/* slaed0.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static integer c__9 = 9;
static integer c__0 = 0;
static integer c__2 = 2;
static real c_b23 = 1.f;
static real c_b24 = 0.f;
static integer c__1 = 1;
/* Subroutine */ int slaed0_(integer *icompq, integer *qsiz, integer *n, real
*d__, real *e, real *q, integer *ldq, real *qstore, integer *ldqs,
real *work, integer *iwork, integer *info)
{
/* System generated locals */
integer q_dim1, q_offset, qstore_dim1, qstore_offset, i__1, i__2;
real r__1;
/* Builtin functions */
double log(doublereal);
integer pow_ii(integer *, integer *);
/* Local variables */
integer i__, j, k, iq, lgn, msd2, smm1, spm1, spm2;
real temp;
integer curr;
extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *,
integer *, real *, real *, integer *, real *, integer *, real *,
real *, integer *);
integer iperm, indxq, iwrem;
extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *,
integer *);
integer iqptr, tlvls;
extern /* Subroutine */ int slaed1_(integer *, real *, real *, integer *,
integer *, real *, integer *, real *, integer *, integer *),
slaed7_(integer *, integer *, integer *, integer *, integer *,
integer *, real *, real *, integer *, integer *, real *, integer *
, real *, integer *, integer *, integer *, integer *, integer *,
real *, real *, integer *, integer *);
integer igivcl;
extern /* Subroutine */ int xerbla_(char *, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
integer igivnm, submat;
extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *,
integer *, real *, integer *);
integer curprb, subpbs, igivpt, curlvl, matsiz, iprmpt, smlsiz;
extern /* Subroutine */ int ssteqr_(char *, integer *, real *, real *,
real *, integer *, real *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SLAED0 computes all eigenvalues and corresponding eigenvectors of a */
/* symmetric tridiagonal matrix using the divide and conquer method. */
/* Arguments */
/* ========= */
/* ICOMPQ (input) INTEGER */
/* = 0: Compute eigenvalues only. */
/* = 1: Compute eigenvectors of original dense symmetric matrix */
/* also. On entry, Q contains the orthogonal matrix used */
/* to reduce the original matrix to tridiagonal form. */
/* = 2: Compute eigenvalues and eigenvectors of tridiagonal */
/* matrix. */
/* QSIZ (input) INTEGER */
/* The dimension of the orthogonal matrix used to reduce */
/* the full matrix to tridiagonal form. QSIZ >= N if ICOMPQ = 1. */
/* N (input) INTEGER */
/* The dimension of the symmetric tridiagonal matrix. N >= 0. */
/* D (input/output) REAL array, dimension (N) */
/* On entry, the main diagonal of the tridiagonal matrix. */
/* On exit, its eigenvalues. */
/* E (input) REAL array, dimension (N-1) */
/* The off-diagonal elements of the tridiagonal matrix. */
/* On exit, E has been destroyed. */
/* Q (input/output) REAL array, dimension (LDQ, N) */
/* On entry, Q must contain an N-by-N orthogonal matrix. */
/* If ICOMPQ = 0 Q is not referenced. */
/* If ICOMPQ = 1 On entry, Q is a subset of the columns of the */
/* orthogonal matrix used to reduce the full */
/* matrix to tridiagonal form corresponding to */
/* the subset of the full matrix which is being */
/* decomposed at this time. */
/* If ICOMPQ = 2 On entry, Q will be the identity matrix. */
/* On exit, Q contains the eigenvectors of the */
/* tridiagonal matrix. */
/* LDQ (input) INTEGER */
/* The leading dimension of the array Q. If eigenvectors are */
/* desired, then LDQ >= max(1,N). In any case, LDQ >= 1. */
/* QSTORE (workspace) REAL array, dimension (LDQS, N) */
/* Referenced only when ICOMPQ = 1. Used to store parts of */
/* the eigenvector matrix when the updating matrix multiplies */
/* take place. */
/* LDQS (input) INTEGER */
/* The leading dimension of the array QSTORE. If ICOMPQ = 1, */
/* then LDQS >= max(1,N). In any case, LDQS >= 1. */
/* WORK (workspace) REAL array, */
/* If ICOMPQ = 0 or 1, the dimension of WORK must be at least */
/* 1 + 3*N + 2*N*lg N + 2*N**2 */
/* ( lg( N ) = smallest integer k */
/* such that 2^k >= N ) */
/* If ICOMPQ = 2, the dimension of WORK must be at least */
/* 4*N + N**2. */
/* IWORK (workspace) INTEGER array, */
/* If ICOMPQ = 0 or 1, the dimension of IWORK must be at least */
/* 6 + 6*N + 5*N*lg N. */
/* ( lg( N ) = smallest integer k */
/* such that 2^k >= N ) */
/* If ICOMPQ = 2, the dimension of IWORK must be at least */
/* 3 + 5*N. */
/* INFO (output) INTEGER */
/* = 0: successful exit. */
/* < 0: if INFO = -i, the i-th argument had an illegal value. */
/* > 0: The algorithm failed to compute an eigenvalue while */
/* working on the submatrix lying in rows and columns */
/* INFO/(N+1) through mod(INFO,N+1). */
/* Further Details */
/* =============== */
/* Based on contributions by */
/* Jeff Rutter, Computer Science Division, University of California */
/* at Berkeley, USA */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
--d__;
--e;
q_dim1 = *ldq;
q_offset = 1 + q_dim1;
q -= q_offset;
qstore_dim1 = *ldqs;
qstore_offset = 1 + qstore_dim1;
qstore -= qstore_offset;
--work;
--iwork;
/* Function Body */
*info = 0;
if (*icompq < 0 || *icompq > 2) {
*info = -1;
} else if (*icompq == 1 && *qsiz < max(0,*n)) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*ldq < max(1,*n)) {
*info = -7;
} else if (*ldqs < max(1,*n)) {
*info = -9;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SLAED0", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
smlsiz = ilaenv_(&c__9, "SLAED0", " ", &c__0, &c__0, &c__0, &c__0);
/* Determine the size and placement of the submatrices, and save in */
/* the leading elements of IWORK. */
iwork[1] = *n;
subpbs = 1;
tlvls = 0;
L10:
if (iwork[subpbs] > smlsiz) {
for (j = subpbs; j >= 1; --j) {
iwork[j * 2] = (iwork[j] + 1) / 2;
iwork[(j << 1) - 1] = iwork[j] / 2;
/* L20: */
}
++tlvls;
subpbs <<= 1;
goto L10;
}
i__1 = subpbs;
for (j = 2; j <= i__1; ++j) {
iwork[j] += iwork[j - 1];
/* L30: */
}
/* Divide the matrix into SUBPBS submatrices of size at most SMLSIZ+1 */
/* using rank-1 modifications (cuts). */
spm1 = subpbs - 1;
i__1 = spm1;
for (i__ = 1; i__ <= i__1; ++i__) {
submat = iwork[i__] + 1;
smm1 = submat - 1;
d__[smm1] -= (r__1 = e[smm1], dabs(r__1));
d__[submat] -= (r__1 = e[smm1], dabs(r__1));
/* L40: */
}
indxq = (*n << 2) + 3;
if (*icompq != 2) {
/* Set up workspaces for eigenvalues only/accumulate new vectors */
/* routine */
temp = log((real) (*n)) / log(2.f);
lgn = (integer) temp;
if (pow_ii(&c__2, &lgn) < *n) {
++lgn;
}
if (pow_ii(&c__2, &lgn) < *n) {
++lgn;
}
iprmpt = indxq + *n + 1;
iperm = iprmpt + *n * lgn;
iqptr = iperm + *n * lgn;
igivpt = iqptr + *n + 2;
igivcl = igivpt + *n * lgn;
igivnm = 1;
iq = igivnm + (*n << 1) * lgn;
/* Computing 2nd power */
i__1 = *n;
iwrem = iq + i__1 * i__1 + 1;
/* Initialize pointers */
i__1 = subpbs;
for (i__ = 0; i__ <= i__1; ++i__) {
iwork[iprmpt + i__] = 1;
iwork[igivpt + i__] = 1;
/* L50: */
}
iwork[iqptr] = 1;
}
/* Solve each submatrix eigenproblem at the bottom of the divide and */
/* conquer tree. */
curr = 0;
i__1 = spm1;
for (i__ = 0; i__ <= i__1; ++i__) {
if (i__ == 0) {
submat = 1;
matsiz = iwork[1];
} else {
submat = iwork[i__] + 1;
matsiz = iwork[i__ + 1] - iwork[i__];
}
if (*icompq == 2) {
ssteqr_("I", &matsiz, &d__[submat], &e[submat], &q[submat +
submat * q_dim1], ldq, &work[1], info);
if (*info != 0) {
goto L130;
}
} else {
ssteqr_("I", &matsiz, &d__[submat], &e[submat], &work[iq - 1 +
iwork[iqptr + curr]], &matsiz, &work[1], info);
if (*info != 0) {
goto L130;
}
if (*icompq == 1) {
sgemm_("N", "N", qsiz, &matsiz, &matsiz, &c_b23, &q[submat *
q_dim1 + 1], ldq, &work[iq - 1 + iwork[iqptr + curr]],
&matsiz, &c_b24, &qstore[submat * qstore_dim1 + 1],
ldqs);
}
/* Computing 2nd power */
i__2 = matsiz;
iwork[iqptr + curr + 1] = iwork[iqptr + curr] + i__2 * i__2;
++curr;
}
k = 1;
i__2 = iwork[i__ + 1];
for (j = submat; j <= i__2; ++j) {
iwork[indxq + j] = k;
++k;
/* L60: */
}
/* L70: */
}
/* Successively merge eigensystems of adjacent submatrices */
/* into eigensystem for the corresponding larger matrix. */
/* while ( SUBPBS > 1 ) */
curlvl = 1;
L80:
if (subpbs > 1) {
spm2 = subpbs - 2;
i__1 = spm2;
for (i__ = 0; i__ <= i__1; i__ += 2) {
if (i__ == 0) {
submat = 1;
matsiz = iwork[2];
msd2 = iwork[1];
curprb = 0;
} else {
submat = iwork[i__] + 1;
matsiz = iwork[i__ + 2] - iwork[i__];
msd2 = matsiz / 2;
++curprb;
}
/* Merge lower order eigensystems (of size MSD2 and MATSIZ - MSD2) */
/* into an eigensystem of size MATSIZ. */
/* SLAED1 is used only for the full eigensystem of a tridiagonal */
/* matrix. */
/* SLAED7 handles the cases in which eigenvalues only or eigenvalues */
/* and eigenvectors of a full symmetric matrix (which was reduced to */
/* tridiagonal form) are desired. */
if (*icompq == 2) {
slaed1_(&matsiz, &d__[submat], &q[submat + submat * q_dim1],
ldq, &iwork[indxq + submat], &e[submat + msd2 - 1], &
msd2, &work[1], &iwork[subpbs + 1], info);
} else {
slaed7_(icompq, &matsiz, qsiz, &tlvls, &curlvl, &curprb, &d__[
submat], &qstore[submat * qstore_dim1 + 1], ldqs, &
iwork[indxq + submat], &e[submat + msd2 - 1], &msd2, &
work[iq], &iwork[iqptr], &iwork[iprmpt], &iwork[iperm]
, &iwork[igivpt], &iwork[igivcl], &work[igivnm], &
work[iwrem], &iwork[subpbs + 1], info);
}
if (*info != 0) {
goto L130;
}
iwork[i__ / 2 + 1] = iwork[i__ + 2];
/* L90: */
}
subpbs /= 2;
++curlvl;
goto L80;
}
/* end while */
/* Re-merge the eigenvalues/vectors which were deflated at the final */
/* merge step. */
if (*icompq == 1) {
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
j = iwork[indxq + i__];
work[i__] = d__[j];
scopy_(qsiz, &qstore[j * qstore_dim1 + 1], &c__1, &q[i__ * q_dim1
+ 1], &c__1);
/* L100: */
}
scopy_(n, &work[1], &c__1, &d__[1], &c__1);
} else if (*icompq == 2) {
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
j = iwork[indxq + i__];
work[i__] = d__[j];
scopy_(n, &q[j * q_dim1 + 1], &c__1, &work[*n * i__ + 1], &c__1);
/* L110: */
}
scopy_(n, &work[1], &c__1, &d__[1], &c__1);
slacpy_("A", n, n, &work[*n + 1], n, &q[q_offset], ldq);
} else {
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
j = iwork[indxq + i__];
work[i__] = d__[j];
/* L120: */
}
scopy_(n, &work[1], &c__1, &d__[1], &c__1);
}
goto L140;
L130:
*info = submat * (*n + 1) + submat + matsiz - 1;
L140:
return 0;
/* End of SLAED0 */
} /* slaed0_ */