/* -- translated by f2c (version 20100827).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
/* Table of constant values */
static integer c__1 = 1;
static integer c_n1 = -1;
/* > \brief \b DORGHR
=========== DOCUMENTATION ===========
Online html documentation available at
http://www.netlib.org/lapack/explore-html/
> \htmlonly
> Download DORGHR + dependencies
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dorghr.
f">
> [TGZ]</a>
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dorghr.
f">
> [ZIP]</a>
> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dorghr.
f">
> [TXT]</a>
> \endhtmlonly
Definition:
===========
SUBROUTINE DORGHR( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO )
INTEGER IHI, ILO, INFO, LDA, LWORK, N
DOUBLE PRECISION A( LDA, * ), TAU( * ), WORK( * )
> \par Purpose:
=============
>
> \verbatim
>
> DORGHR generates a real orthogonal matrix Q which is defined as the
> product of IHI-ILO elementary reflectors of order N, as returned by
> DGEHRD:
>
> Q = H(ilo) H(ilo+1) . . . H(ihi-1).
> \endverbatim
Arguments:
==========
> \param[in] N
> \verbatim
> N is INTEGER
> The order of the matrix Q. N >= 0.
> \endverbatim
>
> \param[in] ILO
> \verbatim
> ILO is INTEGER
> \endverbatim
>
> \param[in] IHI
> \verbatim
> IHI is INTEGER
>
> ILO and IHI must have the same values as in the previous call
> of DGEHRD. Q is equal to the unit matrix except in the
> submatrix Q(ilo+1:ihi,ilo+1:ihi).
> 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
> \endverbatim
>
> \param[in,out] A
> \verbatim
> A is DOUBLE PRECISION array, dimension (LDA,N)
> On entry, the vectors which define the elementary reflectors,
> as returned by DGEHRD.
> On exit, the N-by-N orthogonal matrix Q.
> \endverbatim
>
> \param[in] LDA
> \verbatim
> LDA is INTEGER
> The leading dimension of the array A. LDA >= max(1,N).
> \endverbatim
>
> \param[in] TAU
> \verbatim
> TAU is DOUBLE PRECISION array, dimension (N-1)
> TAU(i) must contain the scalar factor of the elementary
> reflector H(i), as returned by DGEHRD.
> \endverbatim
>
> \param[out] WORK
> \verbatim
> WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
> On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
> \endverbatim
>
> \param[in] LWORK
> \verbatim
> LWORK is INTEGER
> The dimension of the array WORK. LWORK >= IHI-ILO.
> For optimum performance LWORK >= (IHI-ILO)*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.
> \endverbatim
>
> \param[out] INFO
> \verbatim
> INFO is INTEGER
> = 0: successful exit
> < 0: if INFO = -i, the i-th argument had an illegal value
> \endverbatim
Authors:
========
> \author Univ. of Tennessee
> \author Univ. of California Berkeley
> \author Univ. of Colorado Denver
> \author NAG Ltd.
> \date November 2011
> \ingroup doubleOTHERcomputational
=====================================================================
Subroutine */ int igraphdorghr_(integer *n, integer *ilo, integer *ihi,
doublereal *a, integer *lda, doublereal *tau, doublereal *work,
integer *lwork, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2;
/* Local variables */
integer i__, j, nb, nh, iinfo;
extern /* Subroutine */ int igraphxerbla_(char *, integer *, ftnlen);
extern integer igraphilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *, ftnlen, ftnlen);
extern /* Subroutine */ int igraphdorgqr_(integer *, integer *, integer *,
doublereal *, integer *, doublereal *, doublereal *, integer *,
integer *);
integer lwkopt;
logical lquery;
/* -- LAPACK computational routine (version 3.4.0) --
-- LAPACK is a software package provided by Univ. of Tennessee, --
-- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
November 2011
=====================================================================
Test the input arguments
Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--tau;
--work;
/* Function Body */
*info = 0;
nh = *ihi - *ilo;
lquery = *lwork == -1;
if (*n < 0) {
*info = -1;
} else if (*ilo < 1 || *ilo > max(1,*n)) {
*info = -2;
} else if (*ihi < min(*ilo,*n) || *ihi > *n) {
*info = -3;
} else if (*lda < max(1,*n)) {
*info = -5;
} else if (*lwork < max(1,nh) && ! lquery) {
*info = -8;
}
if (*info == 0) {
nb = igraphilaenv_(&c__1, "DORGQR", " ", &nh, &nh, &nh, &c_n1, (ftnlen)6, (
ftnlen)1);
lwkopt = max(1,nh) * nb;
work[1] = (doublereal) lwkopt;
}
if (*info != 0) {
i__1 = -(*info);
igraphxerbla_("DORGHR", &i__1, (ftnlen)6);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible */
if (*n == 0) {
work[1] = 1.;
return 0;
}
/* Shift the vectors which define the elementary reflectors one
column to the right, and set the first ilo and the last n-ihi
rows and columns to those of the unit matrix */
i__1 = *ilo + 1;
for (j = *ihi; j >= i__1; --j) {
i__2 = j - 1;
for (i__ = 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] = 0.;
/* L10: */
}
i__2 = *ihi;
for (i__ = j + 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] = a[i__ + (j - 1) * a_dim1];
/* L20: */
}
i__2 = *n;
for (i__ = *ihi + 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] = 0.;
/* L30: */
}
/* L40: */
}
i__1 = *ilo;
for (j = 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] = 0.;
/* L50: */
}
a[j + j * a_dim1] = 1.;
/* L60: */
}
i__1 = *n;
for (j = *ihi + 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] = 0.;
/* L70: */
}
a[j + j * a_dim1] = 1.;
/* L80: */
}
if (nh > 0) {
/* Generate Q(ilo+1:ihi,ilo+1:ihi) */
igraphdorgqr_(&nh, &nh, &nh, &a[*ilo + 1 + (*ilo + 1) * a_dim1], lda, &tau[*
ilo], &work[1], lwork, &iinfo);
}
work[1] = (doublereal) lwkopt;
return 0;
/* End of DORGHR */
} /* igraphdorghr_ */