cgees.c

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/* cgees.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 cgees_(char *jobvs, char *sort, L_fp select, integer *n, 
        complex *a, integer *lda, integer *sdim, complex *w, complex *vs, 
        integer *ldvs, complex *work, integer *lwork, real *rwork, logical *
        bwork, integer *info)
{
    /* System generated locals */
    integer a_dim1, a_offset, vs_dim1, vs_offset, i__1, i__2;

    /* Builtin functions */
    double sqrt(doublereal);

    /* Local variables */
    integer i__;
    real s;
    integer ihi, ilo;
    real dum[1], eps, sep;
    integer ibal;
    real anrm;
    integer ierr, itau, iwrk, icond, ieval;
    extern logical lsame_(char *, char *);
    extern /* Subroutine */ int ccopy_(integer *, complex *, integer *, 
            complex *, integer *), cgebak_(char *, char *, integer *, integer 
            *, integer *, real *, integer *, complex *, integer *, integer *), cgebal_(char *, integer *, complex *, integer *, 
            integer *, integer *, real *, integer *), slabad_(real *, 
            real *);
    logical scalea;
    extern doublereal clange_(char *, integer *, integer *, complex *, 
            integer *, real *);
    real cscale;
    extern /* Subroutine */ int cgehrd_(integer *, integer *, integer *, 
            complex *, integer *, complex *, complex *, integer *, integer *),
             clascl_(char *, integer *, integer *, real *, real *, integer *, 
            integer *, complex *, integer *, integer *);
    extern doublereal slamch_(char *);
    extern /* Subroutine */ int clacpy_(char *, integer *, integer *, complex 
            *, integer *, complex *, integer *), xerbla_(char *, 
            integer *);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
            integer *, integer *);
    real bignum;
    extern /* Subroutine */ int chseqr_(char *, char *, integer *, integer *, 
            integer *, complex *, integer *, complex *, complex *, integer *, 
            complex *, integer *, integer *), cunghr_(integer 
            *, integer *, integer *, complex *, integer *, complex *, complex 
            *, integer *, integer *), ctrsen_(char *, char *, logical *, 
            integer *, complex *, integer *, complex *, integer *, complex *, 
            integer *, real *, real *, complex *, integer *, integer *);
    integer minwrk, maxwrk;
    real smlnum;
    integer hswork;
    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 */
/*  ======= */

/*  CGEES computes for an N-by-N complex nonsymmetric matrix A, the */
/*  eigenvalues, the Schur form T, and, optionally, the matrix of Schur */
/*  vectors Z.  This gives the Schur factorization A = Z*T*(Z**H). */

/*  Optionally, it also orders the eigenvalues on the diagonal of the */
/*  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 complex matrix is in Schur form if it is upper triangular. */

/*  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 one COMPLEX argument */
/*          SELECT must be declared EXTERNAL in the calling subroutine. */
/*          If SORT = 'S', SELECT is used to select eigenvalues to order */
/*          to the top left of the Schur form. */
/*          IF SORT = 'N', SELECT is not referenced. */
/*          The eigenvalue W(j) is selected if SELECT(W(j)) is true. */

/*  N       (input) INTEGER */
/*          The order of the matrix A. N >= 0. */

/*  A       (input/output) COMPLEX array, dimension (LDA,N) */
/*          On entry, the N-by-N matrix A. */
/*          On exit, A has been overwritten by its 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 for which */
/*                         SELECT is true. */

/*  W       (output) COMPLEX array, dimension (N) */
/*          W contains the computed eigenvalues, in the same order that */
/*          they appear on the diagonal of the output Schur form T. */

/*  VS      (output) COMPLEX array, dimension (LDVS,N) */
/*          If JOBVS = 'V', VS contains the unitary 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) COMPLEX array, dimension (MAX(1,LWORK)) */
/*          On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */

/*  LWORK   (input) INTEGER */
/*          The dimension of the array WORK.  LWORK >= max(1,2*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. */

/*  RWORK   (workspace) REAL array, dimension (N) */

/*  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 W */
/*                      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;
    --w;
    vs_dim1 = *ldvs;
    vs_offset = 1 + vs_dim1;
    vs -= vs_offset;
    --work;
    --rwork;
    --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 = -10;
    }

/*     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. */
/*       CWorkspace refers to complex workspace, and RWorkspace to real */
/*       workspace. NB refers to the optimal block size for the */
/*       immediately following subroutine, as returned by ILAENV. */
/*       HSWORK refers to the workspace preferred by CHSEQR, 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 + *n * ilaenv_(&c__1, "CGEHRD", " ", n, &c__1, n, &
                    c__0);
            minwrk = *n << 1;

            chseqr_("S", jobvs, n, &c__1, n, &a[a_offset], lda, &w[1], &vs[
                    vs_offset], ldvs, &work[1], &c_n1, &ieval);
            hswork = work[1].r;

            if (! wantvs) {
                maxwrk = max(maxwrk,hswork);
            } else {
/* Computing MAX */
                i__1 = maxwrk, i__2 = *n + (*n - 1) * ilaenv_(&c__1, "CUNGHR", 
                         " ", n, &c__1, n, &c_n1);
                maxwrk = max(i__1,i__2);
                maxwrk = max(maxwrk,hswork);
            }
        }
        work[1].r = (real) maxwrk, work[1].i = 0.f;

        if (*lwork < minwrk && ! lquery) {
            *info = -12;
        }
    }

    if (*info != 0) {
        i__1 = -(*info);
        xerbla_("CGEES ", &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 = clange_("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) {
        clascl_("G", &c__0, &c__0, &anrm, &cscale, n, n, &a[a_offset], lda, &
                ierr);
    }

/*     Permute the matrix to make it more nearly triangular */
/*     (CWorkspace: none) */
/*     (RWorkspace: need N) */

    ibal = 1;
    cgebal_("P", n, &a[a_offset], lda, &ilo, &ihi, &rwork[ibal], &ierr);

/*     Reduce to upper Hessenberg form */
/*     (CWorkspace: need 2*N, prefer N+N*NB) */
/*     (RWorkspace: none) */

    itau = 1;
    iwrk = *n + itau;
    i__1 = *lwork - iwrk + 1;
    cgehrd_(n, &ilo, &ihi, &a[a_offset], lda, &work[itau], &work[iwrk], &i__1, 
             &ierr);

    if (wantvs) {

/*        Copy Householder vectors to VS */

        clacpy_("L", n, n, &a[a_offset], lda, &vs[vs_offset], ldvs)
                ;

/*        Generate unitary matrix in VS */
/*        (CWorkspace: need 2*N-1, prefer N+(N-1)*NB) */
/*        (RWorkspace: none) */

        i__1 = *lwork - iwrk + 1;
        cunghr_(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 */
/*     (CWorkspace: need 1, prefer HSWORK (see comments) ) */
/*     (RWorkspace: none) */

    iwrk = itau;
    i__1 = *lwork - iwrk + 1;
    chseqr_("S", jobvs, n, &ilo, &ihi, &a[a_offset], lda, &w[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) {
            clascl_("G", &c__0, &c__0, &cscale, &anrm, n, &c__1, &w[1], n, &
                    ierr);
        }
        i__1 = *n;
        for (i__ = 1; i__ <= i__1; ++i__) {
            bwork[i__] = (*select)(&w[i__]);
/* L10: */
        }

/*        Reorder eigenvalues and transform Schur vectors */
/*        (CWorkspace: none) */
/*        (RWorkspace: none) */

        i__1 = *lwork - iwrk + 1;
        ctrsen_("N", jobvs, &bwork[1], n, &a[a_offset], lda, &vs[vs_offset], 
                ldvs, &w[1], sdim, &s, &sep, &work[iwrk], &i__1, &icond);
    }

    if (wantvs) {

/*        Undo balancing */
/*        (CWorkspace: none) */
/*        (RWorkspace: need N) */

        cgebak_("P", "R", n, &ilo, &ihi, &rwork[ibal], n, &vs[vs_offset], 
                ldvs, &ierr);
    }

    if (scalea) {

/*        Undo scaling for the Schur form of A */

        clascl_("U", &c__0, &c__0, &cscale, &anrm, n, n, &a[a_offset], lda, &
                ierr);
        i__1 = *lda + 1;
        ccopy_(n, &a[a_offset], &i__1, &w[1], &c__1);
    }

    work[1].r = (real) maxwrk, work[1].i = 0.f;
    return 0;

/*     End of CGEES */

} /* cgees_ */