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dbleGEPBAL.cc
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1996-03-03
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/*
Copyright (C) 1996 John W. Eaton
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 2, 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, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#if defined (__GNUG__)
#pragma implementation
#endif
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <cmath>
#include <string>
#include "dbleGEPBAL.h"
#include "f77-fcn.h"
extern "C"
{
int F77_FCN (dgebak, DGEBAK) (const char*, const char*, const int&,
const int&, const int&, double*,
const int&, double*, const int&, int&,
long, long);
int F77_FCN (reduce, REDUCE) (const int&, const int&, double*,
const int&, double*, int&, int&,
double*, double*);
int F77_FCN (scaleg, SCALEG) (const int&, const int&, double*,
const int&, double*, const int&,
const int&, double*, double*,
double*);
int F77_FCN (gradeq, GRADEQ) (const int&, const int&, double*,
const int&, double*, int&, int&,
double*, double*);
}
int
GEPBALANCE::init (const Matrix& a, const Matrix& b, const string& balance_job)
{
int a_nr = a.rows ();
int a_nc = a.cols ();
int b_nr = b.rows ();
if (a_nr != a_nc || a_nr != b_nr || b_nr != b.cols ())
{
(*current_liboctave_error_handler)
("GEPBALANCE requires square matrices of the same size");
return -1;
}
int n = a_nc;
int info;
int ilo;
int ihi;
Array<double> cscale (n);
double *pcscale = cscale.fortran_vec ();
Matrix wk (n, 6, 0.0);
double *pwk = wk.fortran_vec ();
// Back out the permutations:
//
// cscale contains the exponents of the column scaling factors in its
// ilo through ihi locations and the reducing column permutations in
// its first ilo-1 and its ihi+1 through n locations.
//
// cperm contains the column permutations applied in grading the a and b
// submatrices in its ilo through ihi locations.
//
// wk contains the exponents of the row scaling factors in its ilo
// through ihi locations, the reducing row permutations in its first
// ilo-1 and its ihi+1 through n locations, and the row permutations
// applied in grading the a and b submatrices in its n+ilo through
// n+ihi locations.
// Copy matrices into local structure.
balanced_a_mat = a;
balanced_b_mat = b;
double *p_balanced_a_mat = balanced_a_mat.fortran_vec ();
double *p_balanced_b_mat = balanced_b_mat.fortran_vec ();
// Check for permutation option.
char job = balance_job[0];
if (job == 'P' || job == 'B')
{
F77_XFCN (reduce, REDUCE, (n, n, p_balanced_a_mat, n,
p_balanced_b_mat, ilo, ihi,
pcscale, pwk));
}
else
{
// Set up for scaling later.
ilo = 1;
ihi = n;
}
if (f77_exception_encountered)
(*current_liboctave_error_handler) ("unrecoverable error in reduce");
else
{
Array<double> cperm (n);
double *pcperm = cperm.fortran_vec ();
// Check for scaling option.
if ((job == 'S' || job == 'B') && ilo != ihi)
{
F77_XFCN (scaleg, SCALEG, (n, n, p_balanced_a_mat, n,
p_balanced_b_mat, ilo, ihi,
pcscale, pcperm, pwk));
}
else
{
// Set scaling data to 0's.
for (int i = ilo-1; i < ihi; i++)
{
cscale.elem (i) = 0.0;
wk.elem (i, 0) = 0.0;
}
}
if (f77_exception_encountered)
(*current_liboctave_error_handler) ("unrecoverable error in scaleg");
else
{
// Scaleg returns exponents, not values, so...
for (int i = ilo-1; i < ihi; i++)
{
cscale.elem (i) = pow (2.0, cscale.elem (i));
wk.elem (i, 0) = pow (2.0, -wk.elem (i, 0));
}
// Initialize balancing matrices to identity.
left_balancing_mat = Matrix (n, n, 0.0);
for (int i = 0; i < n; i++)
left_balancing_mat (i, i) = 1.0;
right_balancing_mat = left_balancing_mat;
double *p_right_balancing_mat = right_balancing_mat.fortran_vec ();
double *p_left_balancing_mat = left_balancing_mat.fortran_vec ();
// Column permutations/scaling.
char side = 'R';
F77_XFCN (dgebak, DGEBAK, (&job, &side, n, ilo, ihi, pcscale,
n, p_right_balancing_mat, n, info,
1L, 1L));
if (f77_exception_encountered)
(*current_liboctave_error_handler)
("unrecoverable error in dgebak");
else
{
// Row permutations/scaling.
side = 'L';
F77_XFCN (dgebak, DGEBAK, (&job, &side, n, ilo, ihi, pwk,
n, p_left_balancing_mat, n,
info, 1L, 1L));
#if 0
// XXX FIXME XXX --- these four lines need to be added and
// debugged. GEPBALANCE::init will work without them, though, so
// here they are.
if ((job == 'P' || job == 'B') && ilo != ihi)
{
F77_XFCN (gradeq, GRADEQ, (n, n, p_balanced_a_mat, n,
p_balanced_b_mat, ilo, ihi,
pcperm, pwk));
}
#endif
if (f77_exception_encountered)
(*current_liboctave_error_handler)
("unrecoverable error in dgebak");
else
{
// Transpose for aa = cc*a*dd convention...
left_balancing_mat = left_balancing_mat.transpose ();
}
}
}
}
return info;
}
/*
;;; Local Variables: ***
;;; mode: C++ ***
;;; End: ***
*/