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/* ../../../dependencies/lapack/src/sorgl2.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"
/* Subroutine */ int sorgl2_(integer *m, integer *n, integer *k, real *a,
integer *lda, real *tau, real *work, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2;
real r__1;
/* Local variables */
static integer i__, j, l;
extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *),
slarf_(char *, integer *, integer *, real *, integer *, real *,
real *, integer *, real *, ftnlen), xerbla_(char *, integer *,
ftnlen);
/* -- 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 */
/* ======= */
/* SORGL2 generates an m by n real matrix Q with orthonormal rows, */
/* which is defined as the first m rows of a product of k elementary */
/* reflectors of order n */
/* Q = H(k) . . . H(2) H(1) */
/* as returned by SGELQF. */
/* 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. N >= M. */
/* K (input) INTEGER */
/* The number of elementary reflectors whose product defines the */
/* matrix Q. M >= K >= 0. */
/* A (input/output) REAL array, dimension (LDA,N) */
/* On entry, the i-th row must contain the vector which defines */
/* the elementary reflector H(i), for i = 1,2,...,k, as returned */
/* by SGELQF in the first k rows 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) REAL array, dimension (K) */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i), as returned by SGELQF. */
/* WORK (workspace) REAL array, dimension (M) */
/* 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 < *m) {
*info = -2;
} else if (*k < 0 || *k > *m) {
*info = -3;
} else if (*lda < max(1,*m)) {
*info = -5;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SORGL2", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*m <= 0) {
return 0;
}
if (*k < *m) {
/* Initialise rows k+1:m to rows of the unit matrix */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *m;
for (l = *k + 1; l <= i__2; ++l) {
a[l + j * a_dim1] = 0.f;
/* L10: */
}
if (j > *k && j <= *m) {
a[j + j * a_dim1] = 1.f;
}
/* L20: */
}
}
for (i__ = *k; i__ >= 1; --i__) {
/* Apply H(i) to A(i:m,i:n) from the right */
if (i__ < *n) {
if (i__ < *m) {
a[i__ + i__ * a_dim1] = 1.f;
i__1 = *m - i__;
i__2 = *n - i__ + 1;
slarf_("Right", &i__1, &i__2, &a[i__ + i__ * a_dim1], lda, &
tau[i__], &a[i__ + 1 + i__ * a_dim1], lda, &work[1], (
ftnlen)5);
}
i__1 = *n - i__;
r__1 = -tau[i__];
sscal_(&i__1, &r__1, &a[i__ + (i__ + 1) * a_dim1], lda);
}
a[i__ + i__ * a_dim1] = 1.f - tau[i__];
/* Set A(i,1:i-1) to zero */
i__1 = i__ - 1;
for (l = 1; l <= i__1; ++l) {
a[i__ + l * a_dim1] = 0.f;
/* L30: */
}
/* L40: */
}
return 0;
/* End of SORGL2 */
} /* sorgl2_ */
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