/* Subroutine */ int ssbgv_(char *jobz, char *uplo, integer *n, integer *ka,
integer *kb, real *ab, integer *ldab, real *bb, integer *ldbb, real *
w, real *z__, integer *ldz, real *work, integer *info)
{
/* -- LAPACK driver routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
September 30, 1994
Purpose
=======
SSBGV computes all the eigenvalues, and optionally, the eigenvectors
of a real generalized symmetric-definite banded eigenproblem, of
the form A*x=(lambda)*B*x. Here A and B are assumed to be symmetric
and banded, and B is also positive definite.
Arguments
=========
JOBZ (input) CHARACTER*1
= 'N': Compute eigenvalues only;
= 'V': Compute eigenvalues and eigenvectors.
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) REAL array, dimension (LDAB, N)
On entry, the upper or lower triangle of the symmetric 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) REAL array, dimension (LDBB, N)
On entry, the upper or lower triangle of the symmetric 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**T*S, as returned by SPBSTF.
LDBB (input) INTEGER
The leading dimension of the array BB. LDBB >= KB+1.
W (output) REAL array, dimension (N)
If INFO = 0, the eigenvalues in ascending order.
Z (output) REAL 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**T*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) REAL array, dimension (3*N)
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: the algorithm failed to converge:
i off-diagonal elements of an intermediate
tridiagonal form did not converge to zero;
> N: if INFO = N + i, for 1 <= i <= N, then SPBSTF
returned INFO = i: B is not positive definite.
The factorization of B could not be completed and
no eigenvalues or eigenvectors were computed.
=====================================================================
Test the input parameters.
Parameter adjustments */
/* System generated locals */
integer ab_dim1, ab_offset, bb_dim1, bb_offset, z_dim1, z_offset, i__1;
/* Local variables */
static integer inde;
static char vect[1];
extern logical lsame_(char *, char *);
static integer iinfo;
static logical upper, wantz;
extern /* Subroutine */ int xerbla_(char *, integer *);
static integer indwrk;
extern /* Subroutine */ int spbstf_(char *, integer *, integer *, real *,
integer *, integer *), ssbtrd_(char *, char *, integer *,
integer *, real *, integer *, real *, real *, real *, integer *,
real *, integer *), ssbgst_(char *, char *,
integer *, integer *, integer *, real *, integer *, real *,
integer *, real *, integer *, real *, integer *),
ssterf_(integer *, real *, real *, integer *), ssteqr_(char *,
integer *, real *, real *, real *, integer *, real *, integer *);
ab_dim1 = *ldab;
ab_offset = 1 + ab_dim1 * 1;
ab -= ab_offset;
bb_dim1 = *ldbb;
bb_offset = 1 + bb_dim1 * 1;
bb -= bb_offset;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1 * 1;
z__ -= z_offset;
--work;
/* Function Body */
wantz = lsame_(jobz, "V");
upper = lsame_(uplo, "U");
*info = 0;
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (upper || lsame_(uplo, "L"))) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*ka < 0) {
*info = -4;
} else if (*kb < 0 || *kb > *ka) {
*info = -5;
} else if (*ldab < *ka + 1) {
*info = -7;
} else if (*ldbb < *kb + 1) {
*info = -9;
} else if (*ldz < 1 || wantz && *ldz < *n) {
*info = -12;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SSBGV ", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Form a split Cholesky factorization of B. */
spbstf_(uplo, n, kb, &bb[bb_offset], ldbb, info);
if (*info != 0) {
*info = *n + *info;
return 0;
}
/* Transform problem to standard eigenvalue problem. */
inde = 1;
indwrk = inde + *n;
ssbgst_(jobz, uplo, n, ka, kb, &ab[ab_offset], ldab, &bb[bb_offset], ldbb,
&z__[z_offset], ldz, &work[indwrk], &iinfo)
;
/* Reduce to tridiagonal form. */
if (wantz) {
*(unsigned char *)vect = 'U';
} else {
*(unsigned char *)vect = 'N';
}
ssbtrd_(vect, uplo, n, ka, &ab[ab_offset], ldab, &w[1], &work[inde], &z__[
z_offset], ldz, &work[indwrk], &iinfo);
/* For eigenvalues only, call SSTERF. For eigenvectors, call SSTEQR. */
if (! wantz) {
ssterf_(n, &w[1], &work[inde], info);
} else {
ssteqr_(jobz, n, &w[1], &work[inde], &z__[z_offset], ldz, &work[
indwrk], info);
}
return 0;
/* End of SSBGV */
} /* ssbgv_ */
/* Subroutine */ int ssbevx_(char *jobz, char *range, char *uplo, integer *n,
integer *kd, real *ab, integer *ldab, real *q, integer *ldq, real *vl,
real *vu, integer *il, integer *iu, real *abstol, integer *m, real *
w, real *z__, integer *ldz, real *work, integer *iwork, integer *
ifail, integer *info)
{
/* System generated locals */
integer ab_dim1, ab_offset, q_dim1, q_offset, z_dim1, z_offset, i__1,
i__2;
real r__1, r__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__, j, jj;
real eps, vll, vuu, tmp1;
integer indd, inde;
real anrm;
integer imax;
real rmin, rmax;
logical test;
integer itmp1, indee;
real sigma;
extern logical lsame_(char *, char *);
integer iinfo;
extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *);
char order[1];
extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *,
real *, integer *, real *, integer *, real *, real *, integer *);
logical lower;
extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *,
integer *), sswap_(integer *, real *, integer *, real *, integer *
);
logical wantz, alleig, indeig;
integer iscale, indibl;
logical valeig;
extern doublereal slamch_(char *);
real safmin;
extern /* Subroutine */ int xerbla_(char *, integer *);
real abstll, bignum;
extern doublereal slansb_(char *, char *, integer *, integer *, real *,
integer *, real *);
extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *,
real *, integer *, integer *, real *, integer *, integer *);
integer indisp, indiwo;
extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *,
integer *, real *, integer *);
integer indwrk;
extern /* Subroutine */ int ssbtrd_(char *, char *, integer *, integer *,
real *, integer *, real *, real *, real *, integer *, real *,
integer *), sstein_(integer *, real *, real *,
integer *, real *, integer *, integer *, real *, integer *, real *
, integer *, integer *, integer *), ssterf_(integer *, real *,
real *, integer *);
integer nsplit;
real smlnum;
extern /* Subroutine */ int sstebz_(char *, char *, integer *, real *,
real *, integer *, integer *, real *, real *, real *, integer *,
integer *, real *, integer *, integer *, real *, integer *,
integer *), ssteqr_(char *, integer *, real *,
real *, real *, integer *, real *, integer *);
/* -- LAPACK driver routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SSBEVX computes selected eigenvalues and, optionally, eigenvectors */
/* of a real symmetric band 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. */
/* KD (input) INTEGER */
/* The number of superdiagonals of the matrix A if UPLO = 'U', */
/* or the number of subdiagonals if UPLO = 'L'. KD >= 0. */
/* AB (input/output) REAL array, dimension (LDAB, N) */
/* On entry, the upper or lower triangle of the symmetric band */
/* matrix A, stored in the first KD+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(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; */
/* if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd). */
/* On exit, AB is overwritten by values generated during the */
/* reduction to tridiagonal form. If UPLO = 'U', the first */
/* superdiagonal and the diagonal of the tridiagonal matrix T */
/* are returned in rows KD and KD+1 of AB, and if UPLO = 'L', */
/* the diagonal and first subdiagonal of T are returned in the */
/* first two rows of AB. */
/* LDAB (input) INTEGER */
/* The leading dimension of the array AB. LDAB >= KD + 1. */
/* Q (output) REAL array, dimension (LDQ, N) */
/* If JOBZ = 'V', the N-by-N orthogonal matrix used in the */
/* reduction to tridiagonal form. */
/* If JOBZ = 'N', the array Q is not referenced. */
/* LDQ (input) INTEGER */
/* The leading dimension of the array Q. If JOBZ = 'V', then */
/* LDQ >= max(1,N). */
/* VL (input) REAL */
/* VU (input) REAL */
/* 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) REAL */
/* 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 AB to tridiagonal form. */
/* Eigenvalues will be computed most accurately when ABSTOL is */
/* set to twice the underflow threshold 2*SLAMCH('S'), not zero. */
/* If this routine returns with INFO>0, indicating that some */
/* eigenvectors did not converge, try setting ABSTOL to */
/* 2*SLAMCH('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) REAL array, dimension (N) */
/* The first M elements contain the selected eigenvalues in */
/* ascending order. */
/* Z (output) REAL 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) REAL 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 */
ab_dim1 = *ldab;
ab_offset = 1 + ab_dim1;
ab -= ab_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;
--iwork;
--ifail;
/* Function Body */
wantz = lsame_(jobz, "V");
alleig = lsame_(range, "A");
valeig = lsame_(range, "V");
indeig = lsame_(range, "I");
lower = lsame_(uplo, "L");
*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 (*kd < 0) {
*info = -5;
} else if (*ldab < *kd + 1) {
*info = -7;
} else if (wantz && *ldq < max(1,*n)) {
*info = -9;
} else {
if (valeig) {
if (*n > 0 && *vu <= *vl) {
*info = -11;
}
} else if (indeig) {
if (*il < 1 || *il > max(1,*n)) {
*info = -12;
} else if (*iu < min(*n,*il) || *iu > *n) {
*info = -13;
}
}
}
if (*info == 0) {
if (*ldz < 1 || wantz && *ldz < *n) {
*info = -18;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SSBEVX", &i__1);
return 0;
}
/* Quick return if possible */
*m = 0;
if (*n == 0) {
return 0;
}
if (*n == 1) {
*m = 1;
if (lower) {
tmp1 = ab[ab_dim1 + 1];
} else {
tmp1 = ab[*kd + 1 + ab_dim1];
}
if (valeig) {
if (! (*vl < tmp1 && *vu >= tmp1)) {
*m = 0;
}
}
if (*m == 1) {
w[1] = tmp1;
if (wantz) {
z__[z_dim1 + 1] = 1.f;
}
}
return 0;
}
/* Get machine constants. */
safmin = slamch_("Safe minimum");
eps = slamch_("Precision");
smlnum = safmin / eps;
bignum = 1.f / smlnum;
rmin = sqrt(smlnum);
/* Computing MIN */
r__1 = sqrt(bignum), r__2 = 1.f / sqrt(sqrt(safmin));
rmax = dmin(r__1,r__2);
/* Scale matrix to allowable range, if necessary. */
iscale = 0;
abstll = *abstol;
if (valeig) {
vll = *vl;
vuu = *vu;
} else {
vll = 0.f;
vuu = 0.f;
}
anrm = slansb_("M", uplo, n, kd, &ab[ab_offset], ldab, &work[1]);
if (anrm > 0.f && anrm < rmin) {
iscale = 1;
sigma = rmin / anrm;
} else if (anrm > rmax) {
iscale = 1;
sigma = rmax / anrm;
}
if (iscale == 1) {
if (lower) {
slascl_("B", kd, kd, &c_b14, &sigma, n, n, &ab[ab_offset], ldab,
info);
} else {
slascl_("Q", kd, kd, &c_b14, &sigma, n, n, &ab[ab_offset], ldab,
info);
}
if (*abstol > 0.f) {
abstll = *abstol * sigma;
}
if (valeig) {
vll = *vl * sigma;
vuu = *vu * sigma;
}
}
/* Call SSBTRD to reduce symmetric band matrix to tridiagonal form. */
indd = 1;
inde = indd + *n;
indwrk = inde + *n;
ssbtrd_(jobz, uplo, n, kd, &ab[ab_offset], ldab, &work[indd], &work[inde],
&q[q_offset], ldq, &work[indwrk], &iinfo);
/* If all eigenvalues are desired and ABSTOL is less than or equal */
/* to zero, then call SSTERF or SSTEQR. If this fails for some */
/* eigenvalue, then try SSTEBZ. */
test = FALSE_;
if (indeig) {
if (*il == 1 && *iu == *n) {
test = TRUE_;
}
}
if ((alleig || test) && *abstol <= 0.f) {
scopy_(n, &work[indd], &c__1, &w[1], &c__1);
indee = indwrk + (*n << 1);
if (! wantz) {
i__1 = *n - 1;
scopy_(&i__1, &work[inde], &c__1, &work[indee], &c__1);
ssterf_(n, &w[1], &work[indee], info);
} else {
slacpy_("A", n, n, &q[q_offset], ldq, &z__[z_offset], ldz);
i__1 = *n - 1;
scopy_(&i__1, &work[inde], &c__1, &work[indee], &c__1);
ssteqr_(jobz, n, &w[1], &work[indee], &z__[z_offset], ldz, &work[
indwrk], 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 SSTEBZ and, if eigenvectors are desired, SSTEIN. */
if (wantz) {
*(unsigned char *)order = 'B';
} else {
*(unsigned char *)order = 'E';
}
indibl = 1;
indisp = indibl + *n;
indiwo = indisp + *n;
sstebz_(range, order, n, &vll, &vuu, il, iu, &abstll, &work[indd], &work[
inde], m, &nsplit, &w[1], &iwork[indibl], &iwork[indisp], &work[
indwrk], &iwork[indiwo], info);
if (wantz) {
sstein_(n, &work[indd], &work[inde], m, &w[1], &iwork[indibl], &iwork[
indisp], &z__[z_offset], ldz, &work[indwrk], &iwork[indiwo], &
ifail[1], info);
/* Apply orthogonal matrix used in reduction to tridiagonal */
/* form to eigenvectors returned by SSTEIN. */
i__1 = *m;
for (j = 1; j <= i__1; ++j) {
scopy_(n, &z__[j * z_dim1 + 1], &c__1, &work[1], &c__1);
sgemv_("N", n, n, &c_b14, &q[q_offset], ldq, &work[1], &c__1, &
c_b34, &z__[j * z_dim1 + 1], &c__1);
/* L20: */
}
}
/* If matrix was scaled, then rescale eigenvalues appropriately. */
L30:
if (iscale == 1) {
if (*info == 0) {
imax = *m;
} else {
imax = *info - 1;
}
r__1 = 1.f / sigma;
sscal_(&imax, &r__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];
}
/* 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;
sswap_(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 SSBEVX */
} /* ssbevx_ */
int ssbgv_(char *jobz, char *uplo, int *n, int *ka,
int *kb, float *ab, int *ldab, float *bb, int *ldbb, float *
w, float *z__, int *ldz, float *work, int *info)
{
/* System generated locals */
int ab_dim1, ab_offset, bb_dim1, bb_offset, z_dim1, z_offset, i__1;
/* Local variables */
int inde;
char vect[1];
extern int lsame_(char *, char *);
int iinfo;
int upper, wantz;
extern int xerbla_(char *, int *);
int indwrk;
extern int spbstf_(char *, int *, int *, float *,
int *, int *), ssbtrd_(char *, char *, int *,
int *, float *, int *, float *, float *, float *, int *,
float *, int *), ssbgst_(char *, char *,
int *, int *, int *, float *, int *, float *,
int *, float *, int *, float *, int *),
ssterf_(int *, float *, float *, int *), ssteqr_(char *,
int *, float *, float *, float *, int *, float *, int *);
/* -- LAPACK driver routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SSBGV computes all the eigenvalues, and optionally, the eigenvectors */
/* of a float generalized symmetric-definite banded eigenproblem, of */
/* the form A*x=(lambda)*B*x. Here A and B are assumed to be symmetric */
/* and banded, and B is also positive definite. */
/* Arguments */
/* ========= */
/* JOBZ (input) CHARACTER*1 */
/* = 'N': Compute eigenvalues only; */
/* = 'V': Compute eigenvalues and eigenvectors. */
/* 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) REAL array, dimension (LDAB, N) */
/* On entry, the upper or lower triangle of the symmetric 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) REAL array, dimension (LDBB, N) */
/* On entry, the upper or lower triangle of the symmetric 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**T*S, as returned by SPBSTF. */
/* LDBB (input) INTEGER */
/* The leading dimension of the array BB. LDBB >= KB+1. */
/* W (output) REAL array, dimension (N) */
/* If INFO = 0, the eigenvalues in ascending order. */
/* Z (output) REAL 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**T*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) REAL array, dimension (3*N) */
/* 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: the algorithm failed to converge: */
/* i off-diagonal elements of an intermediate */
/* tridiagonal form did not converge to zero; */
/* > N: if INFO = N + i, for 1 <= i <= N, then SPBSTF */
/* returned INFO = i: B is not positive definite. */
/* The factorization of B could not be completed and */
/* no eigenvalues or eigenvectors were computed. */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. 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;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
/* Function Body */
wantz = lsame_(jobz, "V");
upper = lsame_(uplo, "U");
*info = 0;
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (upper || lsame_(uplo, "L"))) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*ka < 0) {
*info = -4;
} else if (*kb < 0 || *kb > *ka) {
*info = -5;
} else if (*ldab < *ka + 1) {
*info = -7;
} else if (*ldbb < *kb + 1) {
*info = -9;
} else if (*ldz < 1 || wantz && *ldz < *n) {
*info = -12;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SSBGV ", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Form a split Cholesky factorization of B. */
spbstf_(uplo, n, kb, &bb[bb_offset], ldbb, info);
if (*info != 0) {
*info = *n + *info;
return 0;
}
/* Transform problem to standard eigenvalue problem. */
inde = 1;
indwrk = inde + *n;
ssbgst_(jobz, uplo, n, ka, kb, &ab[ab_offset], ldab, &bb[bb_offset], ldbb,
&z__[z_offset], ldz, &work[indwrk], &iinfo)
;
/* Reduce to tridiagonal form. */
if (wantz) {
*(unsigned char *)vect = 'U';
} else {
*(unsigned char *)vect = 'N';
}
ssbtrd_(vect, uplo, n, ka, &ab[ab_offset], ldab, &w[1], &work[inde], &z__[
z_offset], ldz, &work[indwrk], &iinfo);
/* For eigenvalues only, call SSTERF. For eigenvectors, call SSTEQR. */
if (! wantz) {
ssterf_(n, &w[1], &work[inde], info);
} else {
ssteqr_(jobz, n, &w[1], &work[inde], &z__[z_offset], ldz, &work[
indwrk], info);
}
return 0;
/* End of SSBGV */
} /* ssbgv_ */
int ssbev_(char *jobz, char *uplo, int *n, int *kd,
float *ab, int *ldab, float *w, float *z__, int *ldz, float *work,
int *info)
{
/* System generated locals */
int ab_dim1, ab_offset, z_dim1, z_offset, i__1;
float r__1;
/* Builtin functions */
double sqrt(double);
/* Local variables */
float eps;
int inde;
float anrm;
int imax;
float rmin, rmax, sigma;
extern int lsame_(char *, char *);
int iinfo;
extern int sscal_(int *, float *, float *, int *);
int lower, wantz;
int iscale;
extern double slamch_(char *);
float safmin;
extern int xerbla_(char *, int *);
float bignum;
extern double slansb_(char *, char *, int *, int *, float *,
int *, float *);
extern int slascl_(char *, int *, int *, float *,
float *, int *, int *, float *, int *, int *);
int indwrk;
extern int ssbtrd_(char *, char *, int *, int *,
float *, int *, float *, float *, float *, int *, float *,
int *), ssterf_(int *, float *, float *,
int *);
float smlnum;
extern int ssteqr_(char *, int *, float *, float *,
float *, int *, float *, int *);
/* -- LAPACK driver routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SSBEV computes all the eigenvalues and, optionally, eigenvectors of */
/* a float symmetric band matrix A. */
/* Arguments */
/* ========= */
/* JOBZ (input) CHARACTER*1 */
/* = 'N': Compute eigenvalues only; */
/* = 'V': Compute eigenvalues and eigenvectors. */
/* 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. */
/* KD (input) INTEGER */
/* The number of superdiagonals of the matrix A if UPLO = 'U', */
/* or the number of subdiagonals if UPLO = 'L'. KD >= 0. */
/* AB (input/output) REAL array, dimension (LDAB, N) */
/* On entry, the upper or lower triangle of the symmetric band */
/* matrix A, stored in the first KD+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(kd+1+i-j,j) = A(i,j) for MAX(1,j-kd)<=i<=j; */
/* if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=MIN(n,j+kd). */
/* On exit, AB is overwritten by values generated during the */
/* reduction to tridiagonal form. If UPLO = 'U', the first */
/* superdiagonal and the diagonal of the tridiagonal matrix T */
/* are returned in rows KD and KD+1 of AB, and if UPLO = 'L', */
/* the diagonal and first subdiagonal of T are returned in the */
/* first two rows of AB. */
/* LDAB (input) INTEGER */
/* The leading dimension of the array AB. LDAB >= KD + 1. */
/* W (output) REAL array, dimension (N) */
/* If INFO = 0, the eigenvalues in ascending order. */
/* Z (output) REAL array, dimension (LDZ, N) */
/* If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal */
/* eigenvectors of the matrix A, with the i-th column of Z */
/* holding the eigenvector associated with W(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 >= MAX(1,N). */
/* WORK (workspace) REAL array, dimension (MAX(1,3*N-2)) */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* > 0: if INFO = i, the algorithm failed to converge; i */
/* off-diagonal elements of an intermediate tridiagonal */
/* form did not converge to zero. */
/* ===================================================================== */
/* .. 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;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
/* Function Body */
wantz = lsame_(jobz, "V");
lower = lsame_(uplo, "L");
*info = 0;
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (lower || lsame_(uplo, "U"))) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*kd < 0) {
*info = -4;
} else if (*ldab < *kd + 1) {
*info = -6;
} else if (*ldz < 1 || wantz && *ldz < *n) {
*info = -9;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SSBEV ", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (*n == 1) {
if (lower) {
w[1] = ab[ab_dim1 + 1];
} else {
w[1] = ab[*kd + 1 + ab_dim1];
}
if (wantz) {
z__[z_dim1 + 1] = 1.f;
}
return 0;
}
/* Get machine constants. */
safmin = slamch_("Safe minimum");
eps = slamch_("Precision");
smlnum = safmin / eps;
bignum = 1.f / smlnum;
rmin = sqrt(smlnum);
rmax = sqrt(bignum);
/* Scale matrix to allowable range, if necessary. */
anrm = slansb_("M", uplo, n, kd, &ab[ab_offset], ldab, &work[1]);
iscale = 0;
if (anrm > 0.f && anrm < rmin) {
iscale = 1;
sigma = rmin / anrm;
} else if (anrm > rmax) {
iscale = 1;
sigma = rmax / anrm;
}
if (iscale == 1) {
if (lower) {
slascl_("B", kd, kd, &c_b11, &sigma, n, n, &ab[ab_offset], ldab,
info);
} else {
slascl_("Q", kd, kd, &c_b11, &sigma, n, n, &ab[ab_offset], ldab,
info);
}
}
/* Call SSBTRD to reduce symmetric band matrix to tridiagonal form. */
inde = 1;
indwrk = inde + *n;
ssbtrd_(jobz, uplo, n, kd, &ab[ab_offset], ldab, &w[1], &work[inde], &z__[
z_offset], ldz, &work[indwrk], &iinfo);
/* For eigenvalues only, call SSTERF. For eigenvectors, call SSTEQR. */
if (! wantz) {
ssterf_(n, &w[1], &work[inde], info);
} else {
ssteqr_(jobz, n, &w[1], &work[inde], &z__[z_offset], ldz, &work[
indwrk], info);
}
/* If matrix was scaled, then rescale eigenvalues appropriately. */
if (iscale == 1) {
if (*info == 0) {
imax = *n;
} else {
imax = *info - 1;
}
r__1 = 1.f / sigma;
sscal_(&imax, &r__1, &w[1], &c__1);
}
return 0;
/* End of SSBEV */
} /* ssbev_ */
int main(void)
{
/* Local scalars */
char vect, vect_i;
char uplo, uplo_i;
lapack_int n, n_i;
lapack_int kd, kd_i;
lapack_int ldab, ldab_i;
lapack_int ldab_r;
lapack_int ldq, ldq_i;
lapack_int ldq_r;
lapack_int info, info_i;
lapack_int i;
int failed;
/* Local arrays */
float *ab = NULL, *ab_i = NULL;
float *d = NULL, *d_i = NULL;
float *e = NULL, *e_i = NULL;
float *q = NULL, *q_i = NULL;
float *work = NULL, *work_i = NULL;
float *ab_save = NULL;
float *d_save = NULL;
float *e_save = NULL;
float *q_save = NULL;
float *ab_r = NULL;
float *q_r = NULL;
/* Iniitialize the scalar parameters */
init_scalars_ssbtrd( &vect, &uplo, &n, &kd, &ldab, &ldq );
ldab_r = n+2;
ldq_r = n+2;
vect_i = vect;
uplo_i = uplo;
n_i = n;
kd_i = kd;
ldab_i = ldab;
ldq_i = ldq;
/* Allocate memory for the LAPACK routine arrays */
ab = (float *)LAPACKE_malloc( ldab*n * sizeof(float) );
d = (float *)LAPACKE_malloc( n * sizeof(float) );
e = (float *)LAPACKE_malloc( (n-1) * sizeof(float) );
q = (float *)LAPACKE_malloc( ldq*n * sizeof(float) );
work = (float *)LAPACKE_malloc( n * sizeof(float) );
/* Allocate memory for the C interface function arrays */
ab_i = (float *)LAPACKE_malloc( ldab*n * sizeof(float) );
d_i = (float *)LAPACKE_malloc( n * sizeof(float) );
e_i = (float *)LAPACKE_malloc( (n-1) * sizeof(float) );
q_i = (float *)LAPACKE_malloc( ldq*n * sizeof(float) );
work_i = (float *)LAPACKE_malloc( n * sizeof(float) );
/* Allocate memory for the backup arrays */
ab_save = (float *)LAPACKE_malloc( ldab*n * sizeof(float) );
d_save = (float *)LAPACKE_malloc( n * sizeof(float) );
e_save = (float *)LAPACKE_malloc( (n-1) * sizeof(float) );
q_save = (float *)LAPACKE_malloc( ldq*n * sizeof(float) );
/* Allocate memory for the row-major arrays */
ab_r = (float *)LAPACKE_malloc( (kd+1)*(n+2) * sizeof(float) );
q_r = (float *)LAPACKE_malloc( n*(n+2) * sizeof(float) );
/* Initialize input arrays */
init_ab( ldab*n, ab );
init_d( n, d );
init_e( (n-1), e );
init_q( ldq*n, q );
init_work( n, work );
/* Backup the ouptut arrays */
for( i = 0; i < ldab*n; i++ ) {
ab_save[i] = ab[i];
}
for( i = 0; i < n; i++ ) {
d_save[i] = d[i];
}
for( i = 0; i < (n-1); i++ ) {
e_save[i] = e[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_save[i] = q[i];
}
/* Call the LAPACK routine */
ssbtrd_( &vect, &uplo, &n, &kd, ab, &ldab, d, e, q, &ldq, work, &info );
/* Initialize input data, call the column-major middle-level
* interface to LAPACK routine and check the results */
for( i = 0; i < ldab*n; i++ ) {
ab_i[i] = ab_save[i];
}
for( i = 0; i < n; i++ ) {
d_i[i] = d_save[i];
}
for( i = 0; i < (n-1); i++ ) {
e_i[i] = e_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
info_i = LAPACKE_ssbtrd_work( LAPACK_COL_MAJOR, vect_i, uplo_i, n_i, kd_i,
ab_i, ldab_i, d_i, e_i, q_i, ldq_i, work_i );
failed = compare_ssbtrd( ab, ab_i, d, d_i, e, e_i, q, q_i, info, info_i,
ldab, ldq, n, vect );
if( failed == 0 ) {
printf( "PASSED: column-major middle-level interface to ssbtrd\n" );
} else {
printf( "FAILED: column-major middle-level interface to ssbtrd\n" );
}
/* Initialize input data, call the column-major high-level
* interface to LAPACK routine and check the results */
for( i = 0; i < ldab*n; i++ ) {
ab_i[i] = ab_save[i];
}
for( i = 0; i < n; i++ ) {
d_i[i] = d_save[i];
}
for( i = 0; i < (n-1); i++ ) {
e_i[i] = e_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
info_i = LAPACKE_ssbtrd( LAPACK_COL_MAJOR, vect_i, uplo_i, n_i, kd_i, ab_i,
ldab_i, d_i, e_i, q_i, ldq_i );
failed = compare_ssbtrd( ab, ab_i, d, d_i, e, e_i, q, q_i, info, info_i,
ldab, ldq, n, vect );
if( failed == 0 ) {
printf( "PASSED: column-major high-level interface to ssbtrd\n" );
} else {
printf( "FAILED: column-major high-level interface to ssbtrd\n" );
}
/* Initialize input data, call the row-major middle-level
* interface to LAPACK routine and check the results */
for( i = 0; i < ldab*n; i++ ) {
ab_i[i] = ab_save[i];
}
for( i = 0; i < n; i++ ) {
d_i[i] = d_save[i];
}
for( i = 0; i < (n-1); i++ ) {
e_i[i] = e_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
LAPACKE_sge_trans( LAPACK_COL_MAJOR, kd+1, n, ab_i, ldab, ab_r, n+2 );
if( LAPACKE_lsame( vect, 'u' ) || LAPACKE_lsame( vect, 'v' ) ) {
LAPACKE_sge_trans( LAPACK_COL_MAJOR, n, n, q_i, ldq, q_r, n+2 );
}
info_i = LAPACKE_ssbtrd_work( LAPACK_ROW_MAJOR, vect_i, uplo_i, n_i, kd_i,
ab_r, ldab_r, d_i, e_i, q_r, ldq_r, work_i );
LAPACKE_sge_trans( LAPACK_ROW_MAJOR, kd+1, n, ab_r, n+2, ab_i, ldab );
if( LAPACKE_lsame( vect, 'u' ) || LAPACKE_lsame( vect, 'v' ) ) {
LAPACKE_sge_trans( LAPACK_ROW_MAJOR, n, n, q_r, n+2, q_i, ldq );
}
failed = compare_ssbtrd( ab, ab_i, d, d_i, e, e_i, q, q_i, info, info_i,
ldab, ldq, n, vect );
if( failed == 0 ) {
printf( "PASSED: row-major middle-level interface to ssbtrd\n" );
} else {
printf( "FAILED: row-major middle-level interface to ssbtrd\n" );
}
/* Initialize input data, call the row-major high-level
* interface to LAPACK routine and check the results */
for( i = 0; i < ldab*n; i++ ) {
ab_i[i] = ab_save[i];
}
for( i = 0; i < n; i++ ) {
d_i[i] = d_save[i];
}
for( i = 0; i < (n-1); i++ ) {
e_i[i] = e_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
/* Init row_major arrays */
LAPACKE_sge_trans( LAPACK_COL_MAJOR, kd+1, n, ab_i, ldab, ab_r, n+2 );
if( LAPACKE_lsame( vect, 'u' ) || LAPACKE_lsame( vect, 'v' ) ) {
LAPACKE_sge_trans( LAPACK_COL_MAJOR, n, n, q_i, ldq, q_r, n+2 );
}
info_i = LAPACKE_ssbtrd( LAPACK_ROW_MAJOR, vect_i, uplo_i, n_i, kd_i, ab_r,
ldab_r, d_i, e_i, q_r, ldq_r );
LAPACKE_sge_trans( LAPACK_ROW_MAJOR, kd+1, n, ab_r, n+2, ab_i, ldab );
if( LAPACKE_lsame( vect, 'u' ) || LAPACKE_lsame( vect, 'v' ) ) {
LAPACKE_sge_trans( LAPACK_ROW_MAJOR, n, n, q_r, n+2, q_i, ldq );
}
failed = compare_ssbtrd( ab, ab_i, d, d_i, e, e_i, q, q_i, info, info_i,
ldab, ldq, n, vect );
if( failed == 0 ) {
printf( "PASSED: row-major high-level interface to ssbtrd\n" );
} else {
printf( "FAILED: row-major high-level interface to ssbtrd\n" );
}
/* Release memory */
if( ab != NULL ) {
LAPACKE_free( ab );
}
if( ab_i != NULL ) {
LAPACKE_free( ab_i );
}
if( ab_r != NULL ) {
LAPACKE_free( ab_r );
}
if( ab_save != NULL ) {
LAPACKE_free( ab_save );
}
if( d != NULL ) {
LAPACKE_free( d );
}
if( d_i != NULL ) {
LAPACKE_free( d_i );
}
if( d_save != NULL ) {
LAPACKE_free( d_save );
}
if( e != NULL ) {
LAPACKE_free( e );
}
if( e_i != NULL ) {
LAPACKE_free( e_i );
}
if( e_save != NULL ) {
LAPACKE_free( e_save );
}
if( q != NULL ) {
LAPACKE_free( q );
}
if( q_i != NULL ) {
LAPACKE_free( q_i );
}
if( q_r != NULL ) {
LAPACKE_free( q_r );
}
if( q_save != NULL ) {
LAPACKE_free( q_save );
}
if( work != NULL ) {
LAPACKE_free( work );
}
if( work_i != NULL ) {
LAPACKE_free( work_i );
}
return 0;
}
/* Subroutine */ int ssbevx_(char *jobz, char *range, char *uplo, integer *n,
integer *kd, real *ab, integer *ldab, real *q, integer *ldq, real *vl,
real *vu, integer *il, integer *iu, real *abstol, integer *m, real *
w, real *z, integer *ldz, real *work, 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
=======
SSBEVX computes selected eigenvalues and, optionally, eigenvectors
of a real symmetric band 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.
KD (input) INTEGER
The number of superdiagonals of the matrix A if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KD >= 0.
AB (input/output) REAL array, dimension (LDAB, N)
On entry, the upper or lower triangle of the symmetric band
matrix A, stored in the first KD+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(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;
if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd).
On exit, AB is overwritten by values generated during the
reduction to tridiagonal form. If UPLO = 'U', the first
superdiagonal and the diagonal of the tridiagonal matrix T
are returned in rows KD and KD+1 of AB, and if UPLO = 'L',
the diagonal and first subdiagonal of T are returned in the
first two rows of AB.
LDAB (input) INTEGER
The leading dimension of the array AB. LDAB >= KD + 1.
Q (output) REAL array, dimension (LDQ, N)
If JOBZ = 'V', the N-by-N orthogonal matrix used in the
reduction to tridiagonal form.
If JOBZ = 'N', the array Q is not referenced.
LDQ (input) INTEGER
The leading dimension of the array Q. If JOBZ = 'V', then
LDQ >= max(1,N).
VL (input) REAL
VU (input) REAL
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) REAL
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 AB to tridiagonal form.
Eigenvalues will be computed most accurately when ABSTOL is
set to twice the underflow threshold 2*SLAMCH('S'), not zero.
If this routine returns with INFO>0, indicating that some
eigenvectors did not converge, try setting ABSTOL to
2*SLAMCH('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) REAL array, dimension (N)
The first M elements contain the selected eigenvalues in
ascending order.
Z (output) REAL 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) REAL 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 real c_b14 = 1.f;
static integer c__1 = 1;
static real c_b34 = 0.f;
/* System generated locals */
integer ab_dim1, ab_offset, q_dim1, q_offset, z_dim1, z_offset, i__1,
i__2;
real r__1, r__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
static integer indd, inde;
static real anrm;
static integer imax;
static real rmin, rmax;
static integer itmp1, i, j, indee;
static real sigma;
extern logical lsame_(char *, char *);
static integer iinfo;
extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *);
static char order[1];
extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *,
real *, integer *, real *, integer *, real *, real *, integer *);
static logical lower;
extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *,
integer *), sswap_(integer *, real *, integer *, real *, integer *
);
static logical wantz;
static integer jj;
static logical alleig, indeig;
static integer iscale, indibl;
static logical valeig;
extern doublereal slamch_(char *);
static real safmin;
extern /* Subroutine */ int xerbla_(char *, integer *);
static real abstll, bignum;
extern doublereal slansb_(char *, char *, integer *, integer *, real *,
integer *, real *);
extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *,
real *, integer *, integer *, real *, integer *, integer *);
static integer indisp, indiwo;
extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *,
integer *, real *, integer *);
static integer indwrk;
extern /* Subroutine */ int ssbtrd_(char *, char *, integer *, integer *,
real *, integer *, real *, real *, real *, integer *, real *,
integer *), sstein_(integer *, real *, real *,
integer *, real *, integer *, integer *, real *, integer *, real *
, integer *, integer *, integer *), ssterf_(integer *, real *,
real *, integer *);
static integer nsplit;
static real smlnum;
extern /* Subroutine */ int sstebz_(char *, char *, integer *, real *,
real *, integer *, integer *, real *, real *, real *, integer *,
integer *, real *, integer *, integer *, real *, integer *,
integer *), ssteqr_(char *, integer *, real *,
real *, real *, integer *, real *, integer *);
static real eps, vll, vuu, tmp1;
#define W(I) w[(I)-1]
#define WORK(I) work[(I)-1]
#define IWORK(I) iwork[(I)-1]
#define IFAIL(I) ifail[(I)-1]
#define AB(I,J) ab[(I)-1 + ((J)-1)* ( *ldab)]
#define Q(I,J) q[(I)-1 + ((J)-1)* ( *ldq)]
#define Z(I,J) z[(I)-1 + ((J)-1)* ( *ldz)]
wantz = lsame_(jobz, "V");
alleig = lsame_(range, "A");
valeig = lsame_(range, "V");
indeig = lsame_(range, "I");
lower = lsame_(uplo, "L");
*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 (*kd < 0) {
*info = -5;
} else if (*ldab < *kd + 1) {
*info = -7;
} else if (*ldq < *n) {
*info = -9;
} else if (valeig && *n > 0 && *vu <= *vl) {
*info = -11;
} else if (indeig && *il < 1) {
*info = -12;
} else if (indeig && (*iu < min(*n,*il) || *iu > *n)) {
*info = -13;
} else if (*ldz < 1 || wantz && *ldz < *n) {
*info = -18;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SSBEVX", &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) = AB(1,1);
} else {
if (*vl < AB(1,1) && *vu >= AB(1,1)) {
*m = 1;
W(1) = AB(1,1);
}
}
if (wantz) {
Z(1,1) = 1.f;
}
return 0;
}
/* Get machine constants. */
safmin = slamch_("Safe minimum");
eps = slamch_("Precision");
smlnum = safmin / eps;
bignum = 1.f / smlnum;
rmin = sqrt(smlnum);
/* Computing MIN */
r__1 = sqrt(bignum), r__2 = 1.f / sqrt(sqrt(safmin));
rmax = dmin(r__1,r__2);
/* Scale matrix to allowable range, if necessary. */
iscale = 0;
abstll = *abstol;
if (valeig) {
vll = *vl;
vuu = *vu;
}
anrm = slansb_("M", uplo, n, kd, &AB(1,1), ldab, &WORK(1));
if (anrm > 0.f && anrm < rmin) {
iscale = 1;
sigma = rmin / anrm;
} else if (anrm > rmax) {
iscale = 1;
sigma = rmax / anrm;
}
if (iscale == 1) {
if (lower) {
slascl_("B", kd, kd, &c_b14, &sigma, n, n, &AB(1,1), ldab,
info);
} else {
slascl_("Q", kd, kd, &c_b14, &sigma, n, n, &AB(1,1), ldab,
info);
}
if (*abstol > 0.f) {
abstll = *abstol * sigma;
}
if (valeig) {
vll = *vl * sigma;
vuu = *vu * sigma;
}
}
/* Call SSBTRD to reduce symmetric band matrix to tridiagonal form. */
indd = 1;
inde = indd + *n;
indwrk = inde + *n;
ssbtrd_(jobz, uplo, n, kd, &AB(1,1), ldab, &WORK(indd), &WORK(inde),
&Q(1,1), ldq, &WORK(indwrk), &iinfo);
/* If all eigenvalues are desired and ABSTOL is less than or equal
to zero, then call SSTERF or SSTEQR. If this fails for some
eigenvalue, then try SSTEBZ. */
if ((alleig || indeig && *il == 1 && *iu == *n) && *abstol <= 0.f) {
scopy_(n, &WORK(indd), &c__1, &W(1), &c__1);
indee = indwrk + (*n << 1);
if (! wantz) {
i__1 = *n - 1;
scopy_(&i__1, &WORK(inde), &c__1, &WORK(indee), &c__1);
ssterf_(n, &W(1), &WORK(indee), info);
} else {
slacpy_("A", n, n, &Q(1,1), ldq, &Z(1,1), ldz);
i__1 = *n - 1;
scopy_(&i__1, &WORK(inde), &c__1, &WORK(indee), &c__1);
ssteqr_(jobz, n, &W(1), &WORK(indee), &Z(1,1), ldz, &WORK(
indwrk), info);
if (*info == 0) {
i__1 = *n;
for (i = 1; i <= *n; ++i) {
IFAIL(i) = 0;
/* L10: */
}
}
}
if (*info == 0) {
*m = *n;
goto L30;
}
*info = 0;
}
/* Otherwise, call SSTEBZ and, if eigenvectors are desired, SSTEIN. */
if (wantz) {
*(unsigned char *)order = 'B';
} else {
*(unsigned char *)order = 'E';
}
indibl = 1;
indisp = indibl + *n;
indiwo = indisp + *n;
sstebz_(range, order, n, &vll, &vuu, il, iu, &abstll, &WORK(indd), &WORK(
inde), m, &nsplit, &W(1), &IWORK(indibl), &IWORK(indisp), &WORK(
indwrk), &IWORK(indiwo), info);
if (wantz) {
sstein_(n, &WORK(indd), &WORK(inde), m, &W(1), &IWORK(indibl), &IWORK(
indisp), &Z(1,1), ldz, &WORK(indwrk), &IWORK(indiwo), &
IFAIL(1), info);
/* Apply orthogonal matrix used in reduction to tridiagonal
form to eigenvectors returned by SSTEIN. */
i__1 = *m;
for (j = 1; j <= *m; ++j) {
scopy_(n, &Z(1,j), &c__1, &WORK(1), &c__1);
sgemv_("N", n, n, &c_b14, &Q(1,1), ldq, &WORK(1), &c__1, &
c_b34, &Z(1,j), &c__1);
/* L20: */
}
}
/* If matrix was scaled, then rescale eigenvalues appropriately. */
L30:
if (iscale == 1) {
if (*info == 0) {
imax = *m;
} else {
imax = *info - 1;
}
r__1 = 1.f / sigma;
sscal_(&imax, &r__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);
}
/* 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;
sswap_(n, &Z(1,i), &c__1, &Z(1,j), &
c__1);
if (*info != 0) {
itmp1 = IFAIL(i);
IFAIL(i) = IFAIL(j);
IFAIL(j) = itmp1;
}
}
/* L50: */
}
}
return 0;
/* End of SSBEVX */
} /* ssbevx_ */
int ssbgvd_(char *jobz, char *uplo, int *n, int *ka,
int *kb, float *ab, int *ldab, float *bb, int *ldbb, float *
w, float *z__, int *ldz, float *work, int *lwork, int *
iwork, int *liwork, int *info)
{
/* System generated locals */
int ab_dim1, ab_offset, bb_dim1, bb_offset, z_dim1, z_offset, i__1;
/* Local variables */
int inde;
char vect[1];
extern int lsame_(char *, char *);
int iinfo;
extern int sgemm_(char *, char *, int *, int *,
int *, float *, float *, int *, float *, int *, float *,
float *, int *);
int lwmin;
int upper, wantz;
int indwk2, llwrk2;
extern int xerbla_(char *, int *), sstedc_(
char *, int *, float *, float *, float *, int *, float *,
int *, int *, int *, int *), slacpy_(char
*, int *, int *, float *, int *, float *, int *);
int indwrk, liwmin;
extern int spbstf_(char *, int *, int *, float *,
int *, int *), ssbtrd_(char *, char *, int *,
int *, float *, int *, float *, float *, float *, int *,
float *, int *), ssbgst_(char *, char *,
int *, int *, int *, float *, int *, float *,
int *, float *, int *, float *, int *),
ssterf_(int *, float *, float *, int *);
int lquery;
/* -- LAPACK driver routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SSBGVD computes all the eigenvalues, and optionally, the eigenvectors */
/* of a float generalized symmetric-definite banded eigenproblem, of the */
/* form A*x=(lambda)*B*x. Here A and B are assumed to be symmetric and */
/* banded, and B is also positive definite. If eigenvectors are */
/* desired, it uses a divide and conquer algorithm. */
/* The divide and conquer algorithm makes very mild assumptions about */
/* floating point arithmetic. It will work on machines with a guard */
/* digit in add/subtract, or on those binary machines without guard */
/* digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or */
/* Cray-2. It could conceivably fail on hexadecimal or decimal machines */
/* without guard digits, but we know of none. */
/* Arguments */
/* ========= */
/* JOBZ (input) CHARACTER*1 */
/* = 'N': Compute eigenvalues only; */
/* = 'V': Compute eigenvalues and eigenvectors. */
/* 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) REAL array, dimension (LDAB, N) */
/* On entry, the upper or lower triangle of the symmetric 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) REAL array, dimension (LDBB, N) */
/* On entry, the upper or lower triangle of the symmetric 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(ka+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**T*S, as returned by SPBSTF. */
/* LDBB (input) INTEGER */
/* The leading dimension of the array BB. LDBB >= KB+1. */
/* W (output) REAL array, dimension (N) */
/* If INFO = 0, the eigenvalues in ascending order. */
/* Z (output) REAL 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 Z**T*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 >= MAX(1,N). */
/* WORK (workspace/output) REAL 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. */
/* If N <= 1, LWORK >= 1. */
/* If JOBZ = 'N' and N > 1, LWORK >= 3*N. */
/* If JOBZ = 'V' and N > 1, LWORK >= 1 + 5*N + 2*N**2. */
/* If LWORK = -1, then a workspace query is assumed; the routine */
/* only calculates the optimal sizes of the WORK and IWORK */
/* arrays, returns these values as the first entries of the WORK */
/* and IWORK arrays, and no error message related to LWORK or */
/* LIWORK is issued by XERBLA. */
/* IWORK (workspace/output) INTEGER array, dimension (MAX(1,LIWORK)) */
/* On exit, if LIWORK > 0, IWORK(1) returns the optimal LIWORK. */
/* LIWORK (input) INTEGER */
/* The dimension of the array IWORK. */
/* If JOBZ = 'N' or N <= 1, LIWORK >= 1. */
/* If JOBZ = 'V' and N > 1, LIWORK >= 3 + 5*N. */
/* If LIWORK = -1, then a workspace query is assumed; the */
/* routine only calculates the optimal sizes of the WORK and */
/* IWORK arrays, returns these values as the first entries of */
/* the WORK and IWORK arrays, and no error message related to */
/* LWORK or LIWORK is issued by XERBLA. */
/* 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: the algorithm failed to converge: */
/* i off-diagonal elements of an intermediate */
/* tridiagonal form did not converge to zero; */
/* > N: if INFO = N + i, for 1 <= i <= N, then SPBSTF */
/* 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 .. */
/* .. */
/* .. 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;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
--iwork;
/* Function Body */
wantz = lsame_(jobz, "V");
upper = lsame_(uplo, "U");
lquery = *lwork == -1 || *liwork == -1;
*info = 0;
if (*n <= 1) {
liwmin = 1;
lwmin = 1;
} else if (wantz) {
liwmin = *n * 5 + 3;
/* Computing 2nd power */
i__1 = *n;
lwmin = *n * 5 + 1 + (i__1 * i__1 << 1);
} else {
liwmin = 1;
lwmin = *n << 1;
}
if (! (wantz || lsame_(jobz, "N"))) {
*info = -1;
} else if (! (upper || lsame_(uplo, "L"))) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*ka < 0) {
*info = -4;
} else if (*kb < 0 || *kb > *ka) {
*info = -5;
} else if (*ldab < *ka + 1) {
*info = -7;
} else if (*ldbb < *kb + 1) {
*info = -9;
} else if (*ldz < 1 || wantz && *ldz < *n) {
*info = -12;
}
if (*info == 0) {
work[1] = (float) lwmin;
iwork[1] = liwmin;
if (*lwork < lwmin && ! lquery) {
*info = -14;
} else if (*liwork < liwmin && ! lquery) {
*info = -16;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SSBGVD", &i__1);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Form a split Cholesky factorization of B. */
spbstf_(uplo, n, kb, &bb[bb_offset], ldbb, info);
if (*info != 0) {
*info = *n + *info;
return 0;
}
/* Transform problem to standard eigenvalue problem. */
inde = 1;
indwrk = inde + *n;
indwk2 = indwrk + *n * *n;
llwrk2 = *lwork - indwk2 + 1;
ssbgst_(jobz, uplo, n, ka, kb, &ab[ab_offset], ldab, &bb[bb_offset], ldbb,
&z__[z_offset], ldz, &work[indwrk], &iinfo)
;
/* Reduce to tridiagonal form. */
if (wantz) {
*(unsigned char *)vect = 'U';
} else {
*(unsigned char *)vect = 'N';
}
ssbtrd_(vect, uplo, n, ka, &ab[ab_offset], ldab, &w[1], &work[inde], &z__[
z_offset], ldz, &work[indwrk], &iinfo);
/* For eigenvalues only, call SSTERF. For eigenvectors, call SSTEDC. */
if (! wantz) {
ssterf_(n, &w[1], &work[inde], info);
} else {
sstedc_("I", n, &w[1], &work[inde], &work[indwrk], n, &work[indwk2], &
llwrk2, &iwork[1], liwork, info);
sgemm_("N", "N", n, n, n, &c_b12, &z__[z_offset], ldz, &work[indwrk],
n, &c_b13, &work[indwk2], n);
slacpy_("A", n, n, &work[indwk2], n, &z__[z_offset], ldz);
}
work[1] = (float) lwmin;
iwork[1] = liwmin;
return 0;
/* End of SSBGVD */
} /* ssbgvd_ */