
                      row(static_cast<octave_idx_type>(0)).max();

              F77_XFCN (dpotrf, DPOTRF, (F77_CONST_CHAR_ARG2 (&job, 1), nr,
                                         tmp_data, nr, info
                                         F77_CHAR_ARG_LEN (1)));

              if (info != 0)
                {
                  rcon = 0.0;
                  mattype.mark_as_unsymmetric ();
                  typ = MatrixType::Full;
                }
              else
                {
                  Array<double> z (dim_vector (3 * nc, 1));
                  double *pz = z.fortran_vec ();
                  Array<octave_idx_type> iz (dim_vector (nc, 1));
                  octave_idx_type *piz = iz.fortran_vec ();

                  F77_XFCN (dpocon, DPOCON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                             nr, tmp_data, nr, anorm,
                                             rcon, pz, piz, info
                                             F77_CHAR_ARG_LEN (1)));

                  if (info != 0)
                    rcon = 0.0;
                }
            }

          if (typ == MatrixType::Full)
            {
              octave_idx_type info = 0;

              Matrix atmp = *this;
              double *tmp_data = atmp.fortran_vec ();

              Array<octave_idx_type> ipvt (dim_vector (nr, 1));
              octave_idx_type *pipvt = ipvt.fortran_vec ();

              if (anorm < 0.)
                anorm = atmp.abs ().sum ().
                        row(static_cast<octave_idx_type>(0)).max ();

              Array<double> z (dim_vector (4 * nc, 1));
              double *pz = z.fortran_vec ();
              Array<octave_idx_type> iz (dim_vector (nc, 1));
              octave_idx_type *piz = iz.fortran_vec ();

              F77_XFCN (dgetrf, DGETRF, (nr, nr, tmp_data, nr, pipvt, info));

              if (info != 0)
                {
                  rcon = 0.0;
                  mattype.mark_as_rectangular ();
                }
              else
                {
                  char job = '1';
                  F77_XFCN (dgecon, DGECON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                             nc, tmp_data, nr, anorm,
                                             rcon, pz, piz, info
                                             F77_CHAR_ARG_LEN (1)));

                  if (info != 0)
                    rcon = 0.0;
                }
            }
        }
      else
        rcon = 0.0;
    }

  return rcon;
}

Matrix
Matrix::utsolve (MatrixType &mattype, const Matrix& b, octave_idx_type& info,
                 double& rcon, solve_singularity_handler sing_handler,
                 bool calc_cond, blas_trans_type transt) const
{
  Matrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != b.rows ())
    (*current_liboctave_error_handler)
      ("matrix dimension mismatch solution of linear equations");

  if (nr == 0 || nc == 0 || b.cols () == 0)
    retval = Matrix (nc, b.cols (), 0.0);
  else
    {
      volatile int typ = mattype.type ();

      if (typ != MatrixType::Permuted_Upper && typ != MatrixType::Upper)
        (*current_liboctave_error_handler) ("incorrect matrix type");

      octave_idx_type b_nc = b.cols ();
      rcon = 1.;
      info = 0;

      if (typ == MatrixType::Permuted_Upper)
        (*current_liboctave_error_handler)
          ("permuted triangular matrix not implemented");

      const double *tmp_data = fortran_vec ();

      retval = b;
      double *result = retval.fortran_vec ();

      char uplo = 'U';
      char trans = get_blas_char (transt);
      char dia = 'N';

      F77_XFCN (dtrtrs, DTRTRS, (F77_CONST_CHAR_ARG2 (&uplo, 1),
                                 F77_CONST_CHAR_ARG2 (&trans, 1),
                                 F77_CONST_CHAR_ARG2 (&dia, 1),
                                 nr, b_nc, tmp_data, nr,
                                 result, nr, info
                                 F77_CHAR_ARG_LEN (1)
                                 F77_CHAR_ARG_LEN (1)
                                 F77_CHAR_ARG_LEN (1)));

      if (calc_cond)
        {
          char norm = '1';
          uplo = 'U';
          dia = 'N';

          Array<double> z (dim_vector (3 * nc, 1));
          double *pz = z.fortran_vec ();
          Array<octave_idx_type> iz (dim_vector (nc, 1));
          octave_idx_type *piz = iz.fortran_vec ();

          F77_XFCN (dtrcon, DTRCON, (F77_CONST_CHAR_ARG2 (&norm, 1),
                                     F77_CONST_CHAR_ARG2 (&uplo, 1),
                                     F77_CONST_CHAR_ARG2 (&dia, 1),
                                     nr, tmp_data, nr, rcon,
                                     pz, piz, info
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)));

          if (info != 0)
            info = -2;

          volatile double rcond_plus_one = rcon + 1.0;

          if (rcond_plus_one == 1.0 || octave::math::isnan (rcon))
            {
              info = -2;

              if (sing_handler)
                sing_handler (rcon);
              else
                warn_singular_matrix (rcon);
            }
        }
    }

  return retval;
}

Matrix
Matrix::ltsolve (MatrixType &mattype, const Matrix& b, octave_idx_type& info,
                 double& rcon, solve_singularity_handler sing_handler,
                 bool calc_cond, blas_trans_type transt) const
{
  Matrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != b.rows ())
    (*current_liboctave_error_handler)
      ("matrix dimension mismatch solution of linear equations");

  if (nr == 0 || nc == 0 || b.cols () == 0)
    retval = Matrix (nc, b.cols (), 0.0);
  else
    {
      volatile int typ = mattype.type ();

      if (typ != MatrixType::Permuted_Lower && typ != MatrixType::Lower)
        (*current_liboctave_error_handler) ("incorrect matrix type");

      octave_idx_type b_nc = b.cols ();
      rcon = 1.;
      info = 0;

      if (typ == MatrixType::Permuted_Lower)
        (*current_liboctave_error_handler)
          ("permuted triangular matrix not implemented");

      const double *tmp_data = fortran_vec ();

      retval = b;
      double *result = retval.fortran_vec ();

      char uplo = 'L';
      char trans = get_blas_char (transt);
      char dia = 'N';

      F77_XFCN (dtrtrs, DTRTRS, (F77_CONST_CHAR_ARG2 (&uplo, 1),
                                 F77_CONST_CHAR_ARG2 (&trans, 1),
                                 F77_CONST_CHAR_ARG2 (&dia, 1),
                                 nr, b_nc, tmp_data, nr,
                                 result, nr, info
                                 F77_CHAR_ARG_LEN (1)
                                 F77_CHAR_ARG_LEN (1)
                                 F77_CHAR_ARG_LEN (1)));

      if (calc_cond)
        {
          char norm = '1';
          uplo = 'L';
          dia = 'N';

          Array<double> z (dim_vector (3 * nc, 1));
          double *pz = z.fortran_vec ();
          Array<octave_idx_type> iz (dim_vector (nc, 1));
          octave_idx_type *piz = iz.fortran_vec ();

          F77_XFCN (dtrcon, DTRCON, (F77_CONST_CHAR_ARG2 (&norm, 1),
                                     F77_CONST_CHAR_ARG2 (&uplo, 1),
                                     F77_CONST_CHAR_ARG2 (&dia, 1),
                                     nr, tmp_data, nr, rcon,
                                     pz, piz, info
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)
                                     F77_CHAR_ARG_LEN (1)));

          if (info != 0)
            info = -2;

          volatile double rcond_plus_one = rcon + 1.0;

          if (rcond_plus_one == 1.0 || octave::math::isnan (rcon))
            {
              info = -2;

              if (sing_handler)
                sing_handler (rcon);
              else
                warn_singular_matrix (rcon);
            }
        }
    }

  return retval;
}

Matrix
Matrix::fsolve (MatrixType &mattype, const Matrix& b, octave_idx_type& info,
                double& rcon, solve_singularity_handler sing_handler,
                bool calc_cond) const
{
  Matrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr != nc || nr != b.rows ())
    (*current_liboctave_error_handler)
      ("matrix dimension mismatch solution of linear equations");

  if (nr == 0 || b.cols () == 0)
    retval = Matrix (nc, b.cols (), 0.0);
  else
    {
      volatile int typ = mattype.type ();

      // Calculate the norm of the matrix, for later use.
      double anorm = -1.;

      if (typ == MatrixType::Hermitian)
        {
          info = 0;
          char job = 'L';

          Matrix atmp = *this;
          double *tmp_data = atmp.fortran_vec ();

          anorm = atmp.abs().sum().row(static_cast<octave_idx_type>(0)).max();

          F77_XFCN (dpotrf, DPOTRF, (F77_CONST_CHAR_ARG2 (&job, 1), nr,
                                     tmp_data, nr, info
                                     F77_CHAR_ARG_LEN (1)));

          // Throw-away extra info LAPACK gives so as to not change output.
          rcon = 0.0;
          if (info != 0)
            {
              info = -2;

              mattype.mark_as_unsymmetric ();
              typ = MatrixType::Full;
            }
          else
            {
              if (calc_cond)
                {
                  Array<double> z (dim_vector (3 * nc, 1));
                  double *pz = z.fortran_vec ();
                  Array<octave_idx_type> iz (dim_vector (nc, 1));
                  octave_idx_type *piz = iz.fortran_vec ();

                  F77_XFCN (dpocon, DPOCON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                             nr, tmp_data, nr, anorm,
                                             rcon, pz, piz, info
                                             F77_CHAR_ARG_LEN (1)));

                  if (info != 0)
                    info = -2;

                  volatile double rcond_plus_one = rcon + 1.0;

                  if (rcond_plus_one == 1.0 || octave::math::isnan (rcon))
                    {
                      info = -2;

                      if (sing_handler)
                        sing_handler (rcon);
                      else
                        warn_singular_matrix (rcon);
                    }
                }

              if (info == 0)
                {
                  retval = b;
                  double *result = retval.fortran_vec ();

                  octave_idx_type b_nc = b.cols ();

                  F77_XFCN (dpotrs, DPOTRS, (F77_CONST_CHAR_ARG2 (&job, 1),
                                             nr, b_nc, tmp_data, nr,
                                             result, b.rows (), info
                                             F77_CHAR_ARG_LEN (1)));
                }
              else
                {
                  mattype.mark_as_unsymmetric ();
                  typ = MatrixType::Full;
                }
            }
        }

      if (typ == MatrixType::Full)
        {
          info = 0;

          Array<octave_idx_type> ipvt (dim_vector (nr, 1));
          octave_idx_type *pipvt = ipvt.fortran_vec ();

          Matrix atmp = *this;
          double *tmp_data = atmp.fortran_vec ();

          if (anorm < 0.)
            anorm = atmp.abs().sum().row(static_cast<octave_idx_type>(0)).max();

          Array<double> z (dim_vector (4 * nc, 1));
          double *pz = z.fortran_vec ();
          Array<octave_idx_type> iz (dim_vector (nc, 1));
          octave_idx_type *piz = iz.fortran_vec ();

          F77_XFCN (dgetrf, DGETRF, (nr, nr, tmp_data, nr, pipvt, info));

          // Throw-away extra info LAPACK gives so as to not change output.
          rcon = 0.0;
          if (info != 0)
            {
              info = -2;

              if (sing_handler)
                sing_handler (rcon);
              else
                warn_singular_matrix ();

              mattype.mark_as_rectangular ();
            }
          else
            {
              if (calc_cond)
                {
                  // Now calculate the condition number for
                  // non-singular matrix.
                  char job = '1';
                  F77_XFCN (dgecon, DGECON, (F77_CONST_CHAR_ARG2 (&job, 1),
                                             nc, tmp_data, nr, anorm,
                                             rcon, pz, piz, info
                                             F77_CHAR_ARG_LEN (1)));

                  if (info != 0)
                    info = -2;

                  volatile double rcond_plus_one = rcon + 1.0;

                  if (rcond_plus_one == 1.0 || octave::math::isnan (rcon))
                    {
                      info = -2;

                      if (sing_handler)
                        sing_handler (rcon);
                      else
                        warn_singular_matrix (rcon);
                    }
                }

              if (info == 0)
                {
                  retval = b;
                  double *result = retval.fortran_vec ();

                  octave_idx_type b_nc = b.cols ();

                  char job = 'N';
                  F77_XFCN (dgetrs, DGETRS, (F77_CONST_CHAR_ARG2 (&job, 1),
                                             nr, b_nc, tmp_data, nr,
                                             pipvt, result, b.rows (), info
                                             F77_CHAR_ARG_LEN (1)));
                }
              else
                mattype.mark_as_rectangular ();
            }
        }
      else if (typ != MatrixType::Hermitian)
        (*current_liboctave_error_handler) ("incorrect matrix type");
    }

  return retval;
}

Matrix
Matrix::solve (MatrixType &typ, const Matrix& b) const
{
  octave_idx_type info;
  double rcon;
  return solve (typ, b, info, rcon, 0);
}

Matrix
Matrix::solve (MatrixType &typ, const Matrix& b, octave_idx_type& info) const
{
  double rcon;
  return solve (typ, b, info, rcon, 0);
}

Matrix
Matrix::solve (MatrixType &typ, const Matrix& b, octave_idx_type& info,
               double& rcon) const
{
  return solve (typ, b, info, rcon, 0);
}

Matrix
Matrix::solve (MatrixType &mattype, const Matrix& b, octave_idx_type& info,
               double& rcon, solve_singularity_handler sing_handler,
               bool singular_fallback, blas_trans_type transt) const
{
  Matrix retval;
  int typ = mattype.type ();

  if (typ == MatrixType::Unknown)
    typ = mattype.type (*this);

  // Only calculate the condition number for LU/Cholesky
  if (typ == MatrixType::Upper || typ == MatrixType::Permuted_Upper)
    retval = utsolve (mattype, b, info, rcon, sing_handler, true, transt);
  else if (typ == MatrixType::Lower || typ == MatrixType::Permuted_Lower)
    retval = ltsolve (mattype, b, info, rcon, sing_handler, true, transt);
  else if (transt == blas_trans || transt == blas_conj_trans)
    return transpose ().solve (mattype, b, info, rcon, sing_handler,
                               singular_fallback);
  else if (typ == MatrixType::Full || typ == MatrixType::Hermitian)
    retval = fsolve (mattype, b, info, rcon, sing_handler, true);
  else if (typ != MatrixType::Rectangular)
    (*current_liboctave_error_handler) ("unknown matrix type");

  // Rectangular or one of the above solvers flags a singular matrix
  if (singular_fallback && mattype.type () == MatrixType::Rectangular)
    {
      octave_idx_type rank;
      retval = lssolve (b, info, rank, rcon);
    }

  return retval;
}

ComplexMatrix
Matrix::solve (MatrixType &typ, const ComplexMatrix& b) const
{
  octave_idx_type info;
  double rcon;
  return solve (typ, b, info, rcon, 0);
}

ComplexMatrix
Matrix::solve (MatrixType &typ, const ComplexMatrix& b,
               octave_idx_type& info) const
{
  double rcon;
  return solve (typ, b, info, rcon, 0);
}

ComplexMatrix
Matrix::solve (MatrixType &typ, const ComplexMatrix& b, octave_idx_type& info,
               double& rcon) const
{
  return solve (typ, b, info, rcon, 0);
}

static Matrix
stack_complex_matrix (const ComplexMatrix& cm)
{
  octave_idx_type m = cm.rows ();
  octave_idx_type n = cm.cols ();
  octave_idx_type nel = m*n;
  Matrix retval (m, 2*n);
  const Complex *cmd = cm.data ();
  double *rd = retval.fortran_vec ();
  for (octave_idx_type i = 0; i < nel; i++)
    {
      rd[i] = std::real (cmd[i]);
      rd[nel+i] = std::imag (cmd[i]);
    }
  return retval;
}

static ComplexMatrix
unstack_complex_matrix (const Matrix& sm)
{
  octave_idx_type m = sm.rows ();
  octave_idx_type n = sm.cols () / 2;
  octave_idx_type nel = m*n;
  ComplexMatrix retval (m, n);
  const double *smd = sm.data ();
  Complex *rd = retval.fortran_vec ();
  for (octave_idx_type i = 0; i < nel; i++)
    rd[i] = Complex (smd[i], smd[nel+i]);
  return retval;
}

ComplexMatrix
Matrix::solve (MatrixType &typ, const ComplexMatrix& b, octave_idx_type& info,
               double& rcon, solve_singularity_handler sing_handler,
               bool singular_fallback, blas_trans_type transt) const
{
  Matrix tmp = stack_complex_matrix (b);
  tmp = solve (typ, tmp, info, rcon, sing_handler, singular_fallback, transt);
  return unstack_complex_matrix (tmp);
}

ColumnVector
Matrix::solve (MatrixType &typ, const ColumnVector& b) const
{
  octave_idx_type info; double rcon;
  return solve (typ, b, info, rcon);
}

ColumnVector
Matrix::solve (MatrixType &typ, const ColumnVector& b,
               octave_idx_type& info) const
{
  double rcon;
  return solve (typ, b, info, rcon);
}

ColumnVector
Matrix::solve (MatrixType &typ, const ColumnVector& b, octave_idx_type& info,
               double& rcon) const
{
  return solve (typ, b, info, rcon, 0);
}

ColumnVector
Matrix::solve (MatrixType &typ, const ColumnVector& b, octave_idx_type& info,
               double& rcon, solve_singularity_handler sing_handler,
               blas_trans_type transt) const
{
  Matrix tmp (b);
  tmp = solve (typ, tmp, info, rcon, sing_handler, true, transt);
  return tmp.column (static_cast<octave_idx_type> (0));
}

ComplexColumnVector
Matrix::solve (MatrixType &typ, const ComplexColumnVector& b) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (typ, b);
}

ComplexColumnVector
Matrix::solve (MatrixType &typ, const ComplexColumnVector& b,
               octave_idx_type& info) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (typ, b, info);
}

ComplexColumnVector
Matrix::solve (MatrixType &typ, const ComplexColumnVector& b,
               octave_idx_type& info, double& rcon) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (typ, b, info, rcon);
}

ComplexColumnVector
Matrix::solve (MatrixType &typ, const ComplexColumnVector& b,
               octave_idx_type& info, double& rcon,
               solve_singularity_handler sing_handler,
               blas_trans_type transt) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (typ, b, info, rcon, sing_handler, transt);
}

Matrix
Matrix::solve (const Matrix& b) const
{
  octave_idx_type info;
  double rcon;
  return solve (b, info, rcon, 0);
}

Matrix
Matrix::solve (const Matrix& b, octave_idx_type& info) const
{
  double rcon;
  return solve (b, info, rcon, 0);
}

Matrix
Matrix::solve (const Matrix& b, octave_idx_type& info, double& rcon) const
{
  return solve (b, info, rcon, 0);
}

Matrix
Matrix::solve (const Matrix& b, octave_idx_type& info,
               double& rcon, solve_singularity_handler sing_handler,
               blas_trans_type transt) const
{
  MatrixType mattype (*this);
  return solve (mattype, b, info, rcon, sing_handler, true, transt);
}

ComplexMatrix
Matrix::solve (const ComplexMatrix& b) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b);
}

ComplexMatrix
Matrix::solve (const ComplexMatrix& b, octave_idx_type& info) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b, info);
}

ComplexMatrix
Matrix::solve (const ComplexMatrix& b, octave_idx_type& info,
               double& rcon) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b, info, rcon);
}

ComplexMatrix
Matrix::solve (const ComplexMatrix& b, octave_idx_type& info, double& rcon,
               solve_singularity_handler sing_handler,
               blas_trans_type transt) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b, info, rcon, sing_handler, transt);
}

ColumnVector
Matrix::solve (const ColumnVector& b) const
{
  octave_idx_type info; double rcon;
  return solve (b, info, rcon);
}

ColumnVector
Matrix::solve (const ColumnVector& b, octave_idx_type& info) const
{
  double rcon;
  return solve (b, info, rcon);
}

ColumnVector
Matrix::solve (const ColumnVector& b, octave_idx_type& info, double& rcon) const
{
  return solve (b, info, rcon, 0);
}

ColumnVector
Matrix::solve (const ColumnVector& b, octave_idx_type& info, double& rcon,
               solve_singularity_handler sing_handler,
               blas_trans_type transt) const
{
  MatrixType mattype (*this);
  return solve (mattype, b, info, rcon, sing_handler, transt);
}

ComplexColumnVector
Matrix::solve (const ComplexColumnVector& b) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b);
}

ComplexColumnVector
Matrix::solve (const ComplexColumnVector& b, octave_idx_type& info) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b, info);
}

ComplexColumnVector
Matrix::solve (const ComplexColumnVector& b, octave_idx_type& info,
               double& rcon) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b, info, rcon);
}

ComplexColumnVector
Matrix::solve (const ComplexColumnVector& b, octave_idx_type& info,
               double& rcon,
               solve_singularity_handler sing_handler,
               blas_trans_type transt) const
{
  ComplexMatrix tmp (*this);
  return tmp.solve (b, info, rcon, sing_handler, transt);
}

Matrix
Matrix::lssolve (const Matrix& b) const
{
  octave_idx_type info;
  octave_idx_type rank;
  double rcon;
  return lssolve (b, info, rank, rcon);
}

Matrix
Matrix::lssolve (const Matrix& b, octave_idx_type& info) const
{
  octave_idx_type rank;
  double rcon;
  return lssolve (b, info, rank, rcon);
}

Matrix
Matrix::lssolve (const Matrix& b, octave_idx_type& info,
                 octave_idx_type& rank) const
{
  double rcon;
  return lssolve (b, info, rank, rcon);
}

Matrix
Matrix::lssolve (const Matrix& b, octave_idx_type& info,
                 octave_idx_type& rank, double &rcon) const
{
  Matrix retval;

  octave_idx_type nrhs = b.cols ();

  octave_idx_type m = rows ();
  octave_idx_type n = cols ();

  if (m != b.rows ())
    (*current_liboctave_error_handler)
      ("matrix dimension mismatch solution of linear equations");

  if (m == 0 || n == 0 || b.cols () == 0)
    retval = Matrix (n, b.cols (), 0.0);
  else
    {
      volatile octave_idx_type minmn = (m < n ? m : n);
      octave_idx_type maxmn = m > n ? m : n;
      rcon = -1.0;
      if (m != n)
        {
          retval = Matrix (maxmn, nrhs, 0.0);

          for (octave_idx_type j = 0; j < nrhs; j++)
            for (octave_idx_type i = 0; i < m; i++)
              retval.elem (i, j) = b.elem (i, j);
        }
      else
        retval = b;

      Matrix atmp = *this;
      double *tmp_data = atmp.fortran_vec ();

      double *pretval = retval.fortran_vec ();
      Array<double> s (dim_vector (minmn, 1));
      double *ps = s.fortran_vec ();

      // Ask DGELSD what the dimension of WORK should be.
      octave_idx_type lwork = -1;

      Array<double> work (dim_vector (1, 1));

      octave_idx_type smlsiz;
      F77_FUNC (xilaenv, XILAENV) (9, F77_CONST_CHAR_ARG2 ("DGELSD", 6),
                                   F77_CONST_CHAR_ARG2 (" ", 1),
                                   0, 0, 0, 0, smlsiz
                                   F77_CHAR_ARG_LEN (6)
                                   F77_CHAR_ARG_LEN (1));

      octave_idx_type mnthr;
      F77_FUNC (xilaenv, XILAENV) (6, F77_CONST_CHAR_ARG2 ("DGELSD", 6),
                                   F77_CONST_CHAR_ARG2 (" ", 1),
                                   m, n, nrhs, -1, mnthr
                                   F77_CHAR_ARG_LEN (6)
                                   F77_CHAR_ARG_LEN (1));

      // We compute the size of iwork because DGELSD in older versions
      // of LAPACK does not return it on a query call.
      double dminmn = static_cast<double> (minmn);
      double dsmlsizp1 = static_cast<double> (smlsiz+1);
      double tmp = octave::math::log2 (dminmn / dsmlsizp1);

      octave_idx_type nlvl = static_cast<octave_idx_type> (tmp) + 1;
      if (nlvl < 0)
        nlvl = 0;

      octave_idx_type liwork = 3 * minmn * nlvl + 11 * minmn;
      if (liwork < 1)
        liwork = 1;
      Array<octave_idx_type> iwork (dim_vector (liwork, 1));
      octave_idx_type* piwork = iwork.fortran_vec ();

      F77_XFCN (dgelsd, DGELSD, (m, n, nrhs, tmp_data, m, pretval, maxmn,
                                 ps, rcon, rank, work.fortran_vec (),
                                 lwork, piwork, info));

      // The workspace query is broken in at least LAPACK 3.0.0
      // through 3.1.1 when n >= mnthr.  The obtuse formula below
      // should provide sufficient workspace for DGELSD to operate
      // efficiently.
      if (n > m && n >= mnthr)
        {
          const octave_idx_type wlalsd
            = 9*m + 2*m*smlsiz + 8*m*nlvl + m*nrhs + (smlsiz+1)*(smlsiz+1);

          octave_idx_type addend = m;

          if (2*m-4 > addend)
            addend = 2*m-4;

          if (nrhs > addend)
            addend = nrhs;

          if (n-3*m > addend)
            addend = n-3*m;

          if (wlalsd > addend)
            addend = wlalsd;

          const octave_idx_type lworkaround = 4*m + m*m + addend;

          if (work(0) < lworkaround)
            work(0) = lworkaround;
        }
      else if (m >= n)
        {
          octave_idx_type lworkaround
            = 12*n + 2*n*smlsiz + 8*n*nlvl + n*nrhs + (smlsiz+1)*(smlsiz+1);

          if (work(0) < lworkaround)
            work(0) = lworkaround;
        }

      lwork = static_cast<octave_idx_type> (work(0));
      work.resize (dim_vector (lwork, 1));

      F77_XFCN (dgelsd, DGELSD, (m, n, nrhs, tmp_data, m, pretval,
                                 maxmn, ps, rcon, rank,
                                 work.fortran_vec (), lwork,
                                 piwork, info));

      if (s.elem (0) == 0.0)
        rcon = 0.0;
      else
        rcon = s.elem (minmn - 1) / s.elem (0);

      retval.resize (n, nrhs);
    }

  return retval;
}

ComplexMatrix
Matrix::lssolve (const ComplexMatrix& b) const
{
  ComplexMatrix tmp (*this);
  octave_idx_type info;
  octave_idx_type rank;
  double rcon;
  return tmp.lssolve (b, info, rank, rcon);
}

ComplexMatrix
Matrix::lssolve (const ComplexMatrix& b, octave_idx_type& info) const
{
  ComplexMatrix tmp (*this);
  octave_idx_type rank;
  double rcon;
  return tmp.lssolve (b, info, rank, rcon);
}

ComplexMatrix
Matrix::lssolve (const ComplexMatrix& b, octave_idx_type& info,
                 octave_idx_type& rank) const
{
  ComplexMatrix tmp (*this);
  double rcon;
  return tmp.lssolve (b, info, rank, rcon);
}

ComplexMatrix
Matrix::lssolve (const ComplexMatrix& b, octave_idx_type& info,
                 octave_idx_type& rank, double& rcon) const
{
  ComplexMatrix tmp (*this);
  return tmp.lssolve (b, info, rank, rcon);
}

ColumnVector
Matrix::lssolve (const ColumnVector& b) const
{
  octave_idx_type info;
  octave_idx_type rank;
  double rcon;
  return lssolve (b, info, rank, rcon);
}

ColumnVector
Matrix::lssolve (const ColumnVector& b, octave_idx_type& info) const
{
  octave_idx_type rank;
  double rcon;
  return lssolve (b, info, rank, rcon);
}

ColumnVector
Matrix::lssolve (const ColumnVector& b, octave_idx_type& info,
                 octave_idx_type& rank) const
{
  double rcon;
  return lssolve (b, info, rank, rcon);
}

ColumnVector
Matrix::lssolve (const ColumnVector& b, octave_idx_type& info,
                 octave_idx_type& rank, double &rcon) const
{
  ColumnVector retval;

  octave_idx_type nrhs = 1;

  octave_idx_type m = rows ();
  octave_idx_type n = cols ();

  if (m != b.numel ())
    (*current_liboctave_error_handler)
      ("matrix dimension mismatch solution of linear equations");

  if (m == 0 || n == 0)
    retval = ColumnVector (n, 0.0);
  else
    {
      volatile octave_idx_type minmn = (m < n ? m : n);
      octave_idx_type maxmn = m > n ? m : n;
      rcon = -1.0;

      if (m != n)
        {
          retval = ColumnVector (maxmn, 0.0);

          for (octave_idx_type i = 0; i < m; i++)
            retval.elem (i) = b.elem (i);
        }
      else
        retval = b;

      Matrix atmp = *this;
      double *tmp_data = atmp.fortran_vec ();

      double *pretval = retval.fortran_vec ();
      Array<double> s (dim_vector (minmn, 1));
      double *ps = s.fortran_vec ();

      // Ask DGELSD what the dimension of WORK should be.
      octave_idx_type lwork = -1;

      Array<double> work (dim_vector (1, 1));

      octave_idx_type smlsiz;
      F77_FUNC (xilaenv, XILAENV) (9, F77_CONST_CHAR_ARG2 ("DGELSD", 6),
                                   F77_CONST_CHAR_ARG2 (" ", 1),
                                   0, 0, 0, 0, smlsiz
                                   F77_CHAR_ARG_LEN (6)
                                   F77_CHAR_ARG_LEN (1));

      // We compute the size of iwork because DGELSD in older versions
      // of LAPACK does not return it on a query call.
      double dminmn = static_cast<double> (minmn);
      double dsmlsizp1 = static_cast<double> (smlsiz+1);
      double tmp = octave::math::log2 (dminmn / dsmlsizp1);

      octave_idx_type nlvl = static_cast<octave_idx_type> (tmp) + 1;
      if (nlvl < 0)
        nlvl = 0;

      octave_idx_type liwork = 3 * minmn * nlvl + 11 * minmn;
      if (liwork < 1)
        liwork = 1;
      Array<octave_idx_type> iwork (dim_vector (liwork, 1));
      octave_idx_type* piwork = iwork.fortran_vec ();

      F77_XFCN (dgelsd, DGELSD, (m, n, nrhs, tmp_data, m, pretval, maxmn,
                                 ps, rcon, rank, work.fortran_vec (),
                                 lwork, piwork, info));

      lwork = static_cast<octave_idx_type> (work(0));
      work.resize (dim_vector (lwork, 1));

      F77_XFCN (dgelsd, DGELSD, (m, n, nrhs, tmp_data, m, pretval,
                                 maxmn, ps, rcon, rank,
                                 work.fortran_vec (), lwork,
                                 piwork, info));

      if (rank < minmn)
        {
          if (s.elem (0) == 0.0)
            rcon = 0.0;
          else
            rcon = s.elem (minmn - 1) / s.elem (0);
        }

      retval.resize (n, nrhs);
    }

  return retval;
}

ComplexColumnVector
Matrix::lssolve (const ComplexColumnVector& b) const
{
  ComplexMatrix tmp (*this);
  octave_idx_type info;
  octave_idx_type rank;
  double rcon;
  return tmp.lssolve (b, info, rank, rcon);
}

ComplexColumnVector
Matrix::lssolve (const ComplexColumnVector& b, octave_idx_type& info) const
{
  ComplexMatrix tmp (*this);
  octave_idx_type rank;
  double rcon;
  return tmp.lssolve (b, info, rank, rcon);
}

ComplexColumnVector
Matrix::lssolve (const ComplexColumnVector& b, octave_idx_type& info,
                 octave_idx_type& rank) const
{
  ComplexMatrix tmp (*this);
  double rcon;
  return tmp.lssolve (b, info, rank, rcon);
}

ComplexColumnVector
Matrix::lssolve (const ComplexColumnVector& b, octave_idx_type& info,
                 octave_idx_type& rank, double &rcon) const
{
  ComplexMatrix tmp (*this);
  return tmp.lssolve (b, info, rank, rcon);
}

Matrix&
Matrix::operator += (const DiagMatrix& a)
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  octave_idx_type a_nr = a.rows ();
  octave_idx_type a_nc = a.cols ();

  if (nr != a_nr || nc != a_nc)
    err_nonconformant ("operator +=", nr, nc, a_nr, a_nc);

  for (octave_idx_type i = 0; i < a.length (); i++)
    elem (i, i) += a.elem (i, i);

  return *this;
}

Matrix&
Matrix::operator -= (const DiagMatrix& a)
{
  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  octave_idx_type a_nr = a.rows ();
  octave_idx_type a_nc = a.cols ();

  if (nr != a_nr || nc != a_nc)
    err_nonconformant ("operator -=", nr, nc, a_nr, a_nc);

  for (octave_idx_type i = 0; i < a.length (); i++)
    elem (i, i) -= a.elem (i, i);

  return *this;
}

// unary operations

// column vector by row vector -> matrix operations

Matrix
operator * (const ColumnVector& v, const RowVector& a)
{
  Matrix retval;

  octave_idx_type len = v.numel ();

  if (len != 0)
    {
      octave_idx_type a_len = a.numel ();

      retval = Matrix (len, a_len);
      double *c = retval.fortran_vec ();

      F77_XFCN (dgemm, DGEMM, (F77_CONST_CHAR_ARG2 ("N", 1),
                               F77_CONST_CHAR_ARG2 ("N", 1),
                               len, a_len, 1, 1.0, v.data (), len,
                               a.data (), 1, 0.0, c, len
                               F77_CHAR_ARG_LEN (1)
                               F77_CHAR_ARG_LEN (1)));
    }

  return retval;
}

// other operations.

// FIXME: Do these really belong here?  Maybe they should be in a base class?

boolMatrix
Matrix::all (int dim) const
{
  return NDArray::all (dim);
}

boolMatrix
Matrix::any (int dim) const
{
  return NDArray::any (dim);
}

Matrix
Matrix::cumprod (int dim) const
{
  return NDArray::cumprod (dim);
}

Matrix
Matrix::cumsum (int dim) const
{
  return NDArray::cumsum (dim);
}

Matrix
Matrix::prod (int dim) const
{
  return NDArray::prod (dim);
}

Matrix
Matrix::sum (int dim) const
{
  return NDArray::sum (dim);
}

Matrix
Matrix::sumsq (int dim) const
{
  return NDArray::sumsq (dim);
}

Matrix
Matrix::abs (void) const
{
  return NDArray::abs ();
}

Matrix
Matrix::diag (octave_idx_type k) const
{
  return NDArray::diag (k);
}

DiagMatrix
Matrix::diag (octave_idx_type m, octave_idx_type n) const
{
  DiagMatrix retval;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr == 1 || nc == 1)
    retval = DiagMatrix (*this, m, n);
  else
    (*current_liboctave_error_handler) ("diag: expecting vector argument");

  return retval;
}

ColumnVector
Matrix::row_min (void) const
{
  Array<octave_idx_type> dummy_idx;
  return row_min (dummy_idx);
}

ColumnVector
Matrix::row_min (Array<octave_idx_type>& idx_arg) const
{
  ColumnVector result;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr > 0 && nc > 0)
    {
      result.resize (nr);
      idx_arg.resize (dim_vector (nr, 1));

      for (octave_idx_type i = 0; i < nr; i++)
        {
          octave_idx_type idx_j;

          double tmp_min = octave::numeric_limits<double>::NaN ();

          for (idx_j = 0; idx_j < nc; idx_j++)
            {
              tmp_min = elem (i, idx_j);

              if (! octave::math::isnan (tmp_min))
                break;
            }

          for (octave_idx_type j = idx_j+1; j < nc; j++)
            {
              double tmp = elem (i, j);

              if (octave::math::isnan (tmp))
                continue;
              else if (tmp < tmp_min)
                {
                  idx_j = j;
                  tmp_min = tmp;
                }
            }

          result.elem (i) = tmp_min;
          idx_arg.elem (i) = octave::math::isnan (tmp_min) ? 0 : idx_j;
        }
    }

  return result;
}

ColumnVector
Matrix::row_max (void) const
{
  Array<octave_idx_type> dummy_idx;
  return row_max (dummy_idx);
}

ColumnVector
Matrix::row_max (Array<octave_idx_type>& idx_arg) const
{
  ColumnVector result;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr > 0 && nc > 0)
    {
      result.resize (nr);
      idx_arg.resize (dim_vector (nr, 1));

      for (octave_idx_type i = 0; i < nr; i++)
        {
          octave_idx_type idx_j;

          double tmp_max = octave::numeric_limits<double>::NaN ();

          for (idx_j = 0; idx_j < nc; idx_j++)
            {
              tmp_max = elem (i, idx_j);

              if (! octave::math::isnan (tmp_max))
                break;
            }

          for (octave_idx_type j = idx_j+1; j < nc; j++)
            {
              double tmp = elem (i, j);

              if (octave::math::isnan (tmp))
                continue;
              else if (tmp > tmp_max)
                {
                  idx_j = j;
                  tmp_max = tmp;
                }
            }

          result.elem (i) = tmp_max;
          idx_arg.elem (i) = octave::math::isnan (tmp_max) ? 0 : idx_j;
        }
    }

  return result;
}

RowVector
Matrix::column_min (void) const
{
  Array<octave_idx_type> dummy_idx;
  return column_min (dummy_idx);
}

RowVector
Matrix::column_min (Array<octave_idx_type>& idx_arg) const
{
  RowVector result;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr > 0 && nc > 0)
    {
      result.resize (nc);
      idx_arg.resize (dim_vector (1, nc));

      for (octave_idx_type j = 0; j < nc; j++)
        {
          octave_idx_type idx_i;

          double tmp_min = octave::numeric_limits<double>::NaN ();

          for (idx_i = 0; idx_i < nr; idx_i++)
            {
              tmp_min = elem (idx_i, j);

              if (! octave::math::isnan (tmp_min))
                break;
            }

          for (octave_idx_type i = idx_i+1; i < nr; i++)
            {
              double tmp = elem (i, j);

              if (octave::math::isnan (tmp))
                continue;
              else if (tmp < tmp_min)
                {
                  idx_i = i;
                  tmp_min = tmp;
                }
            }

          result.elem (j) = tmp_min;
          idx_arg.elem (j) = octave::math::isnan (tmp_min) ? 0 : idx_i;
        }
    }

  return result;
}

RowVector
Matrix::column_max (void) const
{
  Array<octave_idx_type> dummy_idx;
  return column_max (dummy_idx);
}

RowVector
Matrix::column_max (Array<octave_idx_type>& idx_arg) const
{
  RowVector result;

  octave_idx_type nr = rows ();
  octave_idx_type nc = cols ();

  if (nr > 0 && nc > 0)
    {
      result.resize (nc);
      idx_arg.resize (dim_vector (1, nc));

      for (octave_idx_type j = 0; j < nc; j++)
        {
          octave_idx_type idx_i;

          double tmp_max = octave::numeric_limits<double>::NaN ();

          for (idx_i = 0; idx_i < nr; idx_i++)
            {
              tmp_max = elem (idx_i, j);

              if (! octave::math::isnan (tmp_max))
                break;
            }

          for (octave_idx_type i = idx_i+1; i < nr; i++)
            {
              double tmp = elem (i, j);

              if (octave::math::isnan (tmp))
                continue;
              else if (tmp > tmp_max)
                {
                  idx_i = i;
                  tmp_max = tmp;
                }
            }

          result.elem (j) = tmp_max;
          idx_arg.elem (j) = octave::math::isnan (tmp_max) ? 0 : idx_i;
        }
    }

  return result;
}

std::ostream&
operator << (std::ostream& os, const Matrix& a)
{
  for (octave_idx_type i = 0; i < a.rows (); i++)
    {
      for (octave_idx_type j = 0; j < a.cols (); j++)
        {
          os << " ";
          octave_write_double (os, a.elem (i, j));
        }
      os << "\n";
    }
  return os;
}

std::istream&
operator >> (std::istream& is, Matrix& a)
{
  octave_idx_type nr = a.rows ();
  octave_idx_type nc = a.cols ();

  if (nr > 0 && nc > 0)
    {
      double tmp;
      for (octave_idx_type i = 0; i < nr; i++)
        for (octave_idx_type j = 0; j < nc; j++)
          {
            tmp = octave_read_value<double> (is);
            if (is)
              a.elem (i, j) = tmp;
            else
              return is;
          }
    }

  return is;
}

Matrix
Givens (double x, double y)
{
  double cc, s, temp_r;

  F77_FUNC (dlartg, DLARTG) (x, y, cc, s, temp_r);

  Matrix g (2, 2);

  g.elem (0, 0) = cc;
  g.elem (1, 1) = cc;
  g.elem (0, 1) = s;
  g.elem (1, 0) = -s;

  return g;
}

Matrix
Sylvester (const Matrix& a, const Matrix& b, const Matrix& c)
{
  Matrix retval;

  // FIXME: need to check that a, b, and c are all the same size.

  // Compute Schur decompositions.

  schur<Matrix> as (a, "U");
  schur<Matrix> bs (b, "U");

  // Transform c to new coordinates.

  Matrix ua = as.unitary_matrix ();
  Matrix sch_a = as.schur_matrix ();

  Matrix ub = bs.unitary_matrix ();
  Matrix sch_b = bs.schur_matrix ();

  Matrix cx = ua.transpose () * c * ub;

  // Solve the sylvester equation, back-transform, and return the solution.

  octave_idx_type a_nr = a.rows ();
  octave_idx_type b_nr = b.rows ();

  double scale;
  octave_idx_type info;

  double *pa = sch_a.fortran_vec ();
  double *pb = sch_b.fortran_vec ();
  double *px = cx.fortran_vec ();

  F77_XFCN (dtrsyl, DTRSYL, (F77_CONST_CHAR_ARG2 ("N", 1),
                             F77_CONST_CHAR_ARG2 ("N", 1),
                             1, a_nr, b_nr, pa, a_nr, pb,
                             b_nr, px, a_nr, scale, info
                             F77_CHAR_ARG_LEN (1)
                             F77_CHAR_ARG_LEN (1)));

  // FIXME: check info?

  retval = ua*cx*ub.transpose ();

  return retval;
}

// matrix by matrix -> matrix operations

/*

## Simple Dot Product, Matrix-Vector and Matrix-Matrix Unit tests
%!assert ([1 2 3] * [ 4 ; 5 ; 6], 32, 1e-14)
%!assert ([1 2 ; 3 4 ] * [5 ; 6], [17 ; 39 ], 1e-14)
%!assert ([1 2 ; 3 4 ] * [5 6 ; 7 8], [19 22; 43 50], 1e-14)

## Test some simple identities
%!shared M, cv, rv, Mt, rvt
%! M = randn (10,10) + 100*eye (10,10);
%! Mt = M';
%! cv = randn (10,1);
%! rv = randn (1,10);
%! rvt = rv';
%!assert ([M*cv,M*cv], M*[cv,cv], 2e-13)
%!assert ([M'*cv,M'*cv], M'*[cv,cv], 2e-13)
%!assert ([rv*M;rv*M], [rv;rv]*M, 2e-13)
%!assert ([rv*M';rv*M'], [rv;rv]*M', 2e-13)
%!assert (2*rv*cv, [rv,rv]*[cv;cv], 2e-13)
%!assert (M'\cv, Mt\cv, 1e-14)
%!assert (M'\rv', Mt\rvt, 1e-14)

*/

static inline char
get_blas_trans_arg (bool trans)
{
  return trans ? 'T' : 'N';
}

// the general GEMM operation

Matrix
xgemm (const Matrix& a, const Matrix& b,
       blas_trans_type transa, blas_trans_type transb)
{
  Matrix retval;

  bool tra = transa != blas_no_trans;
  bool trb = transb != blas_no_trans;

  octave_idx_type a_nr = tra ? a.cols () : a.rows ();
  octave_idx_type a_nc = tra ? a.rows () : a.cols ();

  octave_idx_type b_nr = trb ? b.cols () : b.rows ();
  octave_idx_type b_nc = trb ? b.rows () : b.cols ();

  if (a_nc != b_nr)
    err_nonconformant ("operator *", a_nr, a_nc, b_nr, b_nc);

  if (a_nr == 0 || a_nc == 0 || b_nc == 0)
    retval = Matrix (a_nr, b_nc, 0.0);
  else if (a.data () == b.data () && a_nr == b_nc && tra != trb)
    {
      octave_idx_type lda = a.rows ();

      retval = Matrix (a_nr, b_nc);
      double *c = retval.fortran_vec ();

      const char ctra = get_blas_trans_arg (tra);
      F77_XFCN (dsyrk, DSYRK, (F77_CONST_CHAR_ARG2 ("U", 1),
                               F77_CONST_CHAR_ARG2 (&ctra, 1),
                               a_nr, a_nc, 1.0,
                               a.data (), lda, 0.0, c, a_nr
                               F77_CHAR_ARG_LEN (1)
                               F77_CHAR_ARG_LEN (1)));
      for (int j = 0; j < a_nr; j++)
        for (int i = 0; i < j; i++)
          retval.xelem (j,i) = retval.xelem (i,j);

    }
  else
    {
      octave_idx_type lda = a.rows ();
      octave_idx_type tda = a.cols ();
      octave_idx_type ldb = b.rows ();
      octave_idx_type tdb = b.cols ();

      retval = Matrix (a_nr, b_nc);
      double *c = retval.fortran_vec ();

      if (b_nc == 1)
        {
          if (a_nr == 1)
            F77_FUNC (xddot, XDDOT) (a_nc, a.data (), 1, b.data (), 1, *c);
          else
            {
              const char ctra = get_blas_trans_arg (tra);
              F77_XFCN (dgemv, DGEMV, (F77_CONST_CHAR_ARG2 (&ctra, 1),
                                       lda, tda, 1.0,  a.data (), lda,
                                       b.data (), 1, 0.0, c, 1
                                       F77_CHAR_ARG_LEN (1)));
            }
        }
      else if (a_nr == 1)
        {
          const char crevtrb = get_blas_trans_arg (! trb);
          F77_XFCN (dgemv, DGEMV, (F77_CONST_CHAR_ARG2 (&crevtrb, 1),
                                   ldb, tdb, 1.0,  b.data (), ldb,
                                   a.data (), 1, 0.0, c, 1
                                   F77_CHAR_ARG_LEN (1)));
        }
      else
        {
          const char ctra = get_blas_trans_arg (tra);
          const char ctrb = get_blas_trans_arg (trb);
          F77_XFCN (dgemm, DGEMM, (F77_CONST_CHAR_ARG2 (&ctra, 1),
                                   F77_CONST_CHAR_ARG2 (&ctrb, 1),
                                   a_nr, b_nc, a_nc, 1.0, a.data (),
                                   lda, b.data (), ldb, 0.0, c, a_nr
                                   F77_CHAR_ARG_LEN (1)
                                   F77_CHAR_ARG_LEN (1)));
        }
    }

  return retval;
}

Matrix
operator * (const Matrix& a, const Matrix& b)
{
  return xgemm (a, b);
}

// FIXME: it would be nice to share code among the min/max functions below.

#define EMPTY_RETURN_CHECK(T)                   \
  if (nr == 0 || nc == 0)                       \
    return T (nr, nc);

Matrix
min (double d, const Matrix& m)
{
  octave_idx_type nr = m.rows ();
  octave_idx_type nc = m.columns ();

  EMPTY_RETURN_CHECK (Matrix);

  Matrix result (nr, nc);

  for (octave_idx_type j = 0; j < nc; j++)
    for (octave_idx_type i = 0; i < nr; i++)
      {
        octave_quit ();
        result(i, j) = octave::math::min (d, m(i, j));
      }

  return result;
}

Matrix
min (const Matrix& m, double d)
{
  octave_idx_type nr = m.rows ();
  octave_idx_type nc = m.columns ();

  EMPTY_RETURN_CHECK (Matrix);

  Matrix result (nr, nc);

  for (octave_idx_type j = 0; j < nc; j++)
    for (octave_idx_type i = 0; i < nr; i++)
      {
        octave_quit ();
        result(i, j) = octave::math::min (m(i, j), d);
      }

  return result;
}

Matrix
min (const Matrix& a, const Matrix& b)
{
  octave_idx_type nr = a.rows ();
  octave_idx_type nc = a.columns ();

  if (nr != b.rows () || nc != b.columns ())
    (*current_liboctave_error_handler)
      ("two-arg min requires same size arguments");

  EMPTY_RETURN_CHECK (Matrix);

  Matrix result (nr, nc);

  for (octave_idx_type j = 0; j < nc; j++)
    for (octave_idx_type i = 0; i < nr; i++)
      {
        octave_quit ();
        result(i, j) = octave::math::min (a(i, j), b(i, j));
      }

  return result;
}

Matrix
max (double d, const Matrix& m)
{
  octave_idx_type nr = m.rows ();
  octave_idx_type nc = m.columns ();

  EMPTY_RETURN_CHECK (Matrix);

  Matrix result (nr, nc);

  for (octave_idx_type j = 0; j < nc; j++)
    for (octave_idx_type i = 0; i < nr; i++)
      {
        octave_quit ();
        result(i, j) = octave::math::max (d, m(i, j));
      }

  return result;
}

Matrix
max (const Matrix& m, double d)
{
  octave_idx_type nr = m.rows ();
  octave_idx_type nc = m.columns ();

  EMPTY_RETURN_CHECK (Matrix);

  Matrix result (nr, nc);

  for (octave_idx_type j = 0; j < nc; j++)
    for (octave_idx_type i = 0; i < nr; i++)
      {
        octave_quit ();
        result(i, j) = octave::math::max (m(i, j), d);
      }

  return result;
}

Matrix
max (const Matrix& a, const Matrix& b)
{
  octave_idx_type nr = a.rows ();
  octave_idx_type nc = a.columns ();

  if (nr != b.rows () || nc != b.columns ())
    (*current_liboctave_error_handler)
      ("two-arg max requires same size arguments");

  EMPTY_RETURN_CHECK (Matrix);

  Matrix result (nr, nc);

  for (octave_idx_type j = 0; j < nc; j++)
    for (octave_idx_type i = 0; i < nr; i++)
      {
        octave_quit ();
        result(i, j) = octave::math::max (a(i, j), b(i, j));
      }

  return result;
}

Matrix linspace (const ColumnVector& x1,
                 const ColumnVector& x2,
                 octave_idx_type n)

{
  octave_idx_type m = x1.numel ();

  if (x2.numel () != m)
    (*current_liboctave_error_handler)
      ("linspace: vectors must be of equal length");

  NoAlias<Matrix> retval;

  if (n < 1)
    {
      retval.clear (m, 0);
      return retval;
    }

  retval.clear (m, n);
  for (octave_idx_type i = 0; i < m; i++)
    retval(i, 0) = x1(i);

  // The last column is unused so temporarily store delta there
  double *delta = &retval(0, n-1);
  for (octave_idx_type i = 0; i < m; i++)
    delta[i] = (x2(i) - x1(i)) / (n - 1);

  for (octave_idx_type j = 1; j < n-1; j++)
    for (octave_idx_type i = 0; i < m; i++)
      retval(i, j) = x1(i) + j*delta[i];

  for (octave_idx_type i = 0; i < m; i++)
    retval(i, n-1) = x2(i);

  return retval;
}

MS_CMP_OPS (Matrix, double)
MS_BOOL_OPS (Matrix, double)

SM_CMP_OPS (double, Matrix)
SM_BOOL_OPS (double, Matrix)

MM_CMP_OPS (Matrix, Matrix)
MM_BOOL_OPS (Matrix, Matrix)