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/* ../../../dependencies/lapack/src/dorgtr.f -- translated by f2c (version 20061008).
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;
/* Subroutine */ int dorgtr_(char *uplo, integer *n, doublereal *a, integer *
lda, doublereal *tau, doublereal *work, integer *lwork, integer *info,
ftnlen uplo_len)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
/* Local variables */
static integer i__, j, nb;
extern logical lsame_(char *, char *, ftnlen, ftnlen);
static integer iinfo;
static logical upper;
extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen);
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;
/* -- 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 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* 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 */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input arguments */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--tau;
--work;
/* Function Body */
*info = 0;
lquery = *lwork == -1;
upper = lsame_(uplo, "U", (ftnlen)1, (ftnlen)1);
if (! upper && ! lsame_(uplo, "L", (ftnlen)1, (ftnlen)1)) {
*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, (ftnlen)6);
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[i__ + j * a_dim1] = a[i__ + (j + 1) * a_dim1];
/* L10: */
}
a[*n + j * a_dim1] = 0.;
/* L20: */
}
i__1 = *n - 1;
for (i__ = 1; i__ <= i__1; ++i__) {
a[i__ + *n * a_dim1] = 0.;
/* L30: */
}
a[*n + *n * a_dim1] = 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[j * a_dim1 + 1] = 0.;
i__1 = *n;
for (i__ = j + 1; i__ <= i__1; ++i__) {
a[i__ + j * a_dim1] = a[i__ + (j - 1) * a_dim1];
/* L40: */
}
/* L50: */
}
a[a_dim1 + 1] = 1.;
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
a[i__ + a_dim1] = 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[(a_dim1 << 1) + 2], lda, &tau[1],
&work[1], lwork, &iinfo);
}
}
work[1] = (doublereal) lwkopt;
return 0;
/* End of DORGTR */
} /* dorgtr_ */
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