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/* cungr2.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"
/* Subroutine */ int cungr2_(integer *m, integer *n, integer *k, complex *a,
integer *lda, complex *tau, complex *work, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
complex q__1, q__2;
/* Builtin functions */
void r_cnjg(complex *, complex *);
/* Local variables */
integer i__, j, l, ii;
extern /* Subroutine */ int cscal_(integer *, complex *, complex *,
integer *), clarf_(char *, integer *, integer *, complex *,
integer *, complex *, complex *, integer *, complex *),
clacgv_(integer *, complex *, integer *), 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 */
/* ======= */
/* CUNGR2 generates an m by n complex matrix Q with orthonormal rows, */
/* which is defined as the last m rows of a product of k elementary */
/* reflectors of order n */
/* Q = H(1)' H(2)' . . . H(k)' */
/* as returned by CGERQF. */
/* 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) COMPLEX array, dimension (LDA,N) */
/* On entry, the (m-k+i)-th row must contain the vector which */
/* defines the elementary reflector H(i), for i = 1,2,...,k, as */
/* returned by CGERQF in the last 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) COMPLEX array, dimension (K) */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i), as returned by CGERQF. */
/* WORK (workspace) COMPLEX 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_("CUNGR2", &i__1);
return 0;
}
/* Quick return if possible */
if (*m <= 0) {
return 0;
}
if (*k < *m) {
/* Initialise rows 1:m-k to rows of the unit matrix */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *m - *k;
for (l = 1; l <= i__2; ++l) {
i__3 = l + j * a_dim1;
a[i__3].r = 0.f, a[i__3].i = 0.f;
/* L10: */
}
if (j > *n - *m && j <= *n - *k) {
i__2 = *m - *n + j + j * a_dim1;
a[i__2].r = 1.f, a[i__2].i = 0.f;
}
/* L20: */
}
}
i__1 = *k;
for (i__ = 1; i__ <= i__1; ++i__) {
ii = *m - *k + i__;
/* Apply H(i)' to A(1:m-k+i,1:n-k+i) from the right */
i__2 = *n - *m + ii - 1;
clacgv_(&i__2, &a[ii + a_dim1], lda);
i__2 = ii + (*n - *m + ii) * a_dim1;
a[i__2].r = 1.f, a[i__2].i = 0.f;
i__2 = ii - 1;
i__3 = *n - *m + ii;
r_cnjg(&q__1, &tau[i__]);
clarf_("Right", &i__2, &i__3, &a[ii + a_dim1], lda, &q__1, &a[
a_offset], lda, &work[1]);
i__2 = *n - *m + ii - 1;
i__3 = i__;
q__1.r = -tau[i__3].r, q__1.i = -tau[i__3].i;
cscal_(&i__2, &q__1, &a[ii + a_dim1], lda);
i__2 = *n - *m + ii - 1;
clacgv_(&i__2, &a[ii + a_dim1], lda);
i__2 = ii + (*n - *m + ii) * a_dim1;
r_cnjg(&q__2, &tau[i__]);
q__1.r = 1.f - q__2.r, q__1.i = 0.f - q__2.i;
a[i__2].r = q__1.r, a[i__2].i = q__1.i;
/* Set A(m-k+i,n-k+i+1:n) to zero */
i__2 = *n;
for (l = *n - *m + ii + 1; l <= i__2; ++l) {
i__3 = ii + l * a_dim1;
a[i__3].r = 0.f, a[i__3].i = 0.f;
/* L30: */
}
/* L40: */
}
return 0;
/* End of CUNGR2 */
} /* cungr2_ */
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