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CmplxHESS.cc
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1 /*
2 
3 Copyright (C) 1994-2013 John W. Eaton
4 
5 This file is part of Octave.
6 
7 Octave is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 3 of the License, or (at your
10 option) any later version.
11 
12 Octave is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16 
17 You should have received a copy of the GNU General Public License
18 along with Octave; see the file COPYING. If not, see
19 <http://www.gnu.org/licenses/>.
20 
21 */
22 
23 #ifdef HAVE_CONFIG_H
24 #include <config.h>
25 #endif
26 
27 #include "CmplxHESS.h"
28 #include "f77-fcn.h"
29 #include "lo-error.h"
30 
31 extern "C"
32 {
33  F77_RET_T
34  F77_FUNC (zgebal, ZGEBAL) (F77_CONST_CHAR_ARG_DECL,
36  const octave_idx_type&, octave_idx_type&,
37  octave_idx_type&, double*, octave_idx_type&
39 
40  F77_RET_T
41  F77_FUNC (zgehrd, ZGEHRD) (const octave_idx_type&, const octave_idx_type&,
42  const octave_idx_type&, Complex*,
43  const octave_idx_type&, Complex*, Complex*,
44  const octave_idx_type&, octave_idx_type&);
45 
46  F77_RET_T
47  F77_FUNC (zunghr, ZUNGHR) (const octave_idx_type&, const octave_idx_type&,
48  const octave_idx_type&, Complex*,
49  const octave_idx_type&, Complex*, Complex*,
50  const octave_idx_type&, octave_idx_type&);
51 
52  F77_RET_T
53  F77_FUNC (zgebak, ZGEBAK) (F77_CONST_CHAR_ARG_DECL,
55  const octave_idx_type&, const octave_idx_type&,
56  const octave_idx_type&, double*,
57  const octave_idx_type&, Complex*,
58  const octave_idx_type&, octave_idx_type&
61 }
62 
65 {
66  octave_idx_type a_nr = a.rows ();
67  octave_idx_type a_nc = a.cols ();
68 
69  if (a_nr != a_nc)
70  {
71  (*current_liboctave_error_handler)
72  ("ComplexHESS requires square matrix");
73  return -1;
74  }
75 
76  char job = 'N';
77  char side = 'R';
78 
79  octave_idx_type n = a_nc;
80  octave_idx_type lwork = 32 * n;
81  octave_idx_type info;
82  octave_idx_type ilo;
83  octave_idx_type ihi;
84 
85  hess_mat = a;
87 
89  double *pscale = scale.fortran_vec ();
90 
91  F77_XFCN (zgebal, ZGEBAL, (F77_CONST_CHAR_ARG2 (&job, 1),
92  n, h, n, ilo, ihi, pscale, info
93  F77_CHAR_ARG_LEN (1)));
94 
95  Array<Complex> tau (dim_vector (n-1, 1));
96  Complex *ptau = tau.fortran_vec ();
97 
98  Array<Complex> work (dim_vector (lwork, 1));
99  Complex *pwork = work.fortran_vec ();
100 
101  F77_XFCN (zgehrd, ZGEHRD, (n, ilo, ihi, h, n, ptau, pwork, lwork, info));
102 
105 
106  F77_XFCN (zunghr, ZUNGHR, (n, ilo, ihi, z, n, ptau, pwork,
107  lwork, info));
108 
109  F77_XFCN (zgebak, ZGEBAK, (F77_CONST_CHAR_ARG2 (&job, 1),
110  F77_CONST_CHAR_ARG2 (&side, 1),
111  n, ilo, ihi, pscale, n, z, n, info
112  F77_CHAR_ARG_LEN (1)
113  F77_CHAR_ARG_LEN (1)));
114 
115  // If someone thinks of a more graceful way of
116  // doing this (or faster for that matter :-)),
117  // please let me know!
118 
119  if (n > 2)
120  for (octave_idx_type j = 0; j < a_nc; j++)
121  for (octave_idx_type i = j+2; i < a_nr; i++)
122  hess_mat.elem (i, j) = 0;
123 
124  return info;
125 }