/* cungbr.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;
static integer c_n1 = -1;
/* Subroutine */ int cungbr_(char *vect, integer *m, integer *n, integer *k,
complex *a, integer *lda, complex *tau, complex *work, integer *lwork,
integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
/* Local variables */
integer i__, j, nb, mn;
extern logical lsame_(char *, char *);
integer iinfo;
logical wantq;
extern /* Subroutine */ int xerbla_(char *, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
extern /* Subroutine */ int cunglq_(integer *, integer *, integer *,
complex *, integer *, complex *, complex *, integer *, integer *),
cungqr_(integer *, integer *, integer *, complex *, integer *,
complex *, complex *, integer *, integer *);
integer lwkopt;
logical lquery;
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CUNGBR generates one of the complex unitary matrices Q or P**H */
/* determined by CGEBRD when reducing a complex matrix A to bidiagonal */
/* form: A = Q * B * P**H. Q and P**H are defined as products of */
/* elementary reflectors H(i) or G(i) respectively. */
/* If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q */
/* is of order M: */
/* if m >= k, Q = H(1) H(2) . . . H(k) and CUNGBR returns the first n */
/* columns of Q, where m >= n >= k; */
/* if m < k, Q = H(1) H(2) . . . H(m-1) and CUNGBR returns Q as an */
/* M-by-M matrix. */
/* If VECT = 'P', A is assumed to have been a K-by-N matrix, and P**H */
/* is of order N: */
/* if k < n, P**H = G(k) . . . G(2) G(1) and CUNGBR returns the first m */
/* rows of P**H, where n >= m >= k; */
/* if k >= n, P**H = G(n-1) . . . G(2) G(1) and CUNGBR returns P**H as */
/* an N-by-N matrix. */
/* Arguments */
/* ========= */
/* VECT (input) CHARACTER*1 */
/* Specifies whether the matrix Q or the matrix P**H is */
/* required, as defined in the transformation applied by CGEBRD: */
/* = 'Q': generate Q; */
/* = 'P': generate P**H. */
/* M (input) INTEGER */
/* The number of rows of the matrix Q or P**H to be returned. */
/* M >= 0. */
/* N (input) INTEGER */
/* The number of columns of the matrix Q or P**H to be returned. */
/* N >= 0. */
/* If VECT = 'Q', M >= N >= min(M,K); */
/* if VECT = 'P', N >= M >= min(N,K). */
/* K (input) INTEGER */
/* If VECT = 'Q', the number of columns in the original M-by-K */
/* matrix reduced by CGEBRD. */
/* If VECT = 'P', the number of rows in the original K-by-N */
/* matrix reduced by CGEBRD. */
/* K >= 0. */
/* A (input/output) COMPLEX array, dimension (LDA,N) */
/* On entry, the vectors which define the elementary reflectors, */
/* as returned by CGEBRD. */
/* On exit, the M-by-N matrix Q or P**H. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= M. */
/* TAU (input) COMPLEX array, dimension */
/* (min(M,K)) if VECT = 'Q' */
/* (min(N,K)) if VECT = 'P' */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i) or G(i), which determines Q or P**H, as */
/* returned by CGEBRD in its array argument TAUQ or TAUP. */
/* WORK (workspace/output) COMPLEX array, dimension (MAX(1,LWORK)) */
/* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
/* LWORK (input) INTEGER */
/* The dimension of the array WORK. LWORK >= max(1,min(M,N)). */
/* For optimum performance LWORK >= min(M,N)*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;
wantq = lsame_(vect, "Q");
mn = min(*m,*n);
lquery = *lwork == -1;
if (! wantq && ! lsame_(vect, "P")) {
*info = -1;
} else if (*m < 0) {
*info = -2;
} else if (*n < 0 || wantq && (*n > *m || *n < min(*m,*k)) || ! wantq && (
*m > *n || *m < min(*n,*k))) {
*info = -3;
} else if (*k < 0) {
*info = -4;
} else if (*lda < max(1,*m)) {
*info = -6;
} else if (*lwork < max(1,mn) && ! lquery) {
*info = -9;
}
if (*info == 0) {
if (wantq) {
nb = ilaenv_(&c__1, "CUNGQR", " ", m, n, k, &c_n1);
} else {
nb = ilaenv_(&c__1, "CUNGLQ", " ", m, n, k, &c_n1);
}
lwkopt = max(1,mn) * nb;
work[1].r = (real) lwkopt, work[1].i = 0.f;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("CUNGBR", &i__1);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible */
if (*m == 0 || *n == 0) {
work[1].r = 1.f, work[1].i = 0.f;
return 0;
}
if (wantq) {
/* Form Q, determined by a call to CGEBRD to reduce an m-by-k */
/* matrix */
if (*m >= *k) {
/* If m >= k, assume m >= n >= k */
cungqr_(m, n, k, &a[a_offset], lda, &tau[1], &work[1], lwork, &
iinfo);
} else {
/* If m < k, assume m = n */
/* 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 = *m; j >= 2; --j) {
i__1 = j * a_dim1 + 1;
a[i__1].r = 0.f, a[i__1].i = 0.f;
i__1 = *m;
for (i__ = j + 1; i__ <= i__1; ++i__) {
i__2 = i__ + j * a_dim1;
i__3 = i__ + (j - 1) * a_dim1;
a[i__2].r = a[i__3].r, a[i__2].i = a[i__3].i;
/* L10: */
}
/* L20: */
}
i__1 = a_dim1 + 1;
a[i__1].r = 1.f, a[i__1].i = 0.f;
i__1 = *m;
for (i__ = 2; i__ <= i__1; ++i__) {
i__2 = i__ + a_dim1;
a[i__2].r = 0.f, a[i__2].i = 0.f;
/* L30: */
}
if (*m > 1) {
/* Form Q(2:m,2:m) */
i__1 = *m - 1;
i__2 = *m - 1;
i__3 = *m - 1;
cungqr_(&i__1, &i__2, &i__3, &a[(a_dim1 << 1) + 2], lda, &tau[
1], &work[1], lwork, &iinfo);
}
}
} else {
/* Form P', determined by a call to CGEBRD to reduce a k-by-n */
/* matrix */
if (*k < *n) {
/* If k < n, assume k <= m <= n */
cunglq_(m, n, k, &a[a_offset], lda, &tau[1], &work[1], lwork, &
iinfo);
} else {
/* If k >= n, assume m = n */
/* Shift the vectors which define the elementary reflectors one */
/* row downward, and set the first row and column of P' to */
/* those of the unit matrix */
i__1 = a_dim1 + 1;
a[i__1].r = 1.f, a[i__1].i = 0.f;
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
i__2 = i__ + a_dim1;
a[i__2].r = 0.f, a[i__2].i = 0.f;
/* L40: */
}
i__1 = *n;
for (j = 2; j <= i__1; ++j) {
for (i__ = j - 1; i__ >= 2; --i__) {
i__2 = i__ + j * a_dim1;
i__3 = i__ - 1 + j * a_dim1;
a[i__2].r = a[i__3].r, a[i__2].i = a[i__3].i;
/* L50: */
}
i__2 = j * a_dim1 + 1;
a[i__2].r = 0.f, a[i__2].i = 0.f;
/* L60: */
}
if (*n > 1) {
/* Form P'(2:n,2:n) */
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
cunglq_(&i__1, &i__2, &i__3, &a[(a_dim1 << 1) + 2], lda, &tau[
1], &work[1], lwork, &iinfo);
}
}
}
work[1].r = (real) lwkopt, work[1].i = 0.f;
return 0;
/* End of CUNGBR */
} /* cungbr_ */
