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qr.cc
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1997-07-10
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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.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "CmplxQR.h"
#include "CmplxQRP.h"
#include "dbleQR.h"
#include "dbleQRP.h"
#include "defun-dld.h"
#include "error.h"
#include "gripes.h"
#include "help.h"
#include "oct-obj.h"
#include "utils.h"
DEFUN_DLD (qr, args, nargout,
"[Q, R] = qr (X): form Q unitary and R upper triangular such\n\
that Q * R = X\n\
\n\
[Q, R] = qr (X, 0): form the economy decomposition such that if X is\n\
m by n then only the first n columns of Q are\n\
computed.\n\
\n\
[Q, R, P] = qr (X): form QRP factorization of X where\n\
P is a permutation matrix such that\n\
A * P = Q * R\n\
\n\
[Q, R, P] = qr (X, 0): form the economy decomposition with \n\
permutation vector P such that Q * R = X (:, P)\n\
\n\
qr (X) alone returns the output of the LAPACK routine dgeqrf, such\n\
that R = triu (qr (X))")
{
octave_value_list retval;
int nargin = args.length ();
if (nargin != 1 && nargin != 2 || nargout > 3)
{
print_usage ("qr");
return retval;
}
octave_value arg = args(0);
int arg_is_empty = empty_arg ("qr", arg.rows (), arg.columns ());
if (arg_is_empty < 0)
return retval;
else if (arg_is_empty > 0)
return octave_value_list (3, Matrix ());
QR::type type = (nargout == 0 || nargout == 1) ? QR::raw
: (nargin == 2 ? QR::economy : QR::std);
if (arg.is_real_type ())
{
Matrix m = arg.matrix_value ();
if (! error_state)
{
switch (nargout)
{
case 0:
case 1:
{
QR fact (m, type);
retval(0) = fact.R ();
}
break;
case 2:
{
QR fact (m, type);
retval(1) = fact.R ();
retval(0) = fact.Q ();
}
break;
default:
{
QRP fact (m, type);
retval(2) = fact.P ();
retval(1) = fact.R ();
retval(0) = fact.Q ();
}
break;
}
}
}
else if (arg.is_complex_type ())
{
ComplexMatrix m = arg.complex_matrix_value ();
if (! error_state)
{
switch (nargout)
{
case 0:
case 1:
{
ComplexQR fact (m, type);
retval(0) = fact.R ();
}
break;
case 2:
{
ComplexQR fact (m, type);
retval(1) = fact.R ();
retval(0) = fact.Q ();
}
break;
default:
{
ComplexQRP fact (m, type);
retval(2) = fact.P ();
retval(1) = fact.R ();
retval(0) = fact.Q ();
}
break;
}
}
}
else
{
gripe_wrong_type_arg ("qr", arg);
}
return retval;
}
/*
;;; Local Variables: ***
;;; mode: C++ ***
;;; End: ***
*/