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hypre/lapack/dorgtr.c
hill66 402d34179c Updated license info.
2006-09-22 22:06:21 +00:00

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/*BHEADER**********************************************************************
* Copyright (c) 2006 The Regents of the University of California.
* Produced at the Lawrence Livermore National Laboratory.
* Written by the HYPRE team. UCRL-CODE-222953.
* All rights reserved.
*
* This file is part of HYPRE (see http://www.llnl.gov/CASC/hypre/).
* Please see the COPYRIGHT_and_LICENSE file for the copyright notice,
* disclaimer, contact information and the GNU Lesser General Public License.
*
* HYPRE 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) version 2.1 dated February 1999.
*
* HYPRE 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 terms and conditions of the GNU General
* Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Revision$
***********************************************************************EHEADER*/
#include "hypre_lapack.h"
#include "f2c.h"
/* Subroutine */ int dorgtr_(char *uplo, integer *n, doublereal *a, integer *
lda, doublereal *tau, doublereal *work, integer *lwork, integer *info)
{
/* -- LAPACK routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
June 30, 1999
Purpose
=======
DORGTR generates a real orthogonal matrix Q which is defined as the
product of n-1 elementary reflectors of order N, as returned by
DSYTRD:
if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),
if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).
Arguments
=========
UPLO (input) CHARACTER*1
= 'U': Upper triangle of A contains elementary reflectors
from DSYTRD;
= 'L': Lower triangle of A contains elementary reflectors
from DSYTRD.
N (input) INTEGER
The order of the matrix Q. N >= 0.
A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the vectors which define the elementary reflectors,
as returned by DSYTRD.
On exit, the N-by-N orthogonal matrix Q.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
TAU (input) DOUBLE PRECISION array, dimension (N-1)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by DSYTRD.
WORK (workspace/output) DOUBLE PRECISION array, dimension (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input) INTEGER
The dimension of the array WORK. LWORK >= max(1,N-1).
For optimum performance LWORK >= (N-1)*NB, where NB is
the optimal blocksize.
If LWORK = -1, then a workspace query is assumed; the routine
only calculates the optimal size of the WORK array, returns
this value as the first entry of the WORK array, and no error
message related to LWORK is issued by XERBLA.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
=====================================================================
Test the input arguments
Parameter adjustments */
/* Table of constant values */
static integer c__1 = 1;
static integer c_n1 = -1;
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
/* Local variables */
static integer i__, j;
extern logical lsame_(char *, char *);
static integer iinfo;
static logical upper;
static integer nb;
extern /* Subroutine */ int xerbla_(char *, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *, ftnlen, ftnlen);
extern /* Subroutine */ int dorgql_(integer *, integer *, integer *,
doublereal *, integer *, doublereal *, doublereal *, integer *,
integer *), dorgqr_(integer *, integer *, integer *, doublereal *,
integer *, doublereal *, doublereal *, integer *, integer *);
static integer lwkopt;
static logical lquery;
#define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1]
a_dim1 = *lda;
a_offset = 1 + a_dim1 * 1;
a -= a_offset;
--tau;
--work;
/* Function Body */
*info = 0;
lquery = *lwork == -1;
upper = lsame_(uplo, "U");
if (! upper && ! lsame_(uplo, "L")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*lda < max(1,*n)) {
*info = -4;
} else /* if(complicated condition) */ {
/* Computing MAX */
i__1 = 1, i__2 = *n - 1;
if (*lwork < max(i__1,i__2) && ! lquery) {
*info = -7;
}
}
if (*info == 0) {
if (upper) {
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
nb = ilaenv_(&c__1, "DORGQL", " ", &i__1, &i__2, &i__3, &c_n1, (
ftnlen)6, (ftnlen)1);
} else {
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
nb = ilaenv_(&c__1, "DORGQR", " ", &i__1, &i__2, &i__3, &c_n1, (
ftnlen)6, (ftnlen)1);
}
/* Computing MAX */
i__1 = 1, i__2 = *n - 1;
lwkopt = max(i__1,i__2) * nb;
work[1] = (doublereal) lwkopt;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DORGTR", &i__1);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible */
if (*n == 0) {
work[1] = 1.;
return 0;
}
if (upper) {
/* Q was determined by a call to DSYTRD with UPLO = 'U'
Shift the vectors which define the elementary reflectors one
column to the left, and set the last row and column of Q to
those of the unit matrix */
i__1 = *n - 1;
for (j = 1; j <= i__1; ++j) {
i__2 = j - 1;
for (i__ = 1; i__ <= i__2; ++i__) {
a_ref(i__, j) = a_ref(i__, j + 1);
/* L10: */
}
a_ref(*n, j) = 0.;
/* L20: */
}
i__1 = *n - 1;
for (i__ = 1; i__ <= i__1; ++i__) {
a_ref(i__, *n) = 0.;
/* L30: */
}
a_ref(*n, *n) = 1.;
/* Generate Q(1:n-1,1:n-1) */
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
dorgql_(&i__1, &i__2, &i__3, &a[a_offset], lda, &tau[1], &work[1],
lwork, &iinfo);
} else {
/* Q was determined by a call to DSYTRD with UPLO = 'L'.
Shift the vectors which define the elementary reflectors one
column to the right, and set the first row and column of Q to
those of the unit matrix */
for (j = *n; j >= 2; --j) {
a_ref(1, j) = 0.;
i__1 = *n;
for (i__ = j + 1; i__ <= i__1; ++i__) {
a_ref(i__, j) = a_ref(i__, j - 1);
/* L40: */
}
/* L50: */
}
a_ref(1, 1) = 1.;
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
a_ref(i__, 1) = 0.;
/* L60: */
}
if (*n > 1) {
/* Generate Q(2:n,2:n) */
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
dorgqr_(&i__1, &i__2, &i__3, &a_ref(2, 2), lda, &tau[1], &work[1],
lwork, &iinfo);
}
}
work[1] = (doublereal) lwkopt;
return 0;
/* End of DORGTR */
} /* dorgtr_ */
#undef a_ref
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