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/* dorg2r.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"
#include "blaswrap.h"
/* Table of constant values */
static integer c__1 = 1;
/* Subroutine */ int dorg2r_(integer *m, integer *n, integer *k, doublereal *
a, integer *lda, doublereal *tau, doublereal *work, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2;
doublereal d__1;
/* Local variables */
integer i__, j, l;
extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
integer *), dlarf_(char *, integer *, integer *, doublereal *,
integer *, doublereal *, doublereal *, integer *, doublereal *), xerbla_(char *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DORG2R generates an m by n real matrix Q with orthonormal columns, */
/* which is defined as the first n columns of a product of k elementary */
/* reflectors of order m */
/* Q = H(1) H(2) . . . H(k) */
/* as returned by DGEQRF. */
/* Arguments */
/* ========= */
/* M (input) INTEGER */
/* The number of rows of the matrix Q. M >= 0. */
/* N (input) INTEGER */
/* The number of columns of the matrix Q. M >= N >= 0. */
/* K (input) INTEGER */
/* The number of elementary reflectors whose product defines the */
/* matrix Q. N >= K >= 0. */
/* A (input/output) DOUBLE PRECISION array, dimension (LDA,N) */
/* On entry, the i-th column must contain the vector which */
/* defines the elementary reflector H(i), for i = 1,2,...,k, as */
/* returned by DGEQRF in the first k columns of its array */
/* argument A. */
/* On exit, the m-by-n matrix Q. */
/* LDA (input) INTEGER */
/* The first dimension of the array A. LDA >= max(1,M). */
/* TAU (input) DOUBLE PRECISION array, dimension (K) */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i), as returned by DGEQRF. */
/* WORK (workspace) DOUBLE PRECISION array, dimension (N) */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument has an illegal value */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. 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;
if (*m < 0) {
*info = -1;
} else if (*n < 0 || *n > *m) {
*info = -2;
} else if (*k < 0 || *k > *n) {
*info = -3;
} else if (*lda < max(1,*m)) {
*info = -5;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DORG2R", &i__1);
return 0;
}
/* Quick return if possible */
if (*n <= 0) {
return 0;
}
/* Initialise columns k+1:n to columns of the unit matrix */
i__1 = *n;
for (j = *k + 1; j <= i__1; ++j) {
i__2 = *m;
for (l = 1; l <= i__2; ++l) {
a[l + j * a_dim1] = 0.;
/* L10: */
}
a[j + j * a_dim1] = 1.;
/* L20: */
}
for (i__ = *k; i__ >= 1; --i__) {
/* Apply H(i) to A(i:m,i:n) from the left */
if (i__ < *n) {
a[i__ + i__ * a_dim1] = 1.;
i__1 = *m - i__ + 1;
i__2 = *n - i__;
dlarf_("Left", &i__1, &i__2, &a[i__ + i__ * a_dim1], &c__1, &tau[
i__], &a[i__ + (i__ + 1) * a_dim1], lda, &work[1]);
}
if (i__ < *m) {
i__1 = *m - i__;
d__1 = -tau[i__];
dscal_(&i__1, &d__1, &a[i__ + 1 + i__ * a_dim1], &c__1);
}
a[i__ + i__ * a_dim1] = 1. - tau[i__];
/* Set A(1:i-1,i) to zero */
i__1 = i__ - 1;
for (l = 1; l <= i__1; ++l) {
a[l + i__ * a_dim1] = 0.;
/* L30: */
}
/* L40: */
}
return 0;
/* End of DORG2R */
} /* dorg2r_ */
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