/* Subroutine */
int zheevx_(char *jobz, char *range, char *uplo, integer *n, doublecomplex *a, integer *lda, doublereal *vl, doublereal *vu, integer *il, integer *iu, doublereal *abstol, integer *m, doublereal * w, doublecomplex *z__, integer *ldz, doublecomplex *work, integer * lwork, doublereal *rwork, integer *iwork, integer *ifail, integer * info)
{
/* System generated locals */
integer a_dim1, a_offset, z_dim1, z_offset, i__1, i__2;
doublereal d__1, d__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__, j, nb, jj;
doublereal eps, vll, vuu, tmp1;
integer indd, inde;
doublereal anrm;
integer imax;
doublereal rmin, rmax;
logical test;
integer itmp1, indee;
extern /* Subroutine */
int dscal_(integer *, doublereal *, doublereal *, integer *);
doublereal sigma;
extern logical lsame_(char *, char *);
integer iinfo;
char order[1];
extern /* Subroutine */
int dcopy_(integer *, doublereal *, integer *, doublereal *, integer *);
logical lower, wantz;
extern /* Subroutine */
int zswap_(integer *, doublecomplex *, integer *, doublecomplex *, integer *);
extern doublereal dlamch_(char *);
logical alleig, indeig;
integer iscale, indibl;
logical valeig;
doublereal safmin;
extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *);
extern /* Subroutine */
int xerbla_(char *, integer *), zdscal_( integer *, doublereal *, doublecomplex *, integer *);
doublereal abstll, bignum;
extern doublereal zlanhe_(char *, char *, integer *, doublecomplex *, integer *, doublereal *);
integer indiwk, indisp, indtau;
extern /* Subroutine */
int dsterf_(integer *, doublereal *, doublereal *, integer *), dstebz_(char *, char *, integer *, doublereal *, doublereal *, integer *, integer *, doublereal *, doublereal *, doublereal *, integer *, integer *, doublereal *, integer *, integer *, doublereal *, integer *, integer *);
integer indrwk, indwrk;
extern /* Subroutine */
int zhetrd_(char *, integer *, doublecomplex *, integer *, doublereal *, doublereal *, doublecomplex *, doublecomplex *, integer *, integer *);
integer lwkmin;
extern /* Subroutine */
int zlacpy_(char *, integer *, integer *, doublecomplex *, integer *, doublecomplex *, integer *);
integer llwork, nsplit;
doublereal smlnum;
extern /* Subroutine */
int zstein_(integer *, doublereal *, doublereal *, integer *, doublereal *, integer *, integer *, doublecomplex *, integer *, doublereal *, integer *, integer *, integer *);
integer lwkopt;
logical lquery;
extern /* Subroutine */
int zsteqr_(char *, integer *, doublereal *, doublereal *, doublecomplex *, integer *, doublereal *, integer *), zungtr_(char *, integer *, doublecomplex *, integer *, doublecomplex *, doublecomplex *, integer *, integer *), zunmtr_(char *, char *, char *, integer *, integer *, doublecomplex *, integer *, doublecomplex *, doublecomplex *, integer *, doublecomplex *, integer *, integer *);
/* -- LAPACK driver routine (version 3.4.0) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* November 2011 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
--rwork;
--iwork;
--ifail;
/* Function Body */
lower = lsame_(uplo, "L");
wantz = lsame_(jobz, "V");
alleig = lsame_(range, "A");
valeig = lsame_(range, "V");
indeig = lsame_(range, "I");
lquery = *lwork == -1;
*info = 0;
if (! (wantz || lsame_(jobz, "N")))
{
*info = -1;
}
else if (! (alleig || valeig || indeig))
{
*info = -2;
}
else if (! (lower || lsame_(uplo, "U")))
{
*info = -3;
}
else if (*n < 0)
{
*info = -4;
}
else if (*lda < max(1,*n))
{
*info = -6;
}
else
{
if (valeig)
{
if (*n > 0 && *vu <= *vl)
{
*info = -8;
}
}
else if (indeig)
{
if (*il < 1 || *il > max(1,*n))
{
*info = -9;
}
else if (*iu < min(*n,*il) || *iu > *n)
{
*info = -10;
}
}
}
if (*info == 0)
{
if (*ldz < 1 || wantz && *ldz < *n)
{
*info = -15;
}
}
if (*info == 0)
{
if (*n <= 1)
{
lwkmin = 1;
work[1].r = (doublereal) lwkmin;
work[1].i = 0.; // , expr subst
}
else
{
lwkmin = *n << 1;
nb = ilaenv_(&c__1, "ZHETRD", uplo, n, &c_n1, &c_n1, &c_n1);
/* Computing MAX */
i__1 = nb;
i__2 = ilaenv_(&c__1, "ZUNMTR", uplo, n, &c_n1, &c_n1, &c_n1); // , expr subst
nb = max(i__1,i__2);
/* Computing MAX */
i__1 = 1;
i__2 = (nb + 1) * *n; // , expr subst
lwkopt = max(i__1,i__2);
work[1].r = (doublereal) lwkopt;
work[1].i = 0.; // , expr subst
}
if (*lwork < lwkmin && ! lquery)
{
*info = -17;
}
}
if (*info != 0)
{
i__1 = -(*info);
xerbla_("ZHEEVX", &i__1);
return 0;
}
else if (lquery)
{
return 0;
}
/* Quick return if possible */
*m = 0;
if (*n == 0)
{
return 0;
}
if (*n == 1)
{
if (alleig || indeig)
{
*m = 1;
i__1 = a_dim1 + 1;
w[1] = a[i__1].r;
}
else if (valeig)
{
i__1 = a_dim1 + 1;
i__2 = a_dim1 + 1;
if (*vl < a[i__1].r && *vu >= a[i__2].r)
{
*m = 1;
i__1 = a_dim1 + 1;
w[1] = a[i__1].r;
}
}
if (wantz)
{
i__1 = z_dim1 + 1;
z__[i__1].r = 1.;
z__[i__1].i = 0.; // , expr subst
}
return 0;
}
/* Get machine constants. */
safmin = dlamch_("Safe minimum");
eps = dlamch_("Precision");
smlnum = safmin / eps;
bignum = 1. / smlnum;
rmin = sqrt(smlnum);
/* Computing MIN */
d__1 = sqrt(bignum);
d__2 = 1. / sqrt(sqrt(safmin)); // , expr subst
rmax = min(d__1,d__2);
/* Scale matrix to allowable range, if necessary. */
iscale = 0;
abstll = *abstol;
if (valeig)
{
vll = *vl;
vuu = *vu;
}
anrm = zlanhe_("M", uplo, n, &a[a_offset], lda, &rwork[1]);
if (anrm > 0. && anrm < rmin)
{
iscale = 1;
sigma = rmin / anrm;
}
else if (anrm > rmax)
{
iscale = 1;
sigma = rmax / anrm;
}
if (iscale == 1)
{
if (lower)
{
i__1 = *n;
for (j = 1;
j <= i__1;
++j)
{
i__2 = *n - j + 1;
zdscal_(&i__2, &sigma, &a[j + j * a_dim1], &c__1);
/* L10: */
}
}
else
{
i__1 = *n;
for (j = 1;
j <= i__1;
++j)
{
zdscal_(&j, &sigma, &a[j * a_dim1 + 1], &c__1);
/* L20: */
}
}
if (*abstol > 0.)
{
abstll = *abstol * sigma;
}
if (valeig)
{
vll = *vl * sigma;
vuu = *vu * sigma;
}
}
/* Call ZHETRD to reduce Hermitian matrix to tridiagonal form. */
indd = 1;
inde = indd + *n;
indrwk = inde + *n;
indtau = 1;
indwrk = indtau + *n;
llwork = *lwork - indwrk + 1;
zhetrd_(uplo, n, &a[a_offset], lda, &rwork[indd], &rwork[inde], &work[ indtau], &work[indwrk], &llwork, &iinfo);
/* If all eigenvalues are desired and ABSTOL is less than or equal to */
/* zero, then call DSTERF or ZUNGTR and ZSTEQR. If this fails for */
/* some eigenvalue, then try DSTEBZ. */
test = FALSE_;
if (indeig)
{
if (*il == 1 && *iu == *n)
{
test = TRUE_;
}
}
if ((alleig || test) && *abstol <= 0.)
{
dcopy_(n, &rwork[indd], &c__1, &w[1], &c__1);
indee = indrwk + (*n << 1);
if (! wantz)
{
i__1 = *n - 1;
dcopy_(&i__1, &rwork[inde], &c__1, &rwork[indee], &c__1);
dsterf_(n, &w[1], &rwork[indee], info);
}
else
{
zlacpy_("A", n, n, &a[a_offset], lda, &z__[z_offset], ldz);
zungtr_(uplo, n, &z__[z_offset], ldz, &work[indtau], &work[indwrk] , &llwork, &iinfo);
i__1 = *n - 1;
dcopy_(&i__1, &rwork[inde], &c__1, &rwork[indee], &c__1);
zsteqr_(jobz, n, &w[1], &rwork[indee], &z__[z_offset], ldz, & rwork[indrwk], info);
if (*info == 0)
{
i__1 = *n;
for (i__ = 1;
i__ <= i__1;
++i__)
{
ifail[i__] = 0;
/* L30: */
}
}
}
if (*info == 0)
{
*m = *n;
goto L40;
}
*info = 0;
}
/* Otherwise, call DSTEBZ and, if eigenvectors are desired, ZSTEIN. */
if (wantz)
{
*(unsigned char *)order = 'B';
}
else
{
*(unsigned char *)order = 'E';
}
indibl = 1;
indisp = indibl + *n;
indiwk = indisp + *n;
dstebz_(range, order, n, &vll, &vuu, il, iu, &abstll, &rwork[indd], & rwork[inde], m, &nsplit, &w[1], &iwork[indibl], &iwork[indisp], & rwork[indrwk], &iwork[indiwk], info);
if (wantz)
{
zstein_(n, &rwork[indd], &rwork[inde], m, &w[1], &iwork[indibl], & iwork[indisp], &z__[z_offset], ldz, &rwork[indrwk], &iwork[ indiwk], &ifail[1], info);
/* Apply unitary matrix used in reduction to tridiagonal */
/* form to eigenvectors returned by ZSTEIN. */
zunmtr_("L", uplo, "N", n, m, &a[a_offset], lda, &work[indtau], &z__[ z_offset], ldz, &work[indwrk], &llwork, &iinfo);
}
/* If matrix was scaled, then rescale eigenvalues appropriately. */
L40:
if (iscale == 1)
{
if (*info == 0)
{
imax = *m;
}
else
{
imax = *info - 1;
}
d__1 = 1. / sigma;
dscal_(&imax, &d__1, &w[1], &c__1);
}
/* If eigenvalues are not in order, then sort them, along with */
/* eigenvectors. */
if (wantz)
{
i__1 = *m - 1;
for (j = 1;
j <= i__1;
++j)
{
i__ = 0;
tmp1 = w[j];
i__2 = *m;
for (jj = j + 1;
jj <= i__2;
++jj)
{
if (w[jj] < tmp1)
{
i__ = jj;
tmp1 = w[jj];
}
/* L50: */
}
if (i__ != 0)
{
itmp1 = iwork[indibl + i__ - 1];
w[i__] = w[j];
iwork[indibl + i__ - 1] = iwork[indibl + j - 1];
w[j] = tmp1;
iwork[indibl + j - 1] = itmp1;
zswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[j * z_dim1 + 1], &c__1);
if (*info != 0)
{
itmp1 = ifail[i__];
ifail[i__] = ifail[j];
ifail[j] = itmp1;
}
}
/* L60: */
}
}
/* Set WORK(1) to optimal complex workspace size. */
work[1].r = (doublereal) lwkopt;
work[1].i = 0.; // , expr subst
return 0;
/* End of ZHEEVX */
}
/* Subroutine */ int zheevx_(char *jobz, char *range, char *uplo, integer *n,
doublecomplex *a, integer *lda, doublereal *vl, doublereal *vu,
integer *il, integer *iu, doublereal *abstol, integer *m, doublereal *
w, doublecomplex *z, integer *ldz, doublecomplex *work, integer *
lwork, doublereal *rwork, integer *iwork, integer *ifail, integer *
info)
{
/* -- LAPACK driver routine (version 2.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
September 30, 1994
Purpose
=======
ZHEEVX computes selected eigenvalues and, optionally, eigenvectors
of a complex Hermitian matrix A. Eigenvalues and eigenvectors can
be selected by specifying either a range of values or a range of
indices for the desired eigenvalues.
Arguments
=========
JOBZ (input) CHARACTER*1
= 'N': Compute eigenvalues only;
= 'V': Compute eigenvalues and eigenvectors.
RANGE (input) CHARACTER*1
= 'A': all eigenvalues will be found.
= 'V': all eigenvalues in the half-open interval (VL,VU]
will be found.
= 'I': the IL-th through IU-th eigenvalues will be found.
UPLO (input) CHARACTER*1
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
N (input) INTEGER
The order of the matrix A. N >= 0.
A (input/output) COMPLEX*16 array, dimension (LDA, N)
On entry, the Hermitian matrix A. If UPLO = 'U', the
leading N-by-N upper triangular part of A contains the
upper triangular part of the matrix A. If UPLO = 'L',
the leading N-by-N lower triangular part of A contains
the lower triangular part of the matrix A.
On exit, the lower triangle (if UPLO='L') or the upper
triangle (if UPLO='U') of A, including the diagonal, is
destroyed.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
VL (input) DOUBLE PRECISION
VU (input) DOUBLE PRECISION
If RANGE='V', the lower and upper bounds of the interval to
be searched for eigenvalues. VL < VU.
Not referenced if RANGE = 'A' or 'I'.
IL (input) INTEGER
IU (input) INTEGER
If RANGE='I', the indices (in ascending order) of the
smallest and largest eigenvalues to be returned.
1 <= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0.
Not referenced if RANGE = 'A' or 'V'.
ABSTOL (input) DOUBLE PRECISION
The absolute error tolerance for the eigenvalues.
An approximate eigenvalue is accepted as converged
when it is determined to lie in an interval [a,b]
of width less than or equal to
ABSTOL + EPS * max( |a|,|b| ) ,
where EPS is the machine precision. If ABSTOL is less than
or equal to zero, then EPS*|T| will be used in its place,
where |T| is the 1-norm of the tridiagonal matrix obtained
by reducing A to tridiagonal form.
Eigenvalues will be computed most accurately when ABSTOL is
set to twice the underflow threshold 2*DLAMCH('S'), not zero.
If this routine returns with INFO>0, indicating that some
eigenvectors did not converge, try setting ABSTOL to
2*DLAMCH('S').
See "Computing Small Singular Values of Bidiagonal Matrices
with Guaranteed High Relative Accuracy," by Demmel and
Kahan, LAPACK Working Note #3.
M (output) INTEGER
The total number of eigenvalues found. 0 <= M <= N.
If RANGE = 'A', M = N, and if RANGE = 'I', M = IU-IL+1.
W (output) DOUBLE PRECISION array, dimension (N)
On normal exit, the first M elements contain the selected
eigenvalues in ascending order.
Z (output) COMPLEX*16 array, dimension (LDZ, max(1,M))
If JOBZ = 'V', then if INFO = 0, the first M columns of Z
contain the orthonormal eigenvectors of the matrix A
corresponding to the selected eigenvalues, with the i-th
column of Z holding the eigenvector associated with W(i).
If an eigenvector fails to converge, then that column of Z
contains the latest approximation to the eigenvector, and the
index of the eigenvector is returned in IFAIL.
If JOBZ = 'N', then Z is not referenced.
Note: the user must ensure that at least max(1,M) columns are
supplied in the array Z; if RANGE = 'V', the exact value of M
is not known in advance and an upper bound must be used.
LDZ (input) INTEGER
The leading dimension of the array Z. LDZ >= 1, and if
JOBZ = 'V', LDZ >= max(1,N).
WORK (workspace/output) COMPLEX*16 array, dimension (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input) INTEGER
The length of the array WORK. LWORK >= max(1,2*N-1).
For optimal efficiency, LWORK >= (NB+1)*N,
where NB is the blocksize for ZHETRD returned by ILAENV.
RWORK (workspace) DOUBLE PRECISION array, dimension (7*N)
IWORK (workspace) INTEGER array, dimension (5*N)
IFAIL (output) INTEGER array, dimension (N)
If JOBZ = 'V', then if INFO = 0, the first M elements of
IFAIL are zero. If INFO > 0, then IFAIL contains the
indices of the eigenvectors that failed to converge.
If JOBZ = 'N', then IFAIL is not referenced.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, then i eigenvectors failed to converge.
Their indices are stored in array IFAIL.
=====================================================================
Test the input parameters.
Parameter adjustments
Function Body */
/* Table of constant values */
static integer c__1 = 1;
/* System generated locals */
integer a_dim1, a_offset, z_dim1, z_offset, i__1, i__2;
doublereal d__1, d__2;
doublecomplex z__1;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
static integer indd, inde;
static doublereal anrm;
static integer imax;
static doublereal rmin, rmax;
static integer lopt, itmp1, i, j, indee;
extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
integer *);
static doublereal sigma;
extern logical lsame_(char *, char *);
static integer iinfo;
static char order[1];
extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
doublereal *, integer *);
static logical lower, wantz;
extern /* Subroutine */ int zswap_(integer *, doublecomplex *, integer *,
doublecomplex *, integer *);
static integer jj;
extern doublereal dlamch_(char *);
static logical alleig, indeig;
static integer iscale, indibl;
static logical valeig;
static doublereal safmin;
extern /* Subroutine */ int xerbla_(char *, integer *), zdscal_(
integer *, doublereal *, doublecomplex *, integer *);
static doublereal abstll, bignum;
extern doublereal zlanhe_(char *, char *, integer *, doublecomplex *,
integer *, doublereal *);
static integer indiwk, indisp, indtau;
extern /* Subroutine */ int dsterf_(integer *, doublereal *, doublereal *,
integer *), dstebz_(char *, char *, integer *, doublereal *,
doublereal *, integer *, integer *, doublereal *, doublereal *,
doublereal *, integer *, integer *, doublereal *, integer *,
integer *, doublereal *, integer *, integer *);
static integer indrwk, indwrk;
extern /* Subroutine */ int zhetrd_(char *, integer *, doublecomplex *,
integer *, doublereal *, doublereal *, doublecomplex *,
doublecomplex *, integer *, integer *), zlacpy_(char *,
integer *, integer *, doublecomplex *, integer *, doublecomplex *,
integer *);
static integer llwork, nsplit;
static doublereal smlnum;
extern /* Subroutine */ int zstein_(integer *, doublereal *, doublereal *,
integer *, doublereal *, integer *, integer *, doublecomplex *,
integer *, doublereal *, integer *, integer *, integer *),
zsteqr_(char *, integer *, doublereal *, doublereal *,
doublecomplex *, integer *, doublereal *, integer *),
zungtr_(char *, integer *, doublecomplex *, integer *,
doublecomplex *, doublecomplex *, integer *, integer *),
zunmtr_(char *, char *, char *, integer *, integer *,
doublecomplex *, integer *, doublecomplex *, doublecomplex *,
integer *, doublecomplex *, integer *, integer *);
static doublereal eps, vll, vuu, tmp1;
#define W(I) w[(I)-1]
#define WORK(I) work[(I)-1]
#define RWORK(I) rwork[(I)-1]
#define IWORK(I) iwork[(I)-1]
#define IFAIL(I) ifail[(I)-1]
#define A(I,J) a[(I)-1 + ((J)-1)* ( *lda)]
#define Z(I,J) z[(I)-1 + ((J)-1)* ( *ldz)]
lower = lsame_(uplo, "L");
wantz = lsame_(jobz, "V");
alleig = lsame_(range, "A");
valeig = lsame_(range, "V");
indeig = lsame_(range, "I");
*info = 0;
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (alleig || valeig || indeig)) {
*info = -2;
} else if (! (lower || lsame_(uplo, "U"))) {
*info = -3;
} else if (*n < 0) {
*info = -4;
} else if (*lda < max(1,*n)) {
*info = -6;
} else if (valeig && *n > 0 && *vu <= *vl) {
*info = -8;
} else if (indeig && *il < 1) {
*info = -9;
} else if (indeig && (*iu < min(*n,*il) || *iu > *n)) {
*info = -10;
} else if (*ldz < 1 || wantz && *ldz < *n) {
*info = -15;
} else /* if(complicated condition) */ {
/* Computing MAX */
i__1 = 1, i__2 = (*n << 1) - 1;
if (*lwork < max(i__1,i__2)) {
*info = -17;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("ZHEEVX", &i__1);
return 0;
}
/* Quick return if possible */
*m = 0;
if (*n == 0) {
WORK(1).r = 1., WORK(1).i = 0.;
return 0;
}
if (*n == 1) {
WORK(1).r = 1., WORK(1).i = 0.;
if (alleig || indeig) {
*m = 1;
i__1 = a_dim1 + 1;
W(1) = A(1,1).r;
} else if (valeig) {
i__1 = a_dim1 + 1;
i__2 = a_dim1 + 1;
if (*vl < A(1,1).r && *vu >= A(1,1).r) {
*m = 1;
i__1 = a_dim1 + 1;
W(1) = A(1,1).r;
}
}
if (wantz) {
i__1 = z_dim1 + 1;
Z(1,1).r = 1., Z(1,1).i = 0.;
}
return 0;
}
/* Get machine constants. */
safmin = dlamch_("Safe minimum");
eps = dlamch_("Precision");
smlnum = safmin / eps;
bignum = 1. / smlnum;
rmin = sqrt(smlnum);
/* Computing MIN */
d__1 = sqrt(bignum), d__2 = 1. / sqrt(sqrt(safmin));
rmax = min(d__1,d__2);
/* Scale matrix to allowable range, if necessary. */
iscale = 0;
abstll = *abstol;
if (valeig) {
vll = *vl;
vuu = *vu;
}
anrm = zlanhe_("M", uplo, n, &A(1,1), lda, &RWORK(1));
if (anrm > 0. && anrm < rmin) {
iscale = 1;
sigma = rmin / anrm;
} else if (anrm > rmax) {
iscale = 1;
sigma = rmax / anrm;
}
if (iscale == 1) {
if (lower) {
i__1 = *n;
for (j = 1; j <= *n; ++j) {
i__2 = *n - j + 1;
zdscal_(&i__2, &sigma, &A(j,j), &c__1);
/* L10: */
}
} else {
i__1 = *n;
for (j = 1; j <= *n; ++j) {
zdscal_(&j, &sigma, &A(1,j), &c__1);
/* L20: */
}
}
if (*abstol > 0.) {
abstll = *abstol * sigma;
}
if (valeig) {
vll = *vl * sigma;
vuu = *vu * sigma;
}
}
/* Call ZHETRD to reduce Hermitian matrix to tridiagonal form. */
indd = 1;
inde = indd + *n;
indrwk = inde + *n;
indtau = 1;
indwrk = indtau + *n;
llwork = *lwork - indwrk + 1;
zhetrd_(uplo, n, &A(1,1), lda, &RWORK(indd), &RWORK(inde), &WORK(
indtau), &WORK(indwrk), &llwork, &iinfo);
i__1 = indwrk;
z__1.r = *n + WORK(indwrk).r, z__1.i = WORK(indwrk).i;
lopt = (integer) z__1.r;
/* If all eigenvalues are desired and ABSTOL is less than or equal to
zero, then call DSTERF or ZUNGTR and ZSTEQR. If this fails for
some eigenvalue, then try DSTEBZ. */
if ((alleig || indeig && *il == 1 && *iu == *n) && *abstol <= 0.) {
dcopy_(n, &RWORK(indd), &c__1, &W(1), &c__1);
indee = indrwk + (*n << 1);
if (! wantz) {
i__1 = *n - 1;
dcopy_(&i__1, &RWORK(inde), &c__1, &RWORK(indee), &c__1);
dsterf_(n, &W(1), &RWORK(indee), info);
} else {
zlacpy_("A", n, n, &A(1,1), lda, &Z(1,1), ldz);
zungtr_(uplo, n, &Z(1,1), ldz, &WORK(indtau), &WORK(indwrk),
&llwork, &iinfo);
i__1 = *n - 1;
dcopy_(&i__1, &RWORK(inde), &c__1, &RWORK(indee), &c__1);
zsteqr_(jobz, n, &W(1), &RWORK(indee), &Z(1,1), ldz, &RWORK(
indrwk), info);
if (*info == 0) {
i__1 = *n;
for (i = 1; i <= *n; ++i) {
IFAIL(i) = 0;
/* L30: */
}
}
}
if (*info == 0) {
*m = *n;
goto L40;
}
*info = 0;
}
/* Otherwise, call DSTEBZ and, if eigenvectors are desired, ZSTEIN. */
if (wantz) {
*(unsigned char *)order = 'B';
} else {
*(unsigned char *)order = 'E';
}
indibl = 1;
indisp = indibl + *n;
indiwk = indisp + *n;
dstebz_(range, order, n, &vll, &vuu, il, iu, &abstll, &RWORK(indd), &
RWORK(inde), m, &nsplit, &W(1), &IWORK(indibl), &IWORK(indisp), &
RWORK(indrwk), &IWORK(indiwk), info);
if (wantz) {
zstein_(n, &RWORK(indd), &RWORK(inde), m, &W(1), &IWORK(indibl), &
IWORK(indisp), &Z(1,1), ldz, &RWORK(indrwk), &IWORK(
indiwk), &IFAIL(1), info);
/* Apply unitary matrix used in reduction to tridiagonal
form to eigenvectors returned by ZSTEIN. */
zunmtr_("L", uplo, "N", n, m, &A(1,1), lda, &WORK(indtau), &Z(1,1), ldz, &WORK(indwrk), &llwork, &iinfo);
}
/* If matrix was scaled, then rescale eigenvalues appropriately. */
L40:
if (iscale == 1) {
if (*info == 0) {
imax = *m;
} else {
imax = *info - 1;
}
d__1 = 1. / sigma;
dscal_(&imax, &d__1, &W(1), &c__1);
}
/* If eigenvalues are not in order, then sort them, along with
eigenvectors. */
if (wantz) {
i__1 = *m - 1;
for (j = 1; j <= *m-1; ++j) {
i = 0;
tmp1 = W(j);
i__2 = *m;
for (jj = j + 1; jj <= *m; ++jj) {
if (W(jj) < tmp1) {
i = jj;
tmp1 = W(jj);
}
/* L50: */
}
if (i != 0) {
itmp1 = IWORK(indibl + i - 1);
W(i) = W(j);
IWORK(indibl + i - 1) = IWORK(indibl + j - 1);
W(j) = tmp1;
IWORK(indibl + j - 1) = itmp1;
zswap_(n, &Z(1,i), &c__1, &Z(1,j), &
c__1);
if (*info != 0) {
itmp1 = IFAIL(i);
IFAIL(i) = IFAIL(j);
IFAIL(j) = itmp1;
}
}
/* L60: */
}
}
/* Set WORK(1) to optimal complex workspace size.
Computing MAX */
i__1 = (*n << 1) - 1;
d__1 = (doublereal) max(i__1,lopt);
WORK(1).r = d__1, WORK(1).i = 0.;
return 0;
/* End of ZHEEVX */
} /* zheevx_ */
/* Subroutine */ int zhpevx_(char *jobz, char *range, char *uplo, integer *n,
doublecomplex *ap, doublereal *vl, doublereal *vu, integer *il,
integer *iu, doublereal *abstol, integer *m, doublereal *w,
doublecomplex *z__, integer *ldz, doublecomplex *work, doublereal *
rwork, integer *iwork, integer *ifail, integer *info)
{
/* System generated locals */
integer z_dim1, z_offset, i__1, i__2;
doublereal d__1, d__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__, j, jj;
doublereal eps, vll, vuu, tmp1;
integer indd, inde;
doublereal anrm;
integer imax;
doublereal rmin, rmax;
logical test;
integer itmp1, indee;
extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
integer *);
doublereal sigma;
extern logical lsame_(char *, char *);
integer iinfo;
char order[1];
extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
doublereal *, integer *);
logical wantz;
extern /* Subroutine */ int zswap_(integer *, doublecomplex *, integer *,
doublecomplex *, integer *);
extern doublereal dlamch_(char *);
logical alleig, indeig;
integer iscale, indibl;
logical valeig;
doublereal safmin;
extern /* Subroutine */ int xerbla_(char *, integer *), zdscal_(
integer *, doublereal *, doublecomplex *, integer *);
doublereal abstll, bignum;
integer indiwk, indisp, indtau;
extern /* Subroutine */ int dsterf_(integer *, doublereal *, doublereal *,
integer *), dstebz_(char *, char *, integer *, doublereal *,
doublereal *, integer *, integer *, doublereal *, doublereal *,
doublereal *, integer *, integer *, doublereal *, integer *,
integer *, doublereal *, integer *, integer *);
extern doublereal zlanhp_(char *, char *, integer *, doublecomplex *,
doublereal *);
integer indrwk, indwrk, nsplit;
doublereal smlnum;
extern /* Subroutine */ int zhptrd_(char *, integer *, doublecomplex *,
doublereal *, doublereal *, doublecomplex *, integer *),
zstein_(integer *, doublereal *, doublereal *, integer *,
doublereal *, integer *, integer *, doublecomplex *, integer *,
doublereal *, integer *, integer *, integer *), zsteqr_(char *,
integer *, doublereal *, doublereal *, doublecomplex *, integer *,
doublereal *, integer *), zupgtr_(char *, integer *,
doublecomplex *, doublecomplex *, doublecomplex *, integer *,
doublecomplex *, integer *), zupmtr_(char *, char *, char
*, integer *, integer *, doublecomplex *, doublecomplex *,
doublecomplex *, integer *, doublecomplex *, integer *);
/* -- LAPACK driver routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* ZHPEVX computes selected eigenvalues and, optionally, eigenvectors */
/* of a complex Hermitian matrix A in packed storage. */
/* Eigenvalues/vectors can be selected by specifying either a range of */
/* values or a range of indices for the desired eigenvalues. */
/* Arguments */
/* ========= */
/* JOBZ (input) CHARACTER*1 */
/* = 'N': Compute eigenvalues only; */
/* = 'V': Compute eigenvalues and eigenvectors. */
/* RANGE (input) CHARACTER*1 */
/* = 'A': all eigenvalues will be found; */
/* = 'V': all eigenvalues in the half-open interval (VL,VU] */
/* will be found; */
/* = 'I': the IL-th through IU-th eigenvalues will be found. */
/* UPLO (input) CHARACTER*1 */
/* = 'U': Upper triangle of A is stored; */
/* = 'L': Lower triangle of A is stored. */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. */
/* AP (input/output) COMPLEX*16 array, dimension (N*(N+1)/2) */
/* On entry, the upper or lower triangle of the Hermitian matrix */
/* A, packed columnwise in a linear array. The j-th column of A */
/* is stored in the array AP as follows: */
/* if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; */
/* if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n. */
/* On exit, AP is overwritten by values generated during the */
/* reduction to tridiagonal form. If UPLO = 'U', the diagonal */
/* and first superdiagonal of the tridiagonal matrix T overwrite */
/* the corresponding elements of A, and if UPLO = 'L', the */
/* diagonal and first subdiagonal of T overwrite the */
/* corresponding elements of A. */
/* VL (input) DOUBLE PRECISION */
/* VU (input) DOUBLE PRECISION */
/* If RANGE='V', the lower and upper bounds of the interval to */
/* be searched for eigenvalues. VL < VU. */
/* Not referenced if RANGE = 'A' or 'I'. */
/* IL (input) INTEGER */
/* IU (input) INTEGER */
/* If RANGE='I', the indices (in ascending order) of the */
/* smallest and largest eigenvalues to be returned. */
/* 1 <= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0. */
/* Not referenced if RANGE = 'A' or 'V'. */
/* ABSTOL (input) DOUBLE PRECISION */
/* The absolute error tolerance for the eigenvalues. */
/* An approximate eigenvalue is accepted as converged */
/* when it is determined to lie in an interval [a,b] */
/* of width less than or equal to */
/* ABSTOL + EPS * max( |a|,|b| ) , */
/* where EPS is the machine precision. If ABSTOL is less than */
/* or equal to zero, then EPS*|T| will be used in its place, */
/* where |T| is the 1-norm of the tridiagonal matrix obtained */
/* by reducing AP to tridiagonal form. */
/* Eigenvalues will be computed most accurately when ABSTOL is */
/* set to twice the underflow threshold 2*DLAMCH('S'), not zero. */
/* If this routine returns with INFO>0, indicating that some */
/* eigenvectors did not converge, try setting ABSTOL to */
/* 2*DLAMCH('S'). */
/* See "Computing Small Singular Values of Bidiagonal Matrices */
/* with Guaranteed High Relative Accuracy," by Demmel and */
/* Kahan, LAPACK Working Note #3. */
/* M (output) INTEGER */
/* The total number of eigenvalues found. 0 <= M <= N. */
/* If RANGE = 'A', M = N, and if RANGE = 'I', M = IU-IL+1. */
/* W (output) DOUBLE PRECISION array, dimension (N) */
/* If INFO = 0, the selected eigenvalues in ascending order. */
/* Z (output) COMPLEX*16 array, dimension (LDZ, max(1,M)) */
/* If JOBZ = 'V', then if INFO = 0, the first M columns of Z */
/* contain the orthonormal eigenvectors of the matrix A */
/* corresponding to the selected eigenvalues, with the i-th */
/* column of Z holding the eigenvector associated with W(i). */
/* If an eigenvector fails to converge, then that column of Z */
/* contains the latest approximation to the eigenvector, and */
/* the index of the eigenvector is returned in IFAIL. */
/* If JOBZ = 'N', then Z is not referenced. */
/* Note: the user must ensure that at least max(1,M) columns are */
/* supplied in the array Z; if RANGE = 'V', the exact value of M */
/* is not known in advance and an upper bound must be used. */
/* LDZ (input) INTEGER */
/* The leading dimension of the array Z. LDZ >= 1, and if */
/* JOBZ = 'V', LDZ >= max(1,N). */
/* WORK (workspace) COMPLEX*16 array, dimension (2*N) */
/* RWORK (workspace) DOUBLE PRECISION array, dimension (7*N) */
/* IWORK (workspace) INTEGER array, dimension (5*N) */
/* IFAIL (output) INTEGER array, dimension (N) */
/* If JOBZ = 'V', then if INFO = 0, the first M elements of */
/* IFAIL are zero. If INFO > 0, then IFAIL contains the */
/* indices of the eigenvectors that failed to converge. */
/* If JOBZ = 'N', then IFAIL is not referenced. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* > 0: if INFO = i, then i eigenvectors failed to converge. */
/* Their indices are stored in array IFAIL. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
--ap;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
--rwork;
--iwork;
--ifail;
/* Function Body */
wantz = lsame_(jobz, "V");
alleig = lsame_(range, "A");
valeig = lsame_(range, "V");
indeig = lsame_(range, "I");
*info = 0;
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (alleig || valeig || indeig)) {
*info = -2;
} else if (! (lsame_(uplo, "L") || lsame_(uplo,
"U"))) {
*info = -3;
} else if (*n < 0) {
*info = -4;
} else {
if (valeig) {
if (*n > 0 && *vu <= *vl) {
*info = -7;
}
} else if (indeig) {
if (*il < 1 || *il > max(1,*n)) {
*info = -8;
} else if (*iu < min(*n,*il) || *iu > *n) {
*info = -9;
}
}
}
if (*info == 0) {
if (*ldz < 1 || wantz && *ldz < *n) {
*info = -14;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("ZHPEVX", &i__1);
return 0;
}
/* Quick return if possible */
*m = 0;
if (*n == 0) {
return 0;
}
if (*n == 1) {
if (alleig || indeig) {
*m = 1;
w[1] = ap[1].r;
} else {
if (*vl < ap[1].r && *vu >= ap[1].r) {
*m = 1;
w[1] = ap[1].r;
}
}
if (wantz) {
i__1 = z_dim1 + 1;
z__[i__1].r = 1., z__[i__1].i = 0.;
}
return 0;
}
/* Get machine constants. */
safmin = dlamch_("Safe minimum");
eps = dlamch_("Precision");
smlnum = safmin / eps;
bignum = 1. / smlnum;
rmin = sqrt(smlnum);
/* Computing MIN */
d__1 = sqrt(bignum), d__2 = 1. / sqrt(sqrt(safmin));
rmax = min(d__1,d__2);
/* Scale matrix to allowable range, if necessary. */
iscale = 0;
abstll = *abstol;
if (valeig) {
vll = *vl;
vuu = *vu;
} else {
vll = 0.;
vuu = 0.;
}
anrm = zlanhp_("M", uplo, n, &ap[1], &rwork[1]);
if (anrm > 0. && anrm < rmin) {
iscale = 1;
sigma = rmin / anrm;
} else if (anrm > rmax) {
iscale = 1;
sigma = rmax / anrm;
}
if (iscale == 1) {
i__1 = *n * (*n + 1) / 2;
zdscal_(&i__1, &sigma, &ap[1], &c__1);
if (*abstol > 0.) {
abstll = *abstol * sigma;
}
if (valeig) {
vll = *vl * sigma;
vuu = *vu * sigma;
}
}
/* Call ZHPTRD to reduce Hermitian packed matrix to tridiagonal form. */
indd = 1;
inde = indd + *n;
indrwk = inde + *n;
indtau = 1;
indwrk = indtau + *n;
zhptrd_(uplo, n, &ap[1], &rwork[indd], &rwork[inde], &work[indtau], &
iinfo);
/* If all eigenvalues are desired and ABSTOL is less than or equal */
/* to zero, then call DSTERF or ZUPGTR and ZSTEQR. If this fails */
/* for some eigenvalue, then try DSTEBZ. */
test = FALSE_;
if (indeig) {
if (*il == 1 && *iu == *n) {
test = TRUE_;
}
}
if ((alleig || test) && *abstol <= 0.) {
dcopy_(n, &rwork[indd], &c__1, &w[1], &c__1);
indee = indrwk + (*n << 1);
if (! wantz) {
i__1 = *n - 1;
dcopy_(&i__1, &rwork[inde], &c__1, &rwork[indee], &c__1);
dsterf_(n, &w[1], &rwork[indee], info);
} else {
zupgtr_(uplo, n, &ap[1], &work[indtau], &z__[z_offset], ldz, &
work[indwrk], &iinfo);
i__1 = *n - 1;
dcopy_(&i__1, &rwork[inde], &c__1, &rwork[indee], &c__1);
zsteqr_(jobz, n, &w[1], &rwork[indee], &z__[z_offset], ldz, &
rwork[indrwk], info);
if (*info == 0) {
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
ifail[i__] = 0;
/* L10: */
}
}
}
if (*info == 0) {
*m = *n;
goto L20;
}
*info = 0;
}
/* Otherwise, call DSTEBZ and, if eigenvectors are desired, ZSTEIN. */
if (wantz) {
*(unsigned char *)order = 'B';
} else {
*(unsigned char *)order = 'E';
}
indibl = 1;
indisp = indibl + *n;
indiwk = indisp + *n;
dstebz_(range, order, n, &vll, &vuu, il, iu, &abstll, &rwork[indd], &
rwork[inde], m, &nsplit, &w[1], &iwork[indibl], &iwork[indisp], &
rwork[indrwk], &iwork[indiwk], info);
if (wantz) {
zstein_(n, &rwork[indd], &rwork[inde], m, &w[1], &iwork[indibl], &
iwork[indisp], &z__[z_offset], ldz, &rwork[indrwk], &iwork[
indiwk], &ifail[1], info);
/* Apply unitary matrix used in reduction to tridiagonal */
/* form to eigenvectors returned by ZSTEIN. */
indwrk = indtau + *n;
zupmtr_("L", uplo, "N", n, m, &ap[1], &work[indtau], &z__[z_offset],
ldz, &work[indwrk], &iinfo);
}
/* If matrix was scaled, then rescale eigenvalues appropriately. */
L20:
if (iscale == 1) {
if (*info == 0) {
imax = *m;
} else {
imax = *info - 1;
}
d__1 = 1. / sigma;
dscal_(&imax, &d__1, &w[1], &c__1);
}
/* If eigenvalues are not in order, then sort them, along with */
/* eigenvectors. */
if (wantz) {
i__1 = *m - 1;
for (j = 1; j <= i__1; ++j) {
i__ = 0;
tmp1 = w[j];
i__2 = *m;
for (jj = j + 1; jj <= i__2; ++jj) {
if (w[jj] < tmp1) {
i__ = jj;
tmp1 = w[jj];
}
/* L30: */
}
if (i__ != 0) {
itmp1 = iwork[indibl + i__ - 1];
w[i__] = w[j];
iwork[indibl + i__ - 1] = iwork[indibl + j - 1];
w[j] = tmp1;
iwork[indibl + j - 1] = itmp1;
zswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[j * z_dim1 + 1],
&c__1);
if (*info != 0) {
itmp1 = ifail[i__];
ifail[i__] = ifail[j];
ifail[j] = itmp1;
}
}
/* L40: */
}
}
return 0;
/* End of ZHPEVX */
} /* zhpevx_ */
/* Subroutine */ int zhbgvx_(char *jobz, char *range, char *uplo, integer *n,
integer *ka, integer *kb, doublecomplex *ab, integer *ldab,
doublecomplex *bb, integer *ldbb, doublecomplex *q, integer *ldq,
doublereal *vl, doublereal *vu, integer *il, integer *iu, doublereal *
abstol, integer *m, doublereal *w, doublecomplex *z__, integer *ldz,
doublecomplex *work, doublereal *rwork, integer *iwork, integer *
ifail, integer *info)
{
/* System generated locals */
integer ab_dim1, ab_offset, bb_dim1, bb_offset, q_dim1, q_offset, z_dim1,
z_offset, i__1, i__2;
/* Local variables */
integer i__, j, jj;
doublereal tmp1;
integer indd, inde;
char vect[1];
logical test;
integer itmp1, indee;
extern logical lsame_(char *, char *);
integer iinfo;
char order[1];
extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
doublereal *, integer *), zgemv_(char *, integer *, integer *,
doublecomplex *, doublecomplex *, integer *, doublecomplex *,
integer *, doublecomplex *, doublecomplex *, integer *);
logical upper, wantz;
extern /* Subroutine */ int zcopy_(integer *, doublecomplex *, integer *,
doublecomplex *, integer *), zswap_(integer *, doublecomplex *,
integer *, doublecomplex *, integer *);
logical alleig, indeig;
integer indibl;
logical valeig;
extern /* Subroutine */ int xerbla_(char *, integer *);
integer indiwk, indisp;
extern /* Subroutine */ int dsterf_(integer *, doublereal *, doublereal *,
integer *), dstebz_(char *, char *, integer *, doublereal *,
doublereal *, integer *, integer *, doublereal *, doublereal *,
doublereal *, integer *, integer *, doublereal *, integer *,
integer *, doublereal *, integer *, integer *),
zhbtrd_(char *, char *, integer *, integer *, doublecomplex *,
integer *, doublereal *, doublereal *, doublecomplex *, integer *,
doublecomplex *, integer *);
integer indrwk, indwrk;
extern /* Subroutine */ int zhbgst_(char *, char *, integer *, integer *,
integer *, doublecomplex *, integer *, doublecomplex *, integer *,
doublecomplex *, integer *, doublecomplex *, doublereal *,
integer *), zlacpy_(char *, integer *, integer *,
doublecomplex *, integer *, doublecomplex *, integer *);
integer nsplit;
extern /* Subroutine */ int zpbstf_(char *, integer *, integer *,
doublecomplex *, integer *, integer *), zstein_(integer *,
doublereal *, doublereal *, integer *, doublereal *, integer *,
integer *, doublecomplex *, integer *, doublereal *, integer *,
integer *, integer *), zsteqr_(char *, integer *, doublereal *,
doublereal *, doublecomplex *, integer *, doublereal *, integer *);
/* -- LAPACK driver routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* ZHBGVX computes all the eigenvalues, and optionally, the eigenvectors */
/* of a complex generalized Hermitian-definite banded eigenproblem, of */
/* the form A*x=(lambda)*B*x. Here A and B are assumed to be Hermitian */
/* and banded, and B is also positive definite. Eigenvalues and */
/* eigenvectors can be selected by specifying either all eigenvalues, */
/* a range of values or a range of indices for the desired eigenvalues. */
/* Arguments */
/* ========= */
/* JOBZ (input) CHARACTER*1 */
/* = 'N': Compute eigenvalues only; */
/* = 'V': Compute eigenvalues and eigenvectors. */
/* RANGE (input) CHARACTER*1 */
/* = 'A': all eigenvalues will be found; */
/* = 'V': all eigenvalues in the half-open interval (VL,VU] */
/* will be found; */
/* = 'I': the IL-th through IU-th eigenvalues will be found. */
/* UPLO (input) CHARACTER*1 */
/* = 'U': Upper triangles of A and B are stored; */
/* = 'L': Lower triangles of A and B are stored. */
/* N (input) INTEGER */
/* The order of the matrices A and B. N >= 0. */
/* KA (input) INTEGER */
/* The number of superdiagonals of the matrix A if UPLO = 'U', */
/* or the number of subdiagonals if UPLO = 'L'. KA >= 0. */
/* KB (input) INTEGER */
/* The number of superdiagonals of the matrix B if UPLO = 'U', */
/* or the number of subdiagonals if UPLO = 'L'. KB >= 0. */
/* AB (input/output) COMPLEX*16 array, dimension (LDAB, N) */
/* On entry, the upper or lower triangle of the Hermitian band */
/* matrix A, stored in the first ka+1 rows of the array. The */
/* j-th column of A is stored in the j-th column of the array AB */
/* as follows: */
/* if UPLO = 'U', AB(ka+1+i-j,j) = A(i,j) for max(1,j-ka)<=i<=j; */
/* if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+ka). */
/* On exit, the contents of AB are destroyed. */
/* LDAB (input) INTEGER */
/* The leading dimension of the array AB. LDAB >= KA+1. */
/* BB (input/output) COMPLEX*16 array, dimension (LDBB, N) */
/* On entry, the upper or lower triangle of the Hermitian band */
/* matrix B, stored in the first kb+1 rows of the array. The */
/* j-th column of B is stored in the j-th column of the array BB */
/* as follows: */
/* if UPLO = 'U', BB(kb+1+i-j,j) = B(i,j) for max(1,j-kb)<=i<=j; */
/* if UPLO = 'L', BB(1+i-j,j) = B(i,j) for j<=i<=min(n,j+kb). */
/* On exit, the factor S from the split Cholesky factorization */
/* B = S**H*S, as returned by ZPBSTF. */
/* LDBB (input) INTEGER */
/* The leading dimension of the array BB. LDBB >= KB+1. */
/* Q (output) COMPLEX*16 array, dimension (LDQ, N) */
/* If JOBZ = 'V', the n-by-n matrix used in the reduction of */
/* A*x = (lambda)*B*x to standard form, i.e. C*x = (lambda)*x, */
/* and consequently C to tridiagonal form. */
/* If JOBZ = 'N', the array Q is not referenced. */
/* LDQ (input) INTEGER */
/* The leading dimension of the array Q. If JOBZ = 'N', */
/* LDQ >= 1. If JOBZ = 'V', LDQ >= max(1,N). */
/* VL (input) DOUBLE PRECISION */
/* VU (input) DOUBLE PRECISION */
/* If RANGE='V', the lower and upper bounds of the interval to */
/* be searched for eigenvalues. VL < VU. */
/* Not referenced if RANGE = 'A' or 'I'. */
/* IL (input) INTEGER */
/* IU (input) INTEGER */
/* If RANGE='I', the indices (in ascending order) of the */
/* smallest and largest eigenvalues to be returned. */
/* 1 <= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0. */
/* Not referenced if RANGE = 'A' or 'V'. */
/* ABSTOL (input) DOUBLE PRECISION */
/* The absolute error tolerance for the eigenvalues. */
/* An approximate eigenvalue is accepted as converged */
/* when it is determined to lie in an interval [a,b] */
/* of width less than or equal to */
/* ABSTOL + EPS * max( |a|,|b| ) , */
/* where EPS is the machine precision. If ABSTOL is less than */
/* or equal to zero, then EPS*|T| will be used in its place, */
/* where |T| is the 1-norm of the tridiagonal matrix obtained */
/* by reducing AP to tridiagonal form. */
/* Eigenvalues will be computed most accurately when ABSTOL is */
/* set to twice the underflow threshold 2*DLAMCH('S'), not zero. */
/* If this routine returns with INFO>0, indicating that some */
/* eigenvectors did not converge, try setting ABSTOL to */
/* 2*DLAMCH('S'). */
/* M (output) INTEGER */
/* The total number of eigenvalues found. 0 <= M <= N. */
/* If RANGE = 'A', M = N, and if RANGE = 'I', M = IU-IL+1. */
/* W (output) DOUBLE PRECISION array, dimension (N) */
/* If INFO = 0, the eigenvalues in ascending order. */
/* Z (output) COMPLEX*16 array, dimension (LDZ, N) */
/* If JOBZ = 'V', then if INFO = 0, Z contains the matrix Z of */
/* eigenvectors, with the i-th column of Z holding the */
/* eigenvector associated with W(i). The eigenvectors are */
/* normalized so that Z**H*B*Z = I. */
/* If JOBZ = 'N', then Z is not referenced. */
/* LDZ (input) INTEGER */
/* The leading dimension of the array Z. LDZ >= 1, and if */
/* JOBZ = 'V', LDZ >= N. */
/* WORK (workspace) COMPLEX*16 array, dimension (N) */
/* RWORK (workspace) DOUBLE PRECISION array, dimension (7*N) */
/* IWORK (workspace) INTEGER array, dimension (5*N) */
/* IFAIL (output) INTEGER array, dimension (N) */
/* If JOBZ = 'V', then if INFO = 0, the first M elements of */
/* IFAIL are zero. If INFO > 0, then IFAIL contains the */
/* indices of the eigenvectors that failed to converge. */
/* If JOBZ = 'N', then IFAIL is not referenced. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* > 0: if INFO = i, and i is: */
/* <= N: then i eigenvectors failed to converge. Their */
/* indices are stored in array IFAIL. */
/* > N: if INFO = N + i, for 1 <= i <= N, then ZPBSTF */
/* returned INFO = i: B is not positive definite. */
/* The factorization of B could not be completed and */
/* no eigenvalues or eigenvectors were computed. */
/* Further Details */
/* =============== */
/* Based on contributions by */
/* Mark Fahey, Department of Mathematics, Univ. of Kentucky, USA */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
ab_dim1 = *ldab;
ab_offset = 1 + ab_dim1;
ab -= ab_offset;
bb_dim1 = *ldbb;
bb_offset = 1 + bb_dim1;
bb -= bb_offset;
q_dim1 = *ldq;
q_offset = 1 + q_dim1;
q -= q_offset;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
--rwork;
--iwork;
--ifail;
/* Function Body */
wantz = lsame_(jobz, "V");
upper = lsame_(uplo, "U");
alleig = lsame_(range, "A");
valeig = lsame_(range, "V");
indeig = lsame_(range, "I");
*info = 0;
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (alleig || valeig || indeig)) {
*info = -2;
} else if (! (upper || lsame_(uplo, "L"))) {
*info = -3;
} else if (*n < 0) {
*info = -4;
} else if (*ka < 0) {
*info = -5;
} else if (*kb < 0 || *kb > *ka) {
*info = -6;
} else if (*ldab < *ka + 1) {
*info = -8;
} else if (*ldbb < *kb + 1) {
*info = -10;
} else if (*ldq < 1 || wantz && *ldq < *n) {
*info = -12;
} else {
if (valeig) {
if (*n > 0 && *vu <= *vl) {
*info = -14;
}
} else if (indeig) {
if (*il < 1 || *il > max(1,*n)) {
*info = -15;
} else if (*iu < min(*n,*il) || *iu > *n) {
*info = -16;
}
}
}
if (*info == 0) {
if (*ldz < 1 || wantz && *ldz < *n) {
*info = -21;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("ZHBGVX", &i__1);
return 0;
}
/* Quick return if possible */
*m = 0;
if (*n == 0) {
return 0;
}
/* Form a split Cholesky factorization of B. */
zpbstf_(uplo, n, kb, &bb[bb_offset], ldbb, info);
if (*info != 0) {
*info = *n + *info;
return 0;
}
/* Transform problem to standard eigenvalue problem. */
zhbgst_(jobz, uplo, n, ka, kb, &ab[ab_offset], ldab, &bb[bb_offset], ldbb,
&q[q_offset], ldq, &work[1], &rwork[1], &iinfo);
/* Solve the standard eigenvalue problem. */
/* Reduce Hermitian band matrix to tridiagonal form. */
indd = 1;
inde = indd + *n;
indrwk = inde + *n;
indwrk = 1;
if (wantz) {
*(unsigned char *)vect = 'U';
} else {
*(unsigned char *)vect = 'N';
}
zhbtrd_(vect, uplo, n, ka, &ab[ab_offset], ldab, &rwork[indd], &rwork[
inde], &q[q_offset], ldq, &work[indwrk], &iinfo);
/* If all eigenvalues are desired and ABSTOL is less than or equal */
/* to zero, then call DSTERF or ZSTEQR. If this fails for some */
/* eigenvalue, then try DSTEBZ. */
test = FALSE_;
if (indeig) {
if (*il == 1 && *iu == *n) {
test = TRUE_;
}
}
if ((alleig || test) && *abstol <= 0.) {
dcopy_(n, &rwork[indd], &c__1, &w[1], &c__1);
indee = indrwk + (*n << 1);
i__1 = *n - 1;
dcopy_(&i__1, &rwork[inde], &c__1, &rwork[indee], &c__1);
if (! wantz) {
dsterf_(n, &w[1], &rwork[indee], info);
} else {
zlacpy_("A", n, n, &q[q_offset], ldq, &z__[z_offset], ldz);
zsteqr_(jobz, n, &w[1], &rwork[indee], &z__[z_offset], ldz, &
rwork[indrwk], info);
if (*info == 0) {
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
ifail[i__] = 0;
/* L10: */
}
}
}
if (*info == 0) {
*m = *n;
goto L30;
}
*info = 0;
}
/* Otherwise, call DSTEBZ and, if eigenvectors are desired, */
/* call ZSTEIN. */
if (wantz) {
*(unsigned char *)order = 'B';
} else {
*(unsigned char *)order = 'E';
}
indibl = 1;
indisp = indibl + *n;
indiwk = indisp + *n;
dstebz_(range, order, n, vl, vu, il, iu, abstol, &rwork[indd], &rwork[
inde], m, &nsplit, &w[1], &iwork[indibl], &iwork[indisp], &rwork[
indrwk], &iwork[indiwk], info);
if (wantz) {
zstein_(n, &rwork[indd], &rwork[inde], m, &w[1], &iwork[indibl], &
iwork[indisp], &z__[z_offset], ldz, &rwork[indrwk], &iwork[
indiwk], &ifail[1], info);
/* Apply unitary matrix used in reduction to tridiagonal */
/* form to eigenvectors returned by ZSTEIN. */
i__1 = *m;
for (j = 1; j <= i__1; ++j) {
zcopy_(n, &z__[j * z_dim1 + 1], &c__1, &work[1], &c__1);
zgemv_("N", n, n, &c_b2, &q[q_offset], ldq, &work[1], &c__1, &
c_b1, &z__[j * z_dim1 + 1], &c__1);
/* L20: */
}
}
L30:
/* If eigenvalues are not in order, then sort them, along with */
/* eigenvectors. */
if (wantz) {
i__1 = *m - 1;
for (j = 1; j <= i__1; ++j) {
i__ = 0;
tmp1 = w[j];
i__2 = *m;
for (jj = j + 1; jj <= i__2; ++jj) {
if (w[jj] < tmp1) {
i__ = jj;
tmp1 = w[jj];
}
/* L40: */
}
if (i__ != 0) {
itmp1 = iwork[indibl + i__ - 1];
w[i__] = w[j];
iwork[indibl + i__ - 1] = iwork[indibl + j - 1];
w[j] = tmp1;
iwork[indibl + j - 1] = itmp1;
zswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[j * z_dim1 + 1],
&c__1);
if (*info != 0) {
itmp1 = ifail[i__];
ifail[i__] = ifail[j];
ifail[j] = itmp1;
}
}
/* L50: */
}
}
return 0;
/* End of ZHBGVX */
} /* zhbgvx_ */