////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1998-2024 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 (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include "CSparse.h"
#include "PermMatrix.h"
#include "dSparse.h"
#include "lo-error.h"
#include "lo-mappers.h"
#include "oct-locbuf.h"
#include "oct-sparse.h"
#include "oct-spparms.h"
#include "sparse-lu.h"

OCTAVE_BEGIN_NAMESPACE(octave)

OCTAVE_BEGIN_NAMESPACE(math)

// Wrappers for SuiteSparse (formerly UMFPACK) functions that have
// different names depending on the sparse matrix data type.
//
// All of these functions must be specialized to forward to the correct
// SuiteSparse functions.

template <typename T>
void
umfpack_defaults (double *Control);

template <typename T>
void
umfpack_free_numeric (void **Numeric);

template <typename T>
void
umfpack_free_symbolic (void **Symbolic);

template <typename T>
octave_idx_type
umfpack_get_lunz (octave_idx_type *lnz, octave_idx_type *unz,
                  void *Numeric);

template <typename T>
octave_idx_type
umfpack_get_numeric (octave_idx_type *Lp, octave_idx_type *Lj,
                     T *Lx, // Or Lz_packed
                     octave_idx_type *Up, octave_idx_type *Ui,
                     T *Ux, // Or Uz_packed
                     octave_idx_type *p, octave_idx_type *q,
                     double *Dz_packed, octave_idx_type *do_recip,
                     double *Rs, void *Numeric);

template <typename T>
octave_idx_type
umfpack_numeric (const octave_idx_type *Ap, const octave_idx_type *Ai,
                 const T *Ax, // Or Az_packed
                 void *Symbolic, void **Numeric,
                 const double *Control, double *Info);

template <typename T>
octave_idx_type
umfpack_qsymbolic (octave_idx_type n_row, octave_idx_type n_col,
                   const octave_idx_type *Ap, const octave_idx_type *Ai,
                   const T *Ax, // Or Az_packed
                   const octave_idx_type *Qinit, void **Symbolic,
                   const double *Control, double *Info);

template <typename T>
void
umfpack_report_control (const double *Control);

template <typename T>
void
umfpack_report_info (const double *Control, const double *Info);

template <typename T>
void
umfpack_report_matrix (octave_idx_type n_row, octave_idx_type n_col,
                       const octave_idx_type *Ap,
                       const octave_idx_type *Ai,
                       const T *Ax, // Or Az_packed
                       octave_idx_type col_form, const double *Control);

template <typename T>
void
umfpack_report_numeric (void *Numeric, const double *Control);

template <typename T>
void
umfpack_report_perm (octave_idx_type np, const octave_idx_type *Perm,
                     const double *Control);

template <typename T>
void
umfpack_report_status (double *Control, octave_idx_type status);

template <typename T>
void
umfpack_report_symbolic (void *Symbolic, const double *Control);

#if defined (HAVE_UMFPACK)

// SparseMatrix Specialization.

template <>
inline OCTAVE_API void
umfpack_defaults<double> (double *Control)
{
  UMFPACK_DNAME (defaults) (Control);
}

template <>
inline OCTAVE_API void
umfpack_free_numeric<double> (void **Numeric)
{
  UMFPACK_DNAME (free_numeric) (Numeric);
}

template <>
inline OCTAVE_API void
umfpack_free_symbolic<double> (void **Symbolic)
{
  UMFPACK_DNAME (free_symbolic) (Symbolic);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_get_lunz<double>
(octave_idx_type *lnz, octave_idx_type *unz, void *Numeric)
{
  suitesparse_integer ignore1, ignore2, ignore3;

  return UMFPACK_DNAME (get_lunz) (to_suitesparse_intptr (lnz),
                                   to_suitesparse_intptr (unz),
                                   &ignore1, &ignore2, &ignore3, Numeric);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_get_numeric<double>
(octave_idx_type *Lp, octave_idx_type *Lj, double *Lx,
 octave_idx_type *Up, octave_idx_type *Ui, double *Ux,
 octave_idx_type *p, octave_idx_type *q, double *Dx,
 octave_idx_type *do_recip, double *Rs, void *Numeric)
{
  return UMFPACK_DNAME (get_numeric) (to_suitesparse_intptr (Lp),
                                      to_suitesparse_intptr (Lj),
                                      Lx, to_suitesparse_intptr (Up),
                                      to_suitesparse_intptr (Ui), Ux,
                                      to_suitesparse_intptr (p),
                                      to_suitesparse_intptr (q), Dx,
                                      to_suitesparse_intptr (do_recip),
                                      Rs, Numeric);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_numeric<double>
(const octave_idx_type *Ap, const octave_idx_type *Ai,
 const double *Ax, void *Symbolic, void **Numeric,
 const double *Control, double *Info)
{
  return UMFPACK_DNAME (numeric) (to_suitesparse_intptr (Ap),
                                  to_suitesparse_intptr (Ai),
                                  Ax, Symbolic, Numeric, Control, Info);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_qsymbolic<double>
(octave_idx_type n_row, octave_idx_type n_col, const octave_idx_type *Ap,
 const octave_idx_type *Ai, const double *Ax,
 const octave_idx_type *Qinit, void **Symbolic,
 const double *Control, double *Info)
{
  return UMFPACK_DNAME (qsymbolic) (n_row, n_col,
                                    to_suitesparse_intptr (Ap),
                                    to_suitesparse_intptr (Ai), Ax,
                                    to_suitesparse_intptr (Qinit),
                                    Symbolic, Control, Info);
}

template <>
inline OCTAVE_API void
umfpack_report_control<double> (const double *Control)
{
  UMFPACK_DNAME (report_control) (Control);
}

template <>
inline OCTAVE_API void
umfpack_report_info<double> (const double *Control, const double *Info)
{
  UMFPACK_DNAME (report_info) (Control, Info);
}

template <>
inline OCTAVE_API void
umfpack_report_matrix<double>
(octave_idx_type n_row, octave_idx_type n_col, const octave_idx_type *Ap,
 const octave_idx_type *Ai, const double *Ax, octave_idx_type col_form,
 const double *Control)
{
  UMFPACK_DNAME (report_matrix) (n_row, n_col,
                                 to_suitesparse_intptr (Ap),
                                 to_suitesparse_intptr (Ai), Ax,
                                 col_form, Control);
}

template <>
inline OCTAVE_API void
umfpack_report_numeric<double> (void *Numeric, const double *Control)
{
  UMFPACK_DNAME (report_numeric) (Numeric, Control);
}

template <>
inline OCTAVE_API void
umfpack_report_perm<double>
(octave_idx_type np, const octave_idx_type *Perm, const double *Control)
{
  UMFPACK_DNAME (report_perm) (np, to_suitesparse_intptr (Perm), Control);
}

template <>
inline OCTAVE_API void
umfpack_report_status<double> (double *Control, octave_idx_type status)
{
  UMFPACK_DNAME (report_status) (Control, status);
}

template <>
inline OCTAVE_API void
umfpack_report_symbolic<double> (void *Symbolic, const double *Control)
{
  UMFPACK_DNAME (report_symbolic) (Symbolic, Control);
}

// SparseComplexMatrix specialization.

template <>
inline OCTAVE_API void
umfpack_defaults<Complex> (double *Control)
{
  UMFPACK_ZNAME (defaults) (Control);
}

template <>
inline OCTAVE_API void
umfpack_free_numeric<Complex> (void **Numeric)
{
  UMFPACK_ZNAME (free_numeric) (Numeric);
}

template <>
inline OCTAVE_API void
umfpack_free_symbolic<Complex> (void **Symbolic)
{
  UMFPACK_ZNAME (free_symbolic) (Symbolic);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_get_lunz<Complex>
(octave_idx_type *lnz, octave_idx_type *unz, void *Numeric)
{
  suitesparse_integer ignore1, ignore2, ignore3;

  return UMFPACK_ZNAME (get_lunz) (to_suitesparse_intptr (lnz),
                                   to_suitesparse_intptr (unz),
                                   &ignore1, &ignore2, &ignore3, Numeric);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_get_numeric<Complex>
(octave_idx_type *Lp, octave_idx_type *Lj, Complex *Lz,
 octave_idx_type *Up, octave_idx_type *Ui, Complex *Uz,
 octave_idx_type *p, octave_idx_type *q, double *Dz,
 octave_idx_type *do_recip, double *Rs, void *Numeric)
{
  return UMFPACK_ZNAME (get_numeric) (to_suitesparse_intptr (Lp),
                                      to_suitesparse_intptr (Lj),
                                      reinterpret_cast<double *> (Lz),
                                      nullptr, to_suitesparse_intptr (Up),
                                      to_suitesparse_intptr (Ui),
                                      reinterpret_cast<double *> (Uz),
                                      nullptr, to_suitesparse_intptr (p),
                                      to_suitesparse_intptr (q),
                                      reinterpret_cast<double *> (Dz),
                                      nullptr, to_suitesparse_intptr (do_recip),
                                      Rs, Numeric);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_numeric<Complex>
(const octave_idx_type *Ap, const octave_idx_type *Ai,
 const Complex *Az, void *Symbolic, void **Numeric,
 const double *Control, double *Info)
{
  return UMFPACK_ZNAME (numeric) (to_suitesparse_intptr (Ap),
                                  to_suitesparse_intptr (Ai),
                                  reinterpret_cast<const double *> (Az),
                                  nullptr, Symbolic, Numeric, Control, Info);
}

template <>
inline OCTAVE_API octave_idx_type
umfpack_qsymbolic<Complex>
(octave_idx_type n_row, octave_idx_type n_col,
 const octave_idx_type *Ap, const octave_idx_type *Ai,
 const Complex *Az, const octave_idx_type *Qinit,
 void **Symbolic, const double *Control, double *Info)
{
  return UMFPACK_ZNAME (qsymbolic) (n_row, n_col,
                                    to_suitesparse_intptr (Ap),
                                    to_suitesparse_intptr (Ai),
                                    reinterpret_cast<const double *> (Az),
                                    nullptr, to_suitesparse_intptr (Qinit),
                                    Symbolic, Control, Info);
}

template <>
inline OCTAVE_API void
umfpack_report_control<Complex> (const double *Control)
{
  UMFPACK_ZNAME (report_control) (Control);
}

template <>
inline OCTAVE_API void
umfpack_report_info<Complex> (const double *Control, const double *Info)
{
  UMFPACK_ZNAME (report_info) (Control, Info);
}

template <>
inline OCTAVE_API void
umfpack_report_matrix<Complex>
(octave_idx_type n_row, octave_idx_type n_col,
 const octave_idx_type *Ap, const octave_idx_type *Ai,
 const Complex *Az, octave_idx_type col_form, const double *Control)
{
  UMFPACK_ZNAME (report_matrix) (n_row, n_col,
                                 to_suitesparse_intptr (Ap),
                                 to_suitesparse_intptr (Ai),
                                 reinterpret_cast<const double *> (Az),
                                 nullptr, col_form, Control);
}

template <>
inline OCTAVE_API void
umfpack_report_numeric<Complex> (void *Numeric, const double *Control)
{
  UMFPACK_ZNAME (report_numeric) (Numeric, Control);
}

template <>
inline OCTAVE_API void
umfpack_report_perm<Complex>
(octave_idx_type np, const octave_idx_type *Perm, const double *Control)
{
  UMFPACK_ZNAME (report_perm) (np, to_suitesparse_intptr (Perm), Control);
}

template <>
inline OCTAVE_API void
umfpack_report_status<Complex> (double *Control, octave_idx_type status)
{
  UMFPACK_ZNAME (report_status) (Control, status);
}

template <>
inline OCTAVE_API void
umfpack_report_symbolic <Complex> (void *Symbolic, const double *Control)
{
  UMFPACK_ZNAME (report_symbolic) (Symbolic, Control);
}

#endif

template <typename lu_type>
sparse_lu<lu_type>::sparse_lu (const lu_type& a, const Matrix& piv_thres,
                               bool scale)
  : m_L (), m_U (), m_R (), m_cond (0), m_P (), m_Q ()
{
#if defined (HAVE_UMFPACK)
  octave_idx_type nr = a.rows ();
  octave_idx_type nc = a.cols ();

  // Setup the control parameters
  Matrix Control (UMFPACK_CONTROL, 1);
  double *control = Control.rwdata ();
  umfpack_defaults<lu_elt_type> (control);

  double tmp = sparse_params::get_key ("spumoni");
  if (! math::isnan (tmp))
    Control (UMFPACK_PRL) = tmp;

  if (piv_thres.numel () == 2)
    {
      tmp = (piv_thres (0) > 1. ? 1. : piv_thres (0));
      if (! math::isnan (tmp))
        Control (UMFPACK_PIVOT_TOLERANCE) = tmp;

      tmp = (piv_thres (1) > 1. ? 1. : piv_thres (1));
      if (! math::isnan (tmp))
        Control (UMFPACK_SYM_PIVOT_TOLERANCE) = tmp;
    }
  else
    {
      tmp = sparse_params::get_key ("piv_tol");
      if (! math::isnan (tmp))
        Control (UMFPACK_PIVOT_TOLERANCE) = tmp;

      tmp = sparse_params::get_key ("sym_tol");
      if (! math::isnan (tmp))
        Control (UMFPACK_SYM_PIVOT_TOLERANCE) = tmp;
    }

  // Set whether we are allowed to modify Q or not
  tmp = sparse_params::get_key ("autoamd");
  if (! math::isnan (tmp))
    Control (UMFPACK_FIXQ) = tmp;

  // Turn-off UMFPACK scaling for LU
  if (scale)
    Control (UMFPACK_SCALE) = UMFPACK_SCALE_SUM;
  else
    Control (UMFPACK_SCALE) = UMFPACK_SCALE_NONE;

  umfpack_report_control<lu_elt_type> (control);

  const octave_idx_type *Ap = a.cidx ();
  const octave_idx_type *Ai = a.ridx ();
  const lu_elt_type *Ax = a.data ();

  umfpack_report_matrix<lu_elt_type> (nr, nc, Ap, Ai, Ax,
                                      static_cast<octave_idx_type> (1),
                                      control);

  void *Symbolic;
  Matrix Info (1, UMFPACK_INFO);
  double *info = Info.rwdata ();
  int status = umfpack_qsymbolic<lu_elt_type> (nr, nc, Ap, Ai, Ax, nullptr,
               &Symbolic, control, info);

  if (status < 0)
    {
      umfpack_report_status<lu_elt_type> (control, status);
      umfpack_report_info<lu_elt_type> (control, info);

      umfpack_free_symbolic<lu_elt_type> (&Symbolic);

      (*current_liboctave_error_handler)
        ("sparse_lu: symbolic factorization failed");
    }
  else
    {
      umfpack_report_symbolic<lu_elt_type> (Symbolic, control);

      void *Numeric;
      status = umfpack_numeric<lu_elt_type> (Ap, Ai, Ax, Symbolic,
                                             &Numeric, control, info);
      umfpack_free_symbolic<lu_elt_type> (&Symbolic);

      m_cond = Info (UMFPACK_RCOND);

      if (status < 0)
        {
          umfpack_report_status<lu_elt_type> (control, status);
          umfpack_report_info<lu_elt_type> (control, info);

          umfpack_free_numeric<lu_elt_type> (&Numeric);

          (*current_liboctave_error_handler)
            ("sparse_lu: numeric factorization failed");
        }
      else
        {
          umfpack_report_numeric<lu_elt_type> (Numeric, control);

          octave_idx_type lnz, unz;
          status = umfpack_get_lunz<lu_elt_type> (&lnz, &unz, Numeric);

          if (status < 0)
            {
              umfpack_report_status<lu_elt_type> (control, status);
              umfpack_report_info<lu_elt_type> (control, info);

              umfpack_free_numeric<lu_elt_type> (&Numeric);

              (*current_liboctave_error_handler)
                ("sparse_lu: extracting LU factors failed");
            }
          else
            {
              octave_idx_type n_inner = (nr < nc ? nr : nc);

              if (lnz < 1)
                m_L = lu_type (n_inner, nr,
                               static_cast<octave_idx_type> (1));
              else
                m_L = lu_type (n_inner, nr, lnz);

              octave_idx_type *Ltp = m_L.cidx ();
              octave_idx_type *Ltj = m_L.ridx ();
              lu_elt_type *Ltx = m_L.data ();

              if (unz < 1)
                m_U = lu_type (n_inner, nc,
                               static_cast<octave_idx_type> (1));
              else
                m_U = lu_type (n_inner, nc, unz);

              octave_idx_type *Up = m_U.cidx ();
              octave_idx_type *Uj = m_U.ridx ();
              lu_elt_type *Ux = m_U.data ();

              m_R = SparseMatrix (nr, nr, nr);
              for (octave_idx_type i = 0; i < nr; i++)
                {
                  m_R.xridx (i) = i;
                  m_R.xcidx (i) = i;
                }
              m_R.xcidx (nr) = nr;
              double *Rx = m_R.data ();

              m_P.resize (dim_vector (nr, 1));
              octave_idx_type *p = m_P.rwdata ();

              m_Q.resize (dim_vector (nc, 1));
              octave_idx_type *q = m_Q.rwdata ();

              octave_idx_type do_recip;
              status = umfpack_get_numeric<lu_elt_type> (Ltp, Ltj, Ltx,
                       Up, Uj, Ux,
                       p, q, nullptr,
                       &do_recip, Rx,
                       Numeric);

              umfpack_free_numeric<lu_elt_type> (&Numeric);

              if (status < 0)
                {
                  umfpack_report_status<lu_elt_type> (control, status);

                  (*current_liboctave_error_handler)
                    ("sparse_lu: extracting LU factors failed");
                }
              else
                {
                  m_L = m_L.transpose ();

                  if (do_recip)
                    for (octave_idx_type i = 0; i < nr; i++)
                      Rx[i] = 1.0 / Rx[i];

                  umfpack_report_matrix<lu_elt_type> (nr, n_inner,
                                                      m_L.cidx (),
                                                      m_L.ridx (),
                                                      m_L.data (),
                                                      static_cast<octave_idx_type> (1),
                                                      control);
                  umfpack_report_matrix<lu_elt_type> (n_inner, nc,
                                                      m_U.cidx (),
                                                      m_U.ridx (),
                                                      m_U.data (),
                                                      static_cast<octave_idx_type> (1),
                                                      control);
                  umfpack_report_perm<lu_elt_type> (nr, p, control);
                  umfpack_report_perm<lu_elt_type> (nc, q, control);
                }

              umfpack_report_info<lu_elt_type> (control, info);
            }
        }
    }

#else

  octave_unused_parameter (a);
  octave_unused_parameter (piv_thres);
  octave_unused_parameter (scale);

  (*current_liboctave_error_handler)
    ("support for UMFPACK was unavailable or disabled when liboctave was built");

#endif
}

template <typename lu_type>
sparse_lu<lu_type>::sparse_lu (const lu_type& a,
                               const ColumnVector& Qinit,
                               const Matrix& piv_thres, bool scale,
                               bool FixedQ, double droptol,
                               bool milu, bool udiag)
  : m_L (), m_U (), m_R (), m_cond (0), m_P (), m_Q ()
{
#if defined (HAVE_UMFPACK)

  if (milu)
    (*current_liboctave_error_handler)
      ("Modified incomplete LU not implemented");

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

  // Setup the control parameters
  Matrix Control (UMFPACK_CONTROL, 1);
  double *control = Control.rwdata ();
  umfpack_defaults<lu_elt_type> (control);

  double tmp = sparse_params::get_key ("spumoni");
  if (! math::isnan (tmp))
    Control (UMFPACK_PRL) = tmp;

  if (piv_thres.numel () == 2)
    {
      tmp = (piv_thres (0) > 1. ? 1. : piv_thres (0));
      if (! math::isnan (tmp))
        Control (UMFPACK_PIVOT_TOLERANCE) = tmp;
      tmp = (piv_thres (1) > 1. ? 1. : piv_thres (1));
      if (! math::isnan (tmp))
        Control (UMFPACK_SYM_PIVOT_TOLERANCE) = tmp;
    }
  else
    {
      tmp = sparse_params::get_key ("piv_tol");
      if (! math::isnan (tmp))
        Control (UMFPACK_PIVOT_TOLERANCE) = tmp;

      tmp = sparse_params::get_key ("sym_tol");
      if (! math::isnan (tmp))
        Control (UMFPACK_SYM_PIVOT_TOLERANCE) = tmp;
    }

  if (droptol >= 0.)
    Control (UMFPACK_DROPTOL) = droptol;

  // Set whether we are allowed to modify Q or not
  if (FixedQ)
    Control (UMFPACK_FIXQ) = 1.0;
  else
    {
      tmp = sparse_params::get_key ("autoamd");
      if (! math::isnan (tmp))
        Control (UMFPACK_FIXQ) = tmp;
    }

  // Turn-off UMFPACK scaling for LU
  if (scale)
    Control (UMFPACK_SCALE) = UMFPACK_SCALE_SUM;
  else
    Control (UMFPACK_SCALE) = UMFPACK_SCALE_NONE;

  umfpack_report_control<lu_elt_type> (control);

  const octave_idx_type *Ap = a.cidx ();
  const octave_idx_type *Ai = a.ridx ();
  const lu_elt_type *Ax = a.data ();

  umfpack_report_matrix<lu_elt_type> (nr, nc, Ap, Ai, Ax,
                                      static_cast<octave_idx_type> (1),
                                      control);

  void *Symbolic;
  Matrix Info (1, UMFPACK_INFO);
  double *info = Info.rwdata ();
  int status;

  // Null loop so that qinit is immediately deallocated when not needed
  do
    {
      OCTAVE_LOCAL_BUFFER (octave_idx_type, qinit, nc);

      for (octave_idx_type i = 0; i < nc; i++)
        qinit[i] = static_cast<octave_idx_type> (Qinit (i));

      status = umfpack_qsymbolic<lu_elt_type> (nr, nc, Ap, Ai, Ax,
               qinit, &Symbolic, control,
               info);
    }
  while (0);

  if (status < 0)
    {
      umfpack_report_status<lu_elt_type> (control, status);
      umfpack_report_info<lu_elt_type> (control, info);

      umfpack_free_symbolic<lu_elt_type> (&Symbolic);

      (*current_liboctave_error_handler)
        ("sparse_lu: symbolic factorization failed");
    }
  else
    {
      umfpack_report_symbolic<lu_elt_type> (Symbolic, control);

      void *Numeric;
      status = umfpack_numeric<lu_elt_type> (Ap, Ai, Ax, Symbolic,
                                             &Numeric, control, info);
      umfpack_free_symbolic<lu_elt_type> (&Symbolic);

      m_cond = Info (UMFPACK_RCOND);

      if (status < 0)
        {
          umfpack_report_status<lu_elt_type> (control, status);
          umfpack_report_info<lu_elt_type> (control, info);

          umfpack_free_numeric<lu_elt_type> (&Numeric);

          (*current_liboctave_error_handler)
            ("sparse_lu: numeric factorization failed");
        }
      else
        {
          umfpack_report_numeric<lu_elt_type> (Numeric, control);

          octave_idx_type lnz, unz;
          status = umfpack_get_lunz<lu_elt_type> (&lnz, &unz, Numeric);

          if (status < 0)
            {
              umfpack_report_status<lu_elt_type> (control, status);
              umfpack_report_info<lu_elt_type> (control, info);

              umfpack_free_numeric<lu_elt_type> (&Numeric);

              (*current_liboctave_error_handler)
                ("sparse_lu: extracting LU factors failed");
            }
          else
            {
              octave_idx_type n_inner = (nr < nc ? nr : nc);

              if (lnz < 1)
                m_L = lu_type (n_inner, nr,
                               static_cast<octave_idx_type> (1));
              else
                m_L = lu_type (n_inner, nr, lnz);

              octave_idx_type *Ltp = m_L.cidx ();
              octave_idx_type *Ltj = m_L.ridx ();
              lu_elt_type *Ltx = m_L.data ();

              if (unz < 1)
                m_U = lu_type (n_inner, nc,
                               static_cast<octave_idx_type> (1));
              else
                m_U = lu_type (n_inner, nc, unz);

              octave_idx_type *Up = m_U.cidx ();
              octave_idx_type *Uj = m_U.ridx ();
              lu_elt_type *Ux = m_U.data ();

              m_R = SparseMatrix (nr, nr, nr);
              for (octave_idx_type i = 0; i < nr; i++)
                {
                  m_R.xridx (i) = i;
                  m_R.xcidx (i) = i;
                }
              m_R.xcidx (nr) = nr;
              double *Rx = m_R.data ();

              m_P.resize (dim_vector (nr, 1));
              octave_idx_type *p = m_P.rwdata ();

              m_Q.resize (dim_vector (nc, 1));
              octave_idx_type *q = m_Q.rwdata ();

              octave_idx_type do_recip;
              status = umfpack_get_numeric<lu_elt_type> (Ltp, Ltj, Ltx,
                       Up, Uj, Ux,
                       p, q, nullptr,
                       &do_recip,
                       Rx, Numeric);

              umfpack_free_numeric<lu_elt_type> (&Numeric);

              if (status < 0)
                {
                  umfpack_report_status<lu_elt_type> (control, status);

                  (*current_liboctave_error_handler)
                    ("sparse_lu: extracting LU factors failed");
                }
              else
                {
                  m_L = m_L.transpose ();

                  if (do_recip)
                    for (octave_idx_type i = 0; i < nr; i++)
                      Rx[i] = 1.0 / Rx[i];

                  umfpack_report_matrix<lu_elt_type> (nr, n_inner,
                                                      m_L.cidx (),
                                                      m_L.ridx (),
                                                      m_L.data (),
                                                      static_cast<octave_idx_type> (1),
                                                      control);
                  umfpack_report_matrix<lu_elt_type> (n_inner, nc,
                                                      m_U.cidx (),
                                                      m_U.ridx (),
                                                      m_U.data (),
                                                      static_cast<octave_idx_type> (1),
                                                      control);
                  umfpack_report_perm<lu_elt_type> (nr, p, control);
                  umfpack_report_perm<lu_elt_type> (nc, q, control);
                }

              umfpack_report_info<lu_elt_type> (control, info);
            }
        }
    }

  if (udiag)
    (*current_liboctave_error_handler)
      ("Option udiag of incomplete LU not implemented");

#else

  octave_unused_parameter (a);
  octave_unused_parameter (Qinit);
  octave_unused_parameter (piv_thres);
  octave_unused_parameter (scale);
  octave_unused_parameter (FixedQ);
  octave_unused_parameter (droptol);
  octave_unused_parameter (milu);
  octave_unused_parameter (udiag);

  (*current_liboctave_error_handler)
    ("support for UMFPACK was unavailable or disabled when liboctave was built");

#endif
}

template <typename lu_type>
lu_type
sparse_lu<lu_type>::Y () const
{
  octave_idx_type nr = m_L.rows ();
  octave_idx_type nz = m_L.cols ();
  octave_idx_type nc = m_U.cols ();

  lu_type Yout (nr, nc, m_L.nnz () + m_U.nnz () - (nr<nz?nr:nz));
  octave_idx_type ii = 0;
  Yout.xcidx (0) = 0;

  for (octave_idx_type j = 0; j < nc; j++)
    {
      for (octave_idx_type i = m_U.cidx (j); i < m_U.cidx (j + 1); i++)
        {
          Yout.xridx (ii) = m_U.ridx (i);
          Yout.xdata (ii++) = m_U.data (i);
        }

      if (j < nz)
        {
          // Note the +1 skips the 1.0 on the diagonal
          for (octave_idx_type i = m_L.cidx (j) + 1;
               i < m_L.cidx (j +1); i++)
            {
              Yout.xridx (ii) = m_L.ridx (i);
              Yout.xdata (ii++) = m_L.data (i);
            }
        }

      Yout.xcidx (j + 1) = ii;
    }

  return Yout;
}

template <typename lu_type>
SparseMatrix
sparse_lu<lu_type>::Pr () const
{
  octave_idx_type nr = m_L.rows ();

  SparseMatrix Pout (nr, nr, nr);

  for (octave_idx_type i = 0; i < nr; i++)
    {
      Pout.cidx (i) = i;
      Pout.ridx (m_P(i)) = i;
      Pout.data (i) = 1;
    }

  Pout.cidx (nr) = nr;

  return Pout;
}

template <typename lu_type>
ColumnVector
sparse_lu<lu_type>::Pr_vec () const
{
  octave_idx_type nr = m_L.rows ();

  ColumnVector Pout (nr);

  for (octave_idx_type i = 0; i < nr; i++)
    Pout.xelem (i) = static_cast<double> (m_P(i) + 1);

  return Pout;
}

template <typename lu_type>
PermMatrix
sparse_lu<lu_type>::Pr_mat () const
{
  return PermMatrix (m_P, false);
}

template <typename lu_type>
SparseMatrix
sparse_lu<lu_type>::Pc () const
{
  octave_idx_type nc = m_U.cols ();

  SparseMatrix Pout (nc, nc, nc);

  for (octave_idx_type i = 0; i < nc; i++)
    {
      Pout.cidx (i) = i;
      Pout.ridx (i) = m_Q(i);
      Pout.data (i) = 1;
    }

  Pout.cidx (nc) = nc;

  return Pout;
}

template <typename lu_type>
ColumnVector
sparse_lu<lu_type>::Pc_vec () const
{
  octave_idx_type nc = m_U.cols ();

  ColumnVector Pout (nc);

  for (octave_idx_type i = 0; i < nc; i++)
    Pout.xelem (i) = static_cast<double> (m_Q(i) + 1);

  return Pout;
}

template <typename lu_type>
PermMatrix
sparse_lu<lu_type>::Pc_mat () const
{
  return PermMatrix (m_Q, true);
}

// Instantiations we need.
template class OCTAVE_API sparse_lu<SparseMatrix>;

template class OCTAVE_API sparse_lu<SparseComplexMatrix>;

OCTAVE_END_NAMESPACE(math)
OCTAVE_END_NAMESPACE(octave)