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/* zungtr.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 zungtr_(char *uplo, integer *n, doublecomplex *a,
integer *lda, doublecomplex *tau, doublecomplex *work, integer *lwork,
integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3, i__4;
/* Local variables */
integer i__, j, nb;
extern logical lsame_(char *, char *);
integer iinfo;
logical upper;
extern /* Subroutine */ int xerbla_(char *, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
integer lwkopt;
logical lquery;
extern /* Subroutine */ int zungql_(integer *, integer *, integer *,
doublecomplex *, integer *, doublecomplex *, doublecomplex *,
integer *, integer *), zungqr_(integer *, integer *, integer *,
doublecomplex *, integer *, doublecomplex *, doublecomplex *,
integer *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* ZUNGTR generates a complex unitary matrix Q which is defined as the */
/* product of n-1 elementary reflectors of order N, as returned by */
/* ZHETRD: */
/* 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 ZHETRD; */
/* = 'L': Lower triangle of A contains elementary reflectors */
/* from ZHETRD. */
/* N (input) INTEGER */
/* The order of the matrix Q. N >= 0. */
/* A (input/output) COMPLEX*16 array, dimension (LDA,N) */
/* On entry, the vectors which define the elementary reflectors, */
/* as returned by ZHETRD. */
/* On exit, the N-by-N unitary matrix Q. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= N. */
/* TAU (input) COMPLEX*16 array, dimension (N-1) */
/* TAU(i) must contain the scalar factor of the elementary */
/* reflector H(i), as returned by ZHETRD. */
/* WORK (workspace/output) COMPLEX*16 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 >= 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");
if (! upper && ! lsame_(uplo, "L")) {
*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, "ZUNGQL", " ", &i__1, &i__2, &i__3, &c_n1);
} else {
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
nb = ilaenv_(&c__1, "ZUNGQR", " ", &i__1, &i__2, &i__3, &c_n1);
}
/* Computing MAX */
i__1 = 1, i__2 = *n - 1;
lwkopt = max(i__1,i__2) * nb;
work[1].r = (doublereal) lwkopt, work[1].i = 0.;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("ZUNGTR", &i__1);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible */
if (*n == 0) {
work[1].r = 1., work[1].i = 0.;
return 0;
}
if (upper) {
/* Q was determined by a call to ZHETRD 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__) {
i__3 = i__ + j * a_dim1;
i__4 = i__ + (j + 1) * a_dim1;
a[i__3].r = a[i__4].r, a[i__3].i = a[i__4].i;
/* L10: */
}
i__2 = *n + j * a_dim1;
a[i__2].r = 0., a[i__2].i = 0.;
/* L20: */
}
i__1 = *n - 1;
for (i__ = 1; i__ <= i__1; ++i__) {
i__2 = i__ + *n * a_dim1;
a[i__2].r = 0., a[i__2].i = 0.;
/* L30: */
}
i__1 = *n + *n * a_dim1;
a[i__1].r = 1., a[i__1].i = 0.;
/* Generate Q(1:n-1,1:n-1) */
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
zungql_(&i__1, &i__2, &i__3, &a[a_offset], lda, &tau[1], &work[1],
lwork, &iinfo);
} else {
/* Q was determined by a call to ZHETRD 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) {
i__1 = j * a_dim1 + 1;
a[i__1].r = 0., a[i__1].i = 0.;
i__1 = *n;
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;
/* L40: */
}
/* L50: */
}
i__1 = a_dim1 + 1;
a[i__1].r = 1., a[i__1].i = 0.;
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
i__2 = i__ + a_dim1;
a[i__2].r = 0., a[i__2].i = 0.;
/* L60: */
}
if (*n > 1) {
/* Generate Q(2:n,2:n) */
i__1 = *n - 1;
i__2 = *n - 1;
i__3 = *n - 1;
zungqr_(&i__1, &i__2, &i__3, &a[(a_dim1 << 1) + 2], lda, &tau[1],
&work[1], lwork, &iinfo);
}
}
work[1].r = (doublereal) lwkopt, work[1].i = 0.;
return 0;
/* End of ZUNGTR */
} /* zungtr_ */
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