view liboctave/numeric/gsvd.cc @ 27918:b442ec6dda5c

use centralized file for copyright info for individual contributors * COPYRIGHT.md: New file. * In most other files, use "Copyright (C) YYYY-YYYY The Octave Project Developers" instead of tracking individual names in separate source files. The motivation is to reduce the effort required to update the notices each year. Until now, the Octave source files contained copyright notices that list individual contributors. I adopted these file-scope copyright notices because that is what everyone was doing 30 years ago in the days before distributed version control systems. But now, with many contributors and modern version control systems, having these file-scope copyright notices causes trouble when we update copyright years or refactor code. Over time, the file-scope copyright notices may become outdated as new contributions are made or code is moved from one file to another. Sometimes people contribute significant patches but do not add a line claiming copyright. Other times, people add a copyright notice for their contribution but then a later refactoring moves part or all of their contribution to another file and the notice is not moved with the code. As a practical matter, moving such notices is difficult -- determining what parts are due to a particular contributor requires a time-consuming search through the project history. Even managing the yearly update of copyright years is problematic. We have some contributors who are no longer living. Should we update the copyright dates for their contributions when we release new versions? Probably not, but we do still want to claim copyright for the project as a whole. To minimize the difficulty of maintaining the copyright notices, I would like to change Octave's sources to use what is described here: https://softwarefreedom.org/resources/2012/ManagingCopyrightInformation.html in the section "Maintaining centralized copyright notices": The centralized notice approach consolidates all copyright notices in a single location, usually a top-level file. This file should contain all of the copyright notices provided project contributors, unless the contribution was clearly insignificant. It may also credit -- without a copyright notice -- anyone who helped with the project but did not contribute code or other copyrighted material. This approach captures less information about contributions within individual files, recognizing that the DVCS is better equipped to record those details. As we mentioned before, it does have one disadvantage as compared to the file-scope approach: if a single file is separated from the distribution, the recipient won't see the contributors' copyright notices. But this can be easily remedied by including a single copyright notice in each file's header, pointing to the top-level file: Copyright YYYY-YYYY The Octave Project Developers See the COPYRIGHT file at the top-level directory of this distribution or at https://octave.org/COPYRIGHT.html. followed by the usual GPL copyright statement. For more background, see the discussion here: https://lists.gnu.org/archive/html/octave-maintainers/2020-01/msg00009.html Most files in the following directories have been skipped intentinally in this changeset: doc libgui/qterminal liboctave/external m4
author John W. Eaton <jwe@octave.org>
date Mon, 06 Jan 2020 15:38:17 -0500
parents 84ff9953faa1
children 1891570abac8
line wrap: on
line source

/*

Copyright (C) 1997-2019 The Octave Project Developers

See the file COPYRIGHT.md in the top-level directory of this distribution
or <https://octave.org/COPYRIGHT.html/>.


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/>.

*/

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <vector>

#include "CMatrix.h"
#include "dDiagMatrix.h"
#include "dMatrix.h"
#include "fCMatrix.h"
#include "fDiagMatrix.h"
#include "fMatrix.h"
#include "gsvd.h"
#include "lo-error.h"
#include "lo-lapack-proto.h"
#include "oct-shlib.h"

namespace octave
{
  static std::map<std::string, void *> gsvd_fcn;

  static bool have_DGGSVD3 = false;
  static bool gsvd_initialized = false;

  /* Hack to stringize macro results. */
#define xSTRINGIZE(x) #x
#define STRINGIZE(x) xSTRINGIZE(x)

  static void initialize_gsvd (void)
  {
    if (gsvd_initialized)
      return;

    dynamic_library libs ("");
    if (! libs)
      {
        // FIXME: Should we throw an error if we cannot check the libraries?
        have_DGGSVD3 = false;
        return;
      }

    have_DGGSVD3 = (libs.search (STRINGIZE (F77_FUNC (dggsvd3, DGGSVD3)))
                    != nullptr);

    if (have_DGGSVD3)
      {
        gsvd_fcn["dg"] = libs.search (STRINGIZE (F77_FUNC (dggsvd3, DGGSVD3)));
        gsvd_fcn["sg"] = libs.search (STRINGIZE (F77_FUNC (sggsvd3, SGGSVD3)));
        gsvd_fcn["zg"] = libs.search (STRINGIZE (F77_FUNC (zggsvd3, ZGGSVD3)));
        gsvd_fcn["cg"] = libs.search (STRINGIZE (F77_FUNC (cggsvd3, CGGSVD3)));
      }
    else
      {
        gsvd_fcn["dg"] = libs.search (STRINGIZE (F77_FUNC (dggsvd, DGGSVD)));
        gsvd_fcn["sg"] = libs.search (STRINGIZE (F77_FUNC (sggsvd, SGGSVD)));
        gsvd_fcn["zg"] = libs.search (STRINGIZE (F77_FUNC (zggsvd, ZGGSVD)));
        gsvd_fcn["cg"] = libs.search (STRINGIZE (F77_FUNC (cggsvd, CGGSVD)));
      }
    gsvd_initialized = true;
  }

  template<class T1>
  struct real_ggsvd_ptr
  {
    typedef F77_RET_T (*type)
    (F77_CONST_CHAR_ARG_DECL,   // JOBU
     F77_CONST_CHAR_ARG_DECL,   // JOBV
     F77_CONST_CHAR_ARG_DECL,   // JOBQ
     const F77_INT&,            // M
     const F77_INT&,            // N
     const F77_INT&,            // P
     F77_INT &,                 // K
     F77_INT &,                 // L
     T1*,                       // A(LDA,N)
     const F77_INT&,            // LDA
     T1*,                       // B(LDB,N)
     const F77_INT&,            // LDB
     T1*,                       // ALPHA(N)
     T1*,                       // BETA(N)
     T1*,                       // U(LDU,M)
     const F77_INT&,            // LDU
     T1*,                       // V(LDV,P)
     const F77_INT&,            // LDV
     T1*,                       // Q(LDQ,N)
     const F77_INT&,            // LDQ
     T1*,                       // WORK
     F77_INT*,                  // IWORK(N)
     F77_INT&                   // INFO
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL);
  };

  template<class T1>
  struct real_ggsvd3_ptr
  {
    typedef F77_RET_T (*type)
    (F77_CONST_CHAR_ARG_DECL,   // JOBU
     F77_CONST_CHAR_ARG_DECL,   // JOBV
     F77_CONST_CHAR_ARG_DECL,   // JOBQ
     const F77_INT&,            // M
     const F77_INT&,            // N
     const F77_INT&,            // P
     F77_INT &,                 // K
     F77_INT &,                 // L
     T1*,                       // A(LDA,N)
     const F77_INT&,            // LDA
     T1*,                       // B(LDB,N)
     const F77_INT&,            // LDB
     T1*,                       // ALPHA(N)
     T1*,                       // BETA(N)
     T1*,                       // U(LDU,M)
     const F77_INT&,            // LDU
     T1*,                       // V(LDV,P)
     const F77_INT&,            // LDV
     T1*,                       // Q(LDQ,N)
     const F77_INT&,            // LDQ
     T1*,                       // WORK
     const F77_INT&,            // LWORK
     F77_INT*,                  // IWORK(N)
     F77_INT&                   // INFO
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL);
  };

  template<class T1, class T2>
  struct comp_ggsvd_ptr
  {
    typedef F77_RET_T (*type)
    (F77_CONST_CHAR_ARG_DECL,   // JOBU
     F77_CONST_CHAR_ARG_DECL,   // JOBV
     F77_CONST_CHAR_ARG_DECL,   // JOBQ
     const F77_INT&,            // M
     const F77_INT&,            // N
     const F77_INT&,            // P
     F77_INT &,                 // K
     F77_INT &,                 // L
     T1*,                       // A(LDA,N)
     const F77_INT&,            // LDA
     T1*,                       // B(LDB,N)
     const F77_INT&,            // LDB
     T2*,                       // ALPHA(N)
     T2*,                       // BETA(N)
     T1*,                       // U(LDU,M)
     const F77_INT&,            // LDU
     T1*,                       // V(LDV,P)
     const F77_INT&,            // LDV
     T1*,                       // Q(LDQ,N)
     const F77_INT&,            // LDQ
     T1*,                       // WORK
     T2*,                       // RWORK
     F77_INT*,                  // IWORK(N)
     F77_INT&                   // INFO
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL);
  };

  template<class T1, class T2>
  struct comp_ggsvd3_ptr
  {
    typedef F77_RET_T (*type)
    (F77_CONST_CHAR_ARG_DECL,   // JOBU
     F77_CONST_CHAR_ARG_DECL,   // JOBV
     F77_CONST_CHAR_ARG_DECL,   // JOBQ
     const F77_INT&,            // M
     const F77_INT&,            // N
     const F77_INT&,            // P
     F77_INT &,                 // K
     F77_INT &,                 // L
     T1*,                       // A(LDA,N)
     const F77_INT&,            // LDA
     T1*,                       // B(LDB,N)
     const F77_INT&,            // LDB
     T2*,                       // ALPHA(N)
     T2*,                       // BETA(N)
     T1*,                       // U(LDU,M)
     const F77_INT&,            // LDU
     T1*,                       // V(LDV,P)
     const F77_INT&,            // LDV
     T1*,                       // Q(LDQ,N)
     const F77_INT&,            // LDQ
     T1*,                       // WORK
     const F77_INT&,            // LWORK
     T2*,                       // RWORK
     F77_INT*,                  // IWORK(N)
     F77_INT&                   // INFO
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL
     F77_CHAR_ARG_LEN_DECL);
  };

  // template specializations
  typedef real_ggsvd3_ptr<F77_DBLE>::type dggsvd3_type;
  typedef real_ggsvd_ptr<F77_DBLE>::type dggsvd_type;
  typedef real_ggsvd3_ptr<F77_REAL>::type sggsvd3_type;
  typedef real_ggsvd_ptr<F77_REAL>::type sggsvd_type;
  typedef comp_ggsvd3_ptr<F77_DBLE_CMPLX, F77_DBLE>::type zggsvd3_type;
  typedef comp_ggsvd_ptr<F77_DBLE_CMPLX, F77_DBLE>::type zggsvd_type;
  typedef comp_ggsvd3_ptr<F77_CMPLX, F77_REAL>::type cggsvd3_type;
  typedef comp_ggsvd_ptr<F77_CMPLX, F77_REAL>::type cggsvd_type;

  namespace math
  {
    template <>
    void
    gsvd<Matrix>::ggsvd (char& jobu, char& jobv, char& jobq, F77_INT m,
                         F77_INT n, F77_INT p, F77_INT& k, F77_INT& l,
                         double *tmp_dataA, F77_INT m1, double *tmp_dataB,
                         F77_INT p1, Matrix& alpha, Matrix& beta, double *u,
                         F77_INT nrow_u, double *v, F77_INT nrow_v, double *q,
                         F77_INT nrow_q, Matrix& work, F77_INT lwork,
                         F77_INT *iwork, F77_INT& info)
    {
      if (! gsvd_initialized)
        initialize_gsvd ();

      if (have_DGGSVD3)
        {
          dggsvd3_type f_ptr = reinterpret_cast<dggsvd3_type> (gsvd_fcn["dg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l, tmp_dataA, m1, tmp_dataB, p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 u, nrow_u, v, nrow_v, q, nrow_q,
                 work.fortran_vec (), lwork, iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
      else
        {
          dggsvd_type f_ptr = reinterpret_cast<dggsvd_type> (gsvd_fcn["dg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l, tmp_dataA, m1, tmp_dataB, p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 u, nrow_u, v, nrow_v, q, nrow_q,
                 work.fortran_vec (), iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
    }

    template <>
    void
    gsvd<FloatMatrix>::ggsvd (char& jobu, char& jobv, char& jobq, F77_INT m,
                              F77_INT n, F77_INT p, F77_INT& k, F77_INT& l,
                              float *tmp_dataA, F77_INT m1, float *tmp_dataB,
                              F77_INT p1, FloatMatrix& alpha,
                              FloatMatrix& beta, float *u, F77_INT nrow_u,
                              float *v, F77_INT nrow_v, float *q,
                              F77_INT nrow_q, FloatMatrix& work,
                              F77_INT lwork, F77_INT *iwork, F77_INT& info)
    {
      if (! gsvd_initialized)
        initialize_gsvd ();

      if (have_DGGSVD3)
        {
          sggsvd3_type f_ptr = reinterpret_cast<sggsvd3_type> (gsvd_fcn["sg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l, tmp_dataA, m1, tmp_dataB, p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 u, nrow_u, v, nrow_v, q, nrow_q,
                 work.fortran_vec (), lwork, iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
      else
        {
          sggsvd_type f_ptr = reinterpret_cast<sggsvd_type> (gsvd_fcn["sg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l, tmp_dataA, m1, tmp_dataB, p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 u, nrow_u, v, nrow_v, q, nrow_q,
                 work.fortran_vec (), iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
    }

    template <>
    void
    gsvd<ComplexMatrix>::ggsvd (char& jobu, char& jobv, char& jobq,
                                F77_INT m, F77_INT n, F77_INT p, F77_INT& k,
                                F77_INT& l, Complex *tmp_dataA, F77_INT m1,
                                Complex *tmp_dataB, F77_INT p1, Matrix& alpha,
                                Matrix& beta, Complex *u, F77_INT nrow_u,
                                Complex *v, F77_INT nrow_v, Complex *q,
                                F77_INT nrow_q, ComplexMatrix& work,
                                F77_INT lwork, F77_INT *iwork, F77_INT& info)
    {
      if (! gsvd_initialized)
        initialize_gsvd ();

      Matrix rwork(2*n, 1);
      if (have_DGGSVD3)
        {
          zggsvd3_type f_ptr = reinterpret_cast<zggsvd3_type> (gsvd_fcn["zg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l,
                 F77_DBLE_CMPLX_ARG (tmp_dataA), m1,
                 F77_DBLE_CMPLX_ARG (tmp_dataB), p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 F77_DBLE_CMPLX_ARG (u), nrow_u,
                 F77_DBLE_CMPLX_ARG (v), nrow_v,
                 F77_DBLE_CMPLX_ARG (q), nrow_q,
                 F77_DBLE_CMPLX_ARG (work.fortran_vec ()),
                 lwork, rwork.fortran_vec (), iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
      else
        {
          zggsvd_type f_ptr = reinterpret_cast<zggsvd_type> (gsvd_fcn["zg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l,
                 F77_DBLE_CMPLX_ARG (tmp_dataA), m1,
                 F77_DBLE_CMPLX_ARG (tmp_dataB), p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 F77_DBLE_CMPLX_ARG (u), nrow_u,
                 F77_DBLE_CMPLX_ARG (v), nrow_v,
                 F77_DBLE_CMPLX_ARG (q), nrow_q,
                 F77_DBLE_CMPLX_ARG (work.fortran_vec ()),
                 rwork.fortran_vec (), iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
    }

    template <>
    void
    gsvd<FloatComplexMatrix>::ggsvd (char& jobu, char& jobv, char& jobq,
                                     F77_INT m, F77_INT n, F77_INT p,
                                     F77_INT& k, F77_INT& l,
                                     FloatComplex *tmp_dataA, F77_INT m1,
                                     FloatComplex *tmp_dataB, F77_INT p1,
                                     FloatMatrix& alpha, FloatMatrix& beta,
                                     FloatComplex *u, F77_INT nrow_u,
                                     FloatComplex *v, F77_INT nrow_v,
                                     FloatComplex *q, F77_INT nrow_q,
                                     FloatComplexMatrix& work, F77_INT lwork,
                                     F77_INT *iwork, F77_INT& info)
    {
      if (! gsvd_initialized)
        initialize_gsvd ();

      FloatMatrix rwork(2*n, 1);
      if (have_DGGSVD3)
        {
          cggsvd3_type f_ptr = reinterpret_cast<cggsvd3_type> (gsvd_fcn["cg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l,
                 F77_CMPLX_ARG (tmp_dataA), m1,
                 F77_CMPLX_ARG (tmp_dataB), p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 F77_CMPLX_ARG (u), nrow_u,
                 F77_CMPLX_ARG (v), nrow_v,
                 F77_CMPLX_ARG (q), nrow_q,
                 F77_CMPLX_ARG (work.fortran_vec ()), lwork,
                 rwork.fortran_vec (), iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
      else
        {
          cggsvd_type f_ptr = reinterpret_cast<cggsvd_type> (gsvd_fcn["cg"]);
          f_ptr (F77_CONST_CHAR_ARG2 (&jobu, 1),
                 F77_CONST_CHAR_ARG2 (&jobv, 1),
                 F77_CONST_CHAR_ARG2 (&jobq, 1),
                 m, n, p, k, l,
                 F77_CMPLX_ARG (tmp_dataA), m1,
                 F77_CMPLX_ARG (tmp_dataB), p1,
                 alpha.fortran_vec (), beta.fortran_vec (),
                 F77_CMPLX_ARG (u), nrow_u,
                 F77_CMPLX_ARG (v), nrow_v,
                 F77_CMPLX_ARG (q), nrow_q,
                 F77_CMPLX_ARG (work.fortran_vec ()),
                 rwork.fortran_vec (), iwork, info
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1)
                 F77_CHAR_ARG_LEN (1));
        }
    }

    template <typename T>
    T
    gsvd<T>::left_singular_matrix_A (void) const
    {
      if (type == gsvd::Type::sigma_only)
        {
          (*current_liboctave_error_handler)
            ("gsvd: U not computed because type == gsvd::sigma_only");
          return T ();
        }
      else
        return left_smA;
    }

    template <typename T>
    T
    gsvd<T>::left_singular_matrix_B (void) const
    {
      if (type == gsvd::Type::sigma_only)
        {
          (*current_liboctave_error_handler)
            ("gsvd: V not computed because type == gsvd::sigma_only");
          return T ();
        }
      else
        return left_smB;
    }

    template <typename T>
    T
    gsvd<T>::right_singular_matrix (void) const
    {
      if (type == gsvd::Type::sigma_only)
        {
          (*current_liboctave_error_handler)
            ("gsvd: X not computed because type == gsvd::sigma_only");
          return T ();
        }
      else
        return right_sm;
    }

    template <typename T>
    T
    gsvd<T>::R_matrix (void) const
    {
      if (type != gsvd::Type::std)
        {
          (*current_liboctave_error_handler)
            ("gsvd: R not computed because type != gsvd::std");
          return T ();
        }
      else
        return R;
    }

    template <typename T>
    gsvd<T>::gsvd (const T& a, const T& b, gsvd::Type gsvd_type)
    {
      F77_INT info;

      F77_INT m = to_f77_int (a.rows ());
      F77_INT n = to_f77_int (a.cols ());
      F77_INT p = to_f77_int (b.rows ());

      T atmp = a;
      P *tmp_dataA = atmp.fortran_vec ();

      T btmp = b;
      P *tmp_dataB = btmp.fortran_vec ();

      char jobu = 'U';
      char jobv = 'V';
      char jobq = 'Q';

      F77_INT nrow_u = m;
      F77_INT nrow_v = p;
      F77_INT nrow_q = n;

      F77_INT k, l;

      switch (gsvd_type)
        {
        case gsvd<T>::Type::sigma_only:

          // Note:  for this case, both jobu and jobv should be 'N', but
          // there seems to be a bug in dgesvd from Lapack V2.0.  To
          // demonstrate the bug, set both jobu and jobv to 'N' and find
          // the singular values of [eye(3), eye(3)].  The result is
          // [-sqrt(2), -sqrt(2), -sqrt(2)].
          //
          // For Lapack 3.0, this problem seems to be fixed.

          jobu = 'N';
          jobv = 'N';
          jobq = 'N';
          nrow_u = nrow_v = nrow_q = 1;
          break;

        default:
          break;
        }

      type = gsvd_type;

      if (! (jobu == 'N' || jobu == 'O'))
        left_smA.resize (nrow_u, m);

      P *u = left_smA.fortran_vec ();

      if (! (jobv == 'N' || jobv == 'O'))
        left_smB.resize (nrow_v, p);

      P *v = left_smB.fortran_vec ();

      if (! (jobq == 'N' || jobq == 'O'))
        right_sm.resize (nrow_q, n);

      P *q = right_sm.fortran_vec ();

      real_matrix alpha (n, 1);
      real_matrix beta (n, 1);

      std::vector<F77_INT> iwork (n);

      if (! gsvd_initialized)
        initialize_gsvd ();

      F77_INT lwork;
      if (have_DGGSVD3)
        {
          lwork = -1;
          T work_tmp (1, 1);

          gsvd<T>::ggsvd (jobu, jobv, jobq, m, n, p, k, l,
                          tmp_dataA, m, tmp_dataB, p, alpha, beta, u,
                          nrow_u, v, nrow_v, q, nrow_q, work_tmp, lwork,
                          iwork.data (), info);

          lwork = static_cast<F77_INT> (std::abs (work_tmp(0, 0)));
        }
      else
        {
          lwork = 3*n;
          lwork = (lwork > m ? lwork : m);
          lwork = (lwork > p ? lwork : p) + n;
        }
      info = 0;

      T work (lwork, 1);

      gsvd<T>::ggsvd (jobu, jobv, jobq, m, n, p, k, l,
                      tmp_dataA, m, tmp_dataB, p, alpha, beta, u,
                      nrow_u, v, nrow_v, q, nrow_q, work, lwork, iwork.data (),
                      info);

      if (info < 0)
        (*current_liboctave_error_handler) ("*ggsvd.f: argument %d illegal",
                                            -info);
      else
        {
          if (info > 0)
            (*current_liboctave_error_handler)
              ("*ggsvd.f: Jacobi-type procedure failed to converge.");
          else
            {
              F77_INT i, j;

              if (gsvd<T>::Type::std == gsvd_type)
                {
                  R.resize(k+l, k+l);
                  int astart = n-k-l;
                  if (m - k - l >=  0)
                    {
                      astart = n-k-l;
                      // R is stored in A(1:K+L,N-K-L+1:N)
                      for (i = 0; i < k+l; i++)
                        for (j = 0; j < k+l; j++)
                          R.xelem (i, j) = atmp.xelem (i, astart + j);
                    }
                  else
                    {
                      // (R11 R12 R13 ) is stored in A(1:M, N-K-L+1:N),
                      // ( 0  R22 R23 )

                      for (i = 0; i < m; i++)
                        for (j = 0; j < k+l; j++)
                          R.xelem (i, j) = atmp.xelem (i, astart + j);
                      // and R33 is stored in B(M-K+1:L,N+M-K-L+1:N)
                      for (i = k+l-1; i >=m; i--)
                        {
                          for (j = 0; j < m; j++)
                            R.xelem(i, j) = 0.0;
                          for (j = m; j < k+l; j++)
                            R.xelem (i, j) = btmp.xelem (i - k, astart + j);
                        }
                    }
                }

              if (m-k-l >= 0)
                {
                  // Fills in C and S
                  sigmaA.resize (l, l);
                  sigmaB.resize (l, l);
                  for (i = 0; i < l; i++)
                    {
                      sigmaA.dgxelem(i) = alpha.elem(k+i);
                      sigmaB.dgxelem(i) = beta.elem(k+i);
                    }
                }
              else
                {
                  // Fills in C and S
                  sigmaA.resize (m-k, m-k);
                  sigmaB.resize (m-k, m-k);
                  for (i = 0; i < m-k; i++)
                    {
                      sigmaA.dgxelem(i) = alpha.elem(k+i);
                      sigmaB.dgxelem(i) = beta.elem(k+i);
                    }
                }
            }
        }
    }

    // Instantiations we need.
    template class gsvd<Matrix>;
    template class gsvd<FloatMatrix>;
    template class gsvd<ComplexMatrix>;
    template class gsvd<FloatComplexMatrix>;
  }
}