/* sgees.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static integer c__1 = 1;
static integer c__0 = 0;
static integer c_n1 = -1;
/* Subroutine */ int sgees_(char *jobvs, char *sort, L_fp select, integer *n,
real *a, integer *lda, integer *sdim, real *wr, real *wi, real *vs,
integer *ldvs, real *work, integer *lwork, logical *bwork, integer *
info)
{
/* System generated locals */
integer a_dim1, a_offset, vs_dim1, vs_offset, i__1, i__2, i__3;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__;
real s;
integer i1, i2, ip, ihi, ilo;
real dum[1], eps, sep;
integer ibal;
real anrm;
integer idum[1], ierr, itau, iwrk, inxt, icond, ieval;
extern logical lsame_(char *, char *);
logical cursl;
extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *,
integer *), sswap_(integer *, real *, integer *, real *, integer *
);
logical lst2sl;
extern /* Subroutine */ int slabad_(real *, real *);
logical scalea;
real cscale;
extern /* Subroutine */ int sgebak_(char *, char *, integer *, integer *,
integer *, real *, integer *, real *, integer *, integer *), sgebal_(char *, integer *, real *, integer *,
integer *, integer *, real *, integer *);
extern doublereal slamch_(char *), slange_(char *, integer *,
integer *, real *, integer *, real *);
extern /* Subroutine */ int sgehrd_(integer *, integer *, integer *, real
*, integer *, real *, real *, integer *, integer *), xerbla_(char
*, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
real bignum;
extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *,
real *, integer *, integer *, real *, integer *, integer *), slacpy_(char *, integer *, integer *, real *, integer *,
real *, integer *);
logical lastsl;
extern /* Subroutine */ int sorghr_(integer *, integer *, integer *, real
*, integer *, real *, real *, integer *, integer *), shseqr_(char
*, char *, integer *, integer *, integer *, real *, integer *,
real *, real *, real *, integer *, real *, integer *, integer *);
integer minwrk, maxwrk;
real smlnum;
integer hswork;
extern /* Subroutine */ int strsen_(char *, char *, logical *, integer *,
real *, integer *, real *, integer *, real *, real *, integer *,
real *, real *, real *, integer *, integer *, integer *, integer *
);
logical wantst, lquery, wantvs;
/* -- LAPACK driver routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* .. Function Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* SGEES computes for an N-by-N real nonsymmetric matrix A, the */
/* eigenvalues, the real Schur form T, and, optionally, the matrix of */
/* Schur vectors Z. This gives the Schur factorization A = Z*T*(Z**T). */
/* Optionally, it also orders the eigenvalues on the diagonal of the */
/* real Schur form so that selected eigenvalues are at the top left. */
/* The leading columns of Z then form an orthonormal basis for the */
/* invariant subspace corresponding to the selected eigenvalues. */
/* A matrix is in real Schur form if it is upper quasi-triangular with */
/* 1-by-1 and 2-by-2 blocks. 2-by-2 blocks will be standardized in the */
/* form */
/* [ a b ] */
/* [ c a ] */
/* where b*c < 0. The eigenvalues of such a block are a +- sqrt(bc). */
/* Arguments */
/* ========= */
/* JOBVS (input) CHARACTER*1 */
/* = 'N': Schur vectors are not computed; */
/* = 'V': Schur vectors are computed. */
/* SORT (input) CHARACTER*1 */
/* Specifies whether or not to order the eigenvalues on the */
/* diagonal of the Schur form. */
/* = 'N': Eigenvalues are not ordered; */
/* = 'S': Eigenvalues are ordered (see SELECT). */
/* SELECT (external procedure) LOGICAL FUNCTION of two REAL arguments */
/* SELECT must be declared EXTERNAL in the calling subroutine. */
/* If SORT = 'S', SELECT is used to select eigenvalues to sort */
/* to the top left of the Schur form. */
/* If SORT = 'N', SELECT is not referenced. */
/* An eigenvalue WR(j)+sqrt(-1)*WI(j) is selected if */
/* SELECT(WR(j),WI(j)) is true; i.e., if either one of a complex */
/* conjugate pair of eigenvalues is selected, then both complex */
/* eigenvalues are selected. */
/* Note that a selected complex eigenvalue may no longer */
/* satisfy SELECT(WR(j),WI(j)) = .TRUE. after ordering, since */
/* ordering may change the value of complex eigenvalues */
/* (especially if the eigenvalue is ill-conditioned); in this */
/* case INFO is set to N+2 (see INFO below). */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. */
/* A (input/output) REAL array, dimension (LDA,N) */
/* On entry, the N-by-N matrix A. */
/* On exit, A has been overwritten by its real Schur form T. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= max(1,N). */
/* SDIM (output) INTEGER */
/* If SORT = 'N', SDIM = 0. */
/* If SORT = 'S', SDIM = number of eigenvalues (after sorting) */
/* for which SELECT is true. (Complex conjugate */
/* pairs for which SELECT is true for either */
/* eigenvalue count as 2.) */
/* WR (output) REAL array, dimension (N) */
/* WI (output) REAL array, dimension (N) */
/* WR and WI contain the real and imaginary parts, */
/* respectively, of the computed eigenvalues in the same order */
/* that they appear on the diagonal of the output Schur form T. */
/* Complex conjugate pairs of eigenvalues will appear */
/* consecutively with the eigenvalue having the positive */
/* imaginary part first. */
/* VS (output) REAL array, dimension (LDVS,N) */
/* If JOBVS = 'V', VS contains the orthogonal matrix Z of Schur */
/* vectors. */
/* If JOBVS = 'N', VS is not referenced. */
/* LDVS (input) INTEGER */
/* The leading dimension of the array VS. LDVS >= 1; if */
/* JOBVS = 'V', LDVS >= N. */
/* WORK (workspace/output) REAL array, dimension (MAX(1,LWORK)) */
/* On exit, if INFO = 0, WORK(1) contains the optimal LWORK. */
/* LWORK (input) INTEGER */
/* The dimension of the array WORK. LWORK >= max(1,3*N). */
/* For good performance, LWORK must generally be larger. */
/* If LWORK = -1, then a workspace query is assumed; the routine */
/* only calculates the optimal size of the WORK array, returns */
/* this value as the first entry of the WORK array, and no error */
/* message related to LWORK is issued by XERBLA. */
/* BWORK (workspace) LOGICAL array, dimension (N) */
/* Not referenced if SORT = '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 QR algorithm failed to compute all the */
/* eigenvalues; elements 1:ILO-1 and i+1:N of WR and WI */
/* contain those eigenvalues which have converged; if */
/* JOBVS = 'V', VS contains the matrix which reduces A */
/* to its partially converged Schur form. */
/* = N+1: the eigenvalues could not be reordered because some */
/* eigenvalues were too close to separate (the problem */
/* is very ill-conditioned); */
/* = N+2: after reordering, roundoff changed values of some */
/* complex eigenvalues so that leading eigenvalues in */
/* the Schur form no longer satisfy SELECT=.TRUE. This */
/* could also be caused by underflow due to scaling. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Local Arrays .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input arguments */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--wr;
--wi;
vs_dim1 = *ldvs;
vs_offset = 1 + vs_dim1;
vs -= vs_offset;
--work;
--bwork;
/* Function Body */
*info = 0;
lquery = *lwork == -1;
wantvs = lsame_(jobvs, "V");
wantst = lsame_(sort, "S");
if (! wantvs && ! lsame_(jobvs, "N")) {
*info = -1;
} else if (! wantst && ! lsame_(sort, "N")) {
*info = -2;
} else if (*n < 0) {
*info = -4;
} else if (*lda < max(1,*n)) {
*info = -6;
} else if (*ldvs < 1 || wantvs && *ldvs < *n) {
*info = -11;
}
/* Compute workspace */
/* (Note: Comments in the code beginning "Workspace:" describe the */
/* minimal amount of workspace needed at that point in the code, */
/* as well as the preferred amount for good performance. */
/* NB refers to the optimal block size for the immediately */
/* following subroutine, as returned by ILAENV. */
/* HSWORK refers to the workspace preferred by SHSEQR, as */
/* calculated below. HSWORK is computed assuming ILO=1 and IHI=N, */
/* the worst case.) */
if (*info == 0) {
if (*n == 0) {
minwrk = 1;
maxwrk = 1;
} else {
maxwrk = (*n << 1) + *n * ilaenv_(&c__1, "SGEHRD", " ", n, &c__1,
n, &c__0);
minwrk = *n * 3;
shseqr_("S", jobvs, n, &c__1, n, &a[a_offset], lda, &wr[1], &wi[1]
, &vs[vs_offset], ldvs, &work[1], &c_n1, &ieval);
hswork = work[1];
if (! wantvs) {
/* Computing MAX */
i__1 = maxwrk, i__2 = *n + hswork;
maxwrk = max(i__1,i__2);
} else {
/* Computing MAX */
i__1 = maxwrk, i__2 = (*n << 1) + (*n - 1) * ilaenv_(&c__1,
"SORGHR", " ", n, &c__1, n, &c_n1);
maxwrk = max(i__1,i__2);
/* Computing MAX */
i__1 = maxwrk, i__2 = *n + hswork;
maxwrk = max(i__1,i__2);
}
}
work[1] = (real) maxwrk;
if (*lwork < minwrk && ! lquery) {
*info = -13;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("SGEES ", &i__1);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible */
if (*n == 0) {
*sdim = 0;
return 0;
}
/* Get machine constants */
eps = slamch_("P");
smlnum = slamch_("S");
bignum = 1.f / smlnum;
slabad_(&smlnum, &bignum);
smlnum = sqrt(smlnum) / eps;
bignum = 1.f / smlnum;
/* Scale A if max element outside range [SMLNUM,BIGNUM] */
anrm = slange_("M", n, n, &a[a_offset], lda, dum);
scalea = FALSE_;
if (anrm > 0.f && anrm < smlnum) {
scalea = TRUE_;
cscale = smlnum;
} else if (anrm > bignum) {
scalea = TRUE_;
cscale = bignum;
}
if (scalea) {
slascl_("G", &c__0, &c__0, &anrm, &cscale, n, n, &a[a_offset], lda, &
ierr);
}
/* Permute the matrix to make it more nearly triangular */
/* (Workspace: need N) */
ibal = 1;
sgebal_("P", n, &a[a_offset], lda, &ilo, &ihi, &work[ibal], &ierr);
/* Reduce to upper Hessenberg form */
/* (Workspace: need 3*N, prefer 2*N+N*NB) */
itau = *n + ibal;
iwrk = *n + itau;
i__1 = *lwork - iwrk + 1;
sgehrd_(n, &ilo, &ihi, &a[a_offset], lda, &work[itau], &work[iwrk], &i__1,
&ierr);
if (wantvs) {
/* Copy Householder vectors to VS */
slacpy_("L", n, n, &a[a_offset], lda, &vs[vs_offset], ldvs)
;
/* Generate orthogonal matrix in VS */
/* (Workspace: need 3*N-1, prefer 2*N+(N-1)*NB) */
i__1 = *lwork - iwrk + 1;
sorghr_(n, &ilo, &ihi, &vs[vs_offset], ldvs, &work[itau], &work[iwrk],
&i__1, &ierr);
}
*sdim = 0;
/* Perform QR iteration, accumulating Schur vectors in VS if desired */
/* (Workspace: need N+1, prefer N+HSWORK (see comments) ) */
iwrk = itau;
i__1 = *lwork - iwrk + 1;
shseqr_("S", jobvs, n, &ilo, &ihi, &a[a_offset], lda, &wr[1], &wi[1], &vs[
vs_offset], ldvs, &work[iwrk], &i__1, &ieval);
if (ieval > 0) {
*info = ieval;
}
/* Sort eigenvalues if desired */
if (wantst && *info == 0) {
if (scalea) {
slascl_("G", &c__0, &c__0, &cscale, &anrm, n, &c__1, &wr[1], n, &
ierr);
slascl_("G", &c__0, &c__0, &cscale, &anrm, n, &c__1, &wi[1], n, &
ierr);
}
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
bwork[i__] = (*select)(&wr[i__], &wi[i__]);
/* L10: */
}
/* Reorder eigenvalues and transform Schur vectors */
/* (Workspace: none needed) */
i__1 = *lwork - iwrk + 1;
strsen_("N", jobvs, &bwork[1], n, &a[a_offset], lda, &vs[vs_offset],
ldvs, &wr[1], &wi[1], sdim, &s, &sep, &work[iwrk], &i__1,
idum, &c__1, &icond);
if (icond > 0) {
*info = *n + icond;
}
}
if (wantvs) {
/* Undo balancing */
/* (Workspace: need N) */
sgebak_("P", "R", n, &ilo, &ihi, &work[ibal], n, &vs[vs_offset], ldvs,
&ierr);
}
if (scalea) {
/* Undo scaling for the Schur form of A */
slascl_("H", &c__0, &c__0, &cscale, &anrm, n, n, &a[a_offset], lda, &
ierr);
i__1 = *lda + 1;
scopy_(n, &a[a_offset], &i__1, &wr[1], &c__1);
if (cscale == smlnum) {
/* If scaling back towards underflow, adjust WI if an */
/* offdiagonal element of a 2-by-2 block in the Schur form */
/* underflows. */
if (ieval > 0) {
i1 = ieval + 1;
i2 = ihi - 1;
i__1 = ilo - 1;
/* Computing MAX */
i__3 = ilo - 1;
i__2 = max(i__3,1);
slascl_("G", &c__0, &c__0, &cscale, &anrm, &i__1, &c__1, &wi[
1], &i__2, &ierr);
} else if (wantst) {
i1 = 1;
i2 = *n - 1;
} else {
i1 = ilo;
i2 = ihi - 1;
}
inxt = i1 - 1;
i__1 = i2;
for (i__ = i1; i__ <= i__1; ++i__) {
if (i__ < inxt) {
goto L20;
}
if (wi[i__] == 0.f) {
inxt = i__ + 1;
} else {
if (a[i__ + 1 + i__ * a_dim1] == 0.f) {
wi[i__] = 0.f;
wi[i__ + 1] = 0.f;
} else if (a[i__ + 1 + i__ * a_dim1] != 0.f && a[i__ + (
i__ + 1) * a_dim1] == 0.f) {
wi[i__] = 0.f;
wi[i__ + 1] = 0.f;
if (i__ > 1) {
i__2 = i__ - 1;
sswap_(&i__2, &a[i__ * a_dim1 + 1], &c__1, &a[(
i__ + 1) * a_dim1 + 1], &c__1);
}
if (*n > i__ + 1) {
i__2 = *n - i__ - 1;
sswap_(&i__2, &a[i__ + (i__ + 2) * a_dim1], lda, &
a[i__ + 1 + (i__ + 2) * a_dim1], lda);
}
if (wantvs) {
sswap_(n, &vs[i__ * vs_dim1 + 1], &c__1, &vs[(i__
+ 1) * vs_dim1 + 1], &c__1);
}
a[i__ + (i__ + 1) * a_dim1] = a[i__ + 1 + i__ *
a_dim1];
a[i__ + 1 + i__ * a_dim1] = 0.f;
}
inxt = i__ + 2;
}
L20:
;
}
}
/* Undo scaling for the imaginary part of the eigenvalues */
i__1 = *n - ieval;
/* Computing MAX */
i__3 = *n - ieval;
i__2 = max(i__3,1);
slascl_("G", &c__0, &c__0, &cscale, &anrm, &i__1, &c__1, &wi[ieval +
1], &i__2, &ierr);
}
if (wantst && *info == 0) {
/* Check if reordering successful */
lastsl = TRUE_;
lst2sl = TRUE_;
*sdim = 0;
ip = 0;
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
cursl = (*select)(&wr[i__], &wi[i__]);
if (wi[i__] == 0.f) {
if (cursl) {
++(*sdim);
}
ip = 0;
if (cursl && ! lastsl) {
*info = *n + 2;
}
} else {
if (ip == 1) {
/* Last eigenvalue of conjugate pair */
cursl = cursl || lastsl;
lastsl = cursl;
if (cursl) {
*sdim += 2;
}
ip = -1;
if (cursl && ! lst2sl) {
*info = *n + 2;
}
} else {
/* First eigenvalue of conjugate pair */
ip = 1;
}
}
lst2sl = lastsl;
lastsl = cursl;
/* L30: */
}
}
work[1] = (real) maxwrk;
return 0;
/* End of SGEES */
} /* sgees_ */