zgegv.c

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/* zgegv.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 doublecomplex c_b1 = {0.,0.};
static doublecomplex c_b2 = {1.,0.};
static integer c__1 = 1;
static integer c_n1 = -1;
static doublereal c_b29 = 1.;

/* Subroutine */ int zgegv_(char *jobvl, char *jobvr, integer *n, 
        doublecomplex *a, integer *lda, doublecomplex *b, integer *ldb, 
        doublecomplex *alpha, doublecomplex *beta, doublecomplex *vl, integer 
        *ldvl, doublecomplex *vr, integer *ldvr, doublecomplex *work, integer 
        *lwork, doublereal *rwork, integer *info)
{
    /* System generated locals */
    integer a_dim1, a_offset, b_dim1, b_offset, vl_dim1, vl_offset, vr_dim1, 
            vr_offset, i__1, i__2, i__3, i__4;
    doublereal d__1, d__2, d__3, d__4;
    doublecomplex z__1, z__2;

    /* Builtin functions */
    double d_imag(doublecomplex *);

    /* Local variables */
    integer jc, nb, in, jr, nb1, nb2, nb3, ihi, ilo;
    doublereal eps;
    logical ilv;
    doublereal absb, anrm, bnrm;
    integer itau;
    doublereal temp;
    logical ilvl, ilvr;
    integer lopt;
    doublereal anrm1, anrm2, bnrm1, bnrm2, absai, scale, absar, sbeta;
    extern logical lsame_(char *, char *);
    integer ileft, iinfo, icols, iwork, irows;
    extern doublereal dlamch_(char *);
    doublereal salfai;
    extern /* Subroutine */ int zggbak_(char *, char *, integer *, integer *, 
            integer *, doublereal *, doublereal *, integer *, doublecomplex *, 
             integer *, integer *), zggbal_(char *, integer *, 
             doublecomplex *, integer *, doublecomplex *, integer *, integer *
, integer *, doublereal *, doublereal *, doublereal *, integer *);
    doublereal salfar, safmin;
    extern /* Subroutine */ int xerbla_(char *, integer *);
    doublereal safmax;
    char chtemp[1];
    logical ldumma[1];
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
            integer *, integer *);
    extern doublereal zlange_(char *, integer *, integer *, doublecomplex *, 
            integer *, doublereal *);
    integer ijobvl, iright;
    logical ilimit;
    extern /* Subroutine */ int zgghrd_(char *, char *, integer *, integer *, 
            integer *, doublecomplex *, integer *, doublecomplex *, integer *, 
             doublecomplex *, integer *, doublecomplex *, integer *, integer *
), zlascl_(char *, integer *, integer *, 
            doublereal *, doublereal *, integer *, integer *, doublecomplex *, 
             integer *, integer *);
    integer ijobvr;
    extern /* Subroutine */ int zgeqrf_(integer *, integer *, doublecomplex *, 
             integer *, doublecomplex *, doublecomplex *, integer *, integer *
);
    integer lwkmin;
    extern /* Subroutine */ int zlacpy_(char *, integer *, integer *, 
            doublecomplex *, integer *, doublecomplex *, integer *), 
            zlaset_(char *, integer *, integer *, doublecomplex *, 
            doublecomplex *, doublecomplex *, integer *), ztgevc_(
            char *, char *, logical *, integer *, doublecomplex *, integer *, 
            doublecomplex *, integer *, doublecomplex *, integer *, 
            doublecomplex *, integer *, integer *, integer *, doublecomplex *, 
             doublereal *, integer *), zhgeqz_(char *, char *, 
             char *, integer *, integer *, integer *, doublecomplex *, 
            integer *, doublecomplex *, integer *, doublecomplex *, 
            doublecomplex *, doublecomplex *, integer *, doublecomplex *, 
            integer *, doublecomplex *, integer *, doublereal *, integer *);
    integer irwork, lwkopt;
    logical lquery;
    extern /* Subroutine */ int zungqr_(integer *, integer *, integer *, 
            doublecomplex *, integer *, doublecomplex *, doublecomplex *, 
            integer *, integer *), zunmqr_(char *, char *, integer *, integer 
            *, integer *, doublecomplex *, integer *, doublecomplex *, 
            doublecomplex *, integer *, doublecomplex *, integer *, integer *);


/*  -- LAPACK driver routine (version 3.2) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  This routine is deprecated and has been replaced by routine ZGGEV. */

/*  ZGEGV computes the eigenvalues and, optionally, the left and/or right */
/*  eigenvectors of a complex matrix pair (A,B). */
/*  Given two square matrices A and B, */
/*  the generalized nonsymmetric eigenvalue problem (GNEP) is to find the */
/*  eigenvalues lambda and corresponding (non-zero) eigenvectors x such */
/*  that */
/*     A*x = lambda*B*x. */

/*  An alternate form is to find the eigenvalues mu and corresponding */
/*  eigenvectors y such that */
/*     mu*A*y = B*y. */

/*  These two forms are equivalent with mu = 1/lambda and x = y if */
/*  neither lambda nor mu is zero.  In order to deal with the case that */
/*  lambda or mu is zero or small, two values alpha and beta are returned */
/*  for each eigenvalue, such that lambda = alpha/beta and */
/*  mu = beta/alpha. */

/*  The vectors x and y in the above equations are right eigenvectors of */
/*  the matrix pair (A,B).  Vectors u and v satisfying */
/*     u**H*A = lambda*u**H*B  or  mu*v**H*A = v**H*B */
/*  are left eigenvectors of (A,B). */

/*  Note: this routine performs "full balancing" on A and B -- see */
/*  "Further Details", below. */

/*  Arguments */
/*  ========= */

/*  JOBVL   (input) CHARACTER*1 */
/*          = 'N':  do not compute the left generalized eigenvectors; */
/*          = 'V':  compute the left generalized eigenvectors (returned */
/*                  in VL). */

/*  JOBVR   (input) CHARACTER*1 */
/*          = 'N':  do not compute the right generalized eigenvectors; */
/*          = 'V':  compute the right generalized eigenvectors (returned */
/*                  in VR). */

/*  N       (input) INTEGER */
/*          The order of the matrices A, B, VL, and VR.  N >= 0. */

/*  A       (input/output) COMPLEX*16 array, dimension (LDA, N) */
/*          On entry, the matrix A. */
/*          If JOBVL = 'V' or JOBVR = 'V', then on exit A */
/*          contains the Schur form of A from the generalized Schur */
/*          factorization of the pair (A,B) after balancing.  If no */
/*          eigenvectors were computed, then only the diagonal elements */
/*          of the Schur form will be correct.  See ZGGHRD and ZHGEQZ */
/*          for details. */

/*  LDA     (input) INTEGER */
/*          The leading dimension of A.  LDA >= max(1,N). */

/*  B       (input/output) COMPLEX*16 array, dimension (LDB, N) */
/*          On entry, the matrix B. */
/*          If JOBVL = 'V' or JOBVR = 'V', then on exit B contains the */
/*          upper triangular matrix obtained from B in the generalized */
/*          Schur factorization of the pair (A,B) after balancing. */
/*          If no eigenvectors were computed, then only the diagonal */
/*          elements of B will be correct.  See ZGGHRD and ZHGEQZ for */
/*          details. */

/*  LDB     (input) INTEGER */
/*          The leading dimension of B.  LDB >= max(1,N). */

/*  ALPHA   (output) COMPLEX*16 array, dimension (N) */
/*          The complex scalars alpha that define the eigenvalues of */
/*          GNEP. */

/*  BETA    (output) COMPLEX*16 array, dimension (N) */
/*          The complex scalars beta that define the eigenvalues of GNEP. */

/*          Together, the quantities alpha = ALPHA(j) and beta = BETA(j) */
/*          represent the j-th eigenvalue of the matrix pair (A,B), in */
/*          one of the forms lambda = alpha/beta or mu = beta/alpha. */
/*          Since either lambda or mu may overflow, they should not, */
/*          in general, be computed. */

/*  VL      (output) COMPLEX*16 array, dimension (LDVL,N) */
/*          If JOBVL = 'V', the left eigenvectors u(j) are stored */
/*          in the columns of VL, in the same order as their eigenvalues. */
/*          Each eigenvector is scaled so that its largest component has */
/*          abs(real part) + abs(imag. part) = 1, except for eigenvectors */
/*          corresponding to an eigenvalue with alpha = beta = 0, which */
/*          are set to zero. */
/*          Not referenced if JOBVL = 'N'. */

/*  LDVL    (input) INTEGER */
/*          The leading dimension of the matrix VL. LDVL >= 1, and */
/*          if JOBVL = 'V', LDVL >= N. */

/*  VR      (output) COMPLEX*16 array, dimension (LDVR,N) */
/*          If JOBVR = 'V', the right eigenvectors x(j) are stored */
/*          in the columns of VR, in the same order as their eigenvalues. */
/*          Each eigenvector is scaled so that its largest component has */
/*          abs(real part) + abs(imag. part) = 1, except for eigenvectors */
/*          corresponding to an eigenvalue with alpha = beta = 0, which */
/*          are set to zero. */
/*          Not referenced if JOBVR = 'N'. */

/*  LDVR    (input) INTEGER */
/*          The leading dimension of the matrix VR. LDVR >= 1, and */
/*          if JOBVR = 'V', LDVR >= N. */

/*  WORK    (workspace/output) COMPLEX*16 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. */
/*          To compute the optimal value of LWORK, call ILAENV to get */
/*          blocksizes (for ZGEQRF, ZUNMQR, and ZUNGQR.)  Then compute: */
/*          NB  -- MAX of the blocksizes for ZGEQRF, ZUNMQR, and ZUNGQR; */
/*          The optimal LWORK is  MAX( 2*N, N*(NB+1) ). */

/*          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/output) DOUBLE PRECISION array, dimension (8*N) */

/*  INFO    (output) INTEGER */
/*          = 0:  successful exit */
/*          < 0:  if INFO = -i, the i-th argument had an illegal value. */
/*          =1,...,N: */
/*                The QZ iteration failed.  No eigenvectors have been */
/*                calculated, but ALPHA(j) and BETA(j) should be */
/*                correct for j=INFO+1,...,N. */
/*          > N:  errors that usually indicate LAPACK problems: */
/*                =N+1: error return from ZGGBAL */
/*                =N+2: error return from ZGEQRF */
/*                =N+3: error return from ZUNMQR */
/*                =N+4: error return from ZUNGQR */
/*                =N+5: error return from ZGGHRD */
/*                =N+6: error return from ZHGEQZ (other than failed */
/*                                               iteration) */
/*                =N+7: error return from ZTGEVC */
/*                =N+8: error return from ZGGBAK (computing VL) */
/*                =N+9: error return from ZGGBAK (computing VR) */
/*                =N+10: error return from ZLASCL (various calls) */

/*  Further Details */
/*  =============== */

/*  Balancing */
/*  --------- */

/*  This driver calls ZGGBAL to both permute and scale rows and columns */
/*  of A and B.  The permutations PL and PR are chosen so that PL*A*PR */
/*  and PL*B*R will be upper triangular except for the diagonal blocks */
/*  A(i:j,i:j) and B(i:j,i:j), with i and j as close together as */
/*  possible.  The diagonal scaling matrices DL and DR are chosen so */
/*  that the pair  DL*PL*A*PR*DR, DL*PL*B*PR*DR have elements close to */
/*  one (except for the elements that start out zero.) */

/*  After the eigenvalues and eigenvectors of the balanced matrices */
/*  have been computed, ZGGBAK transforms the eigenvectors back to what */
/*  they would have been (in perfect arithmetic) if they had not been */
/*  balanced. */

/*  Contents of A and B on Exit */
/*  -------- -- - --- - -- ---- */

/*  If any eigenvectors are computed (either JOBVL='V' or JOBVR='V' or */
/*  both), then on exit the arrays A and B will contain the complex Schur */
/*  form[*] of the "balanced" versions of A and B.  If no eigenvectors */
/*  are computed, then only the diagonal blocks will be correct. */

/*  [*] In other words, upper triangular form. */

/*  ===================================================================== */

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. Local Arrays .. */
/*     .. */
/*     .. External Subroutines .. */
/*     .. */
/*     .. External Functions .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
/*     .. Statement Functions .. */
/*     .. */
/*     .. Statement Function definitions .. */
/*     .. */
/*     .. Executable Statements .. */

/*     Decode the input arguments */

    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    b_dim1 = *ldb;
    b_offset = 1 + b_dim1;
    b -= b_offset;
    --alpha;
    --beta;
    vl_dim1 = *ldvl;
    vl_offset = 1 + vl_dim1;
    vl -= vl_offset;
    vr_dim1 = *ldvr;
    vr_offset = 1 + vr_dim1;
    vr -= vr_offset;
    --work;
    --rwork;

    /* Function Body */
    if (lsame_(jobvl, "N")) {
        ijobvl = 1;
        ilvl = FALSE_;
    } else if (lsame_(jobvl, "V")) {
        ijobvl = 2;
        ilvl = TRUE_;
    } else {
        ijobvl = -1;
        ilvl = FALSE_;
    }

    if (lsame_(jobvr, "N")) {
        ijobvr = 1;
        ilvr = FALSE_;
    } else if (lsame_(jobvr, "V")) {
        ijobvr = 2;
        ilvr = TRUE_;
    } else {
        ijobvr = -1;
        ilvr = FALSE_;
    }
    ilv = ilvl || ilvr;

/*     Test the input arguments */

/* Computing MAX */
    i__1 = *n << 1;
    lwkmin = max(i__1,1);
    lwkopt = lwkmin;
    work[1].r = (doublereal) lwkopt, work[1].i = 0.;
    lquery = *lwork == -1;
    *info = 0;
    if (ijobvl <= 0) {
        *info = -1;
    } else if (ijobvr <= 0) {
        *info = -2;
    } else if (*n < 0) {
        *info = -3;
    } else if (*lda < max(1,*n)) {
        *info = -5;
    } else if (*ldb < max(1,*n)) {
        *info = -7;
    } else if (*ldvl < 1 || ilvl && *ldvl < *n) {
        *info = -11;
    } else if (*ldvr < 1 || ilvr && *ldvr < *n) {
        *info = -13;
    } else if (*lwork < lwkmin && ! lquery) {
        *info = -15;
    }

    if (*info == 0) {
        nb1 = ilaenv_(&c__1, "ZGEQRF", " ", n, n, &c_n1, &c_n1);
        nb2 = ilaenv_(&c__1, "ZUNMQR", " ", n, n, n, &c_n1);
        nb3 = ilaenv_(&c__1, "ZUNGQR", " ", n, n, n, &c_n1);
/* Computing MAX */
        i__1 = max(nb1,nb2);
        nb = max(i__1,nb3);
/* Computing MAX */
        i__1 = *n << 1, i__2 = *n * (nb + 1);
        lopt = max(i__1,i__2);
        work[1].r = (doublereal) lopt, work[1].i = 0.;
    }

    if (*info != 0) {
        i__1 = -(*info);
        xerbla_("ZGEGV ", &i__1);
        return 0;
    } else if (lquery) {
        return 0;
    }

/*     Quick return if possible */

    if (*n == 0) {
        return 0;
    }

/*     Get machine constants */

    eps = dlamch_("E") * dlamch_("B");
    safmin = dlamch_("S");
    safmin += safmin;
    safmax = 1. / safmin;

/*     Scale A */

    anrm = zlange_("M", n, n, &a[a_offset], lda, &rwork[1]);
    anrm1 = anrm;
    anrm2 = 1.;
    if (anrm < 1.) {
        if (safmax * anrm < 1.) {
            anrm1 = safmin;
            anrm2 = safmax * anrm;
        }
    }

    if (anrm > 0.) {
        zlascl_("G", &c_n1, &c_n1, &anrm, &c_b29, n, n, &a[a_offset], lda, &
                iinfo);
        if (iinfo != 0) {
            *info = *n + 10;
            return 0;
        }
    }

/*     Scale B */

    bnrm = zlange_("M", n, n, &b[b_offset], ldb, &rwork[1]);
    bnrm1 = bnrm;
    bnrm2 = 1.;
    if (bnrm < 1.) {
        if (safmax * bnrm < 1.) {
            bnrm1 = safmin;
            bnrm2 = safmax * bnrm;
        }
    }

    if (bnrm > 0.) {
        zlascl_("G", &c_n1, &c_n1, &bnrm, &c_b29, n, n, &b[b_offset], ldb, &
                iinfo);
        if (iinfo != 0) {
            *info = *n + 10;
            return 0;
        }
    }

/*     Permute the matrix to make it more nearly triangular */
/*     Also "balance" the matrix. */

    ileft = 1;
    iright = *n + 1;
    irwork = iright + *n;
    zggbal_("P", n, &a[a_offset], lda, &b[b_offset], ldb, &ilo, &ihi, &rwork[
            ileft], &rwork[iright], &rwork[irwork], &iinfo);
    if (iinfo != 0) {
        *info = *n + 1;
        goto L80;
    }

/*     Reduce B to triangular form, and initialize VL and/or VR */

    irows = ihi + 1 - ilo;
    if (ilv) {
        icols = *n + 1 - ilo;
    } else {
        icols = irows;
    }
    itau = 1;
    iwork = itau + irows;
    i__1 = *lwork + 1 - iwork;
    zgeqrf_(&irows, &icols, &b[ilo + ilo * b_dim1], ldb, &work[itau], &work[
            iwork], &i__1, &iinfo);
    if (iinfo >= 0) {
/* Computing MAX */
        i__3 = iwork;
        i__1 = lwkopt, i__2 = (integer) work[i__3].r + iwork - 1;
        lwkopt = max(i__1,i__2);
    }
    if (iinfo != 0) {
        *info = *n + 2;
        goto L80;
    }

    i__1 = *lwork + 1 - iwork;
    zunmqr_("L", "C", &irows, &icols, &irows, &b[ilo + ilo * b_dim1], ldb, &
            work[itau], &a[ilo + ilo * a_dim1], lda, &work[iwork], &i__1, &
            iinfo);
    if (iinfo >= 0) {
/* Computing MAX */
        i__3 = iwork;
        i__1 = lwkopt, i__2 = (integer) work[i__3].r + iwork - 1;
        lwkopt = max(i__1,i__2);
    }
    if (iinfo != 0) {
        *info = *n + 3;
        goto L80;
    }

    if (ilvl) {
        zlaset_("Full", n, n, &c_b1, &c_b2, &vl[vl_offset], ldvl);
        i__1 = irows - 1;
        i__2 = irows - 1;
        zlacpy_("L", &i__1, &i__2, &b[ilo + 1 + ilo * b_dim1], ldb, &vl[ilo + 
                1 + ilo * vl_dim1], ldvl);
        i__1 = *lwork + 1 - iwork;
        zungqr_(&irows, &irows, &irows, &vl[ilo + ilo * vl_dim1], ldvl, &work[
                itau], &work[iwork], &i__1, &iinfo);
        if (iinfo >= 0) {
/* Computing MAX */
            i__3 = iwork;
            i__1 = lwkopt, i__2 = (integer) work[i__3].r + iwork - 1;
            lwkopt = max(i__1,i__2);
        }
        if (iinfo != 0) {
            *info = *n + 4;
            goto L80;
        }
    }

    if (ilvr) {
        zlaset_("Full", n, n, &c_b1, &c_b2, &vr[vr_offset], ldvr);
    }

/*     Reduce to generalized Hessenberg form */

    if (ilv) {

/*        Eigenvectors requested -- work on whole matrix. */

        zgghrd_(jobvl, jobvr, n, &ilo, &ihi, &a[a_offset], lda, &b[b_offset], 
                ldb, &vl[vl_offset], ldvl, &vr[vr_offset], ldvr, &iinfo);
    } else {
        zgghrd_("N", "N", &irows, &c__1, &irows, &a[ilo + ilo * a_dim1], lda, 
                &b[ilo + ilo * b_dim1], ldb, &vl[vl_offset], ldvl, &vr[
                vr_offset], ldvr, &iinfo);
    }
    if (iinfo != 0) {
        *info = *n + 5;
        goto L80;
    }

/*     Perform QZ algorithm */

    iwork = itau;
    if (ilv) {
        *(unsigned char *)chtemp = 'S';
    } else {
        *(unsigned char *)chtemp = 'E';
    }
    i__1 = *lwork + 1 - iwork;
    zhgeqz_(chtemp, jobvl, jobvr, n, &ilo, &ihi, &a[a_offset], lda, &b[
            b_offset], ldb, &alpha[1], &beta[1], &vl[vl_offset], ldvl, &vr[
            vr_offset], ldvr, &work[iwork], &i__1, &rwork[irwork], &iinfo);
    if (iinfo >= 0) {
/* Computing MAX */
        i__3 = iwork;
        i__1 = lwkopt, i__2 = (integer) work[i__3].r + iwork - 1;
        lwkopt = max(i__1,i__2);
    }
    if (iinfo != 0) {
        if (iinfo > 0 && iinfo <= *n) {
            *info = iinfo;
        } else if (iinfo > *n && iinfo <= *n << 1) {
            *info = iinfo - *n;
        } else {
            *info = *n + 6;
        }
        goto L80;
    }

    if (ilv) {

/*        Compute Eigenvectors */

        if (ilvl) {
            if (ilvr) {
                *(unsigned char *)chtemp = 'B';
            } else {
                *(unsigned char *)chtemp = 'L';
            }
        } else {
            *(unsigned char *)chtemp = 'R';
        }

        ztgevc_(chtemp, "B", ldumma, n, &a[a_offset], lda, &b[b_offset], ldb, 
                &vl[vl_offset], ldvl, &vr[vr_offset], ldvr, n, &in, &work[
                iwork], &rwork[irwork], &iinfo);
        if (iinfo != 0) {
            *info = *n + 7;
            goto L80;
        }

/*        Undo balancing on VL and VR, rescale */

        if (ilvl) {
            zggbak_("P", "L", n, &ilo, &ihi, &rwork[ileft], &rwork[iright], n, 
                     &vl[vl_offset], ldvl, &iinfo);
            if (iinfo != 0) {
                *info = *n + 8;
                goto L80;
            }
            i__1 = *n;
            for (jc = 1; jc <= i__1; ++jc) {
                temp = 0.;
                i__2 = *n;
                for (jr = 1; jr <= i__2; ++jr) {
/* Computing MAX */
                    i__3 = jr + jc * vl_dim1;
                    d__3 = temp, d__4 = (d__1 = vl[i__3].r, abs(d__1)) + (
                            d__2 = d_imag(&vl[jr + jc * vl_dim1]), abs(d__2));
                    temp = max(d__3,d__4);
/* L10: */
                }
                if (temp < safmin) {
                    goto L30;
                }
                temp = 1. / temp;
                i__2 = *n;
                for (jr = 1; jr <= i__2; ++jr) {
                    i__3 = jr + jc * vl_dim1;
                    i__4 = jr + jc * vl_dim1;
                    z__1.r = temp * vl[i__4].r, z__1.i = temp * vl[i__4].i;
                    vl[i__3].r = z__1.r, vl[i__3].i = z__1.i;
/* L20: */
                }
L30:
                ;
            }
        }
        if (ilvr) {
            zggbak_("P", "R", n, &ilo, &ihi, &rwork[ileft], &rwork[iright], n, 
                     &vr[vr_offset], ldvr, &iinfo);
            if (iinfo != 0) {
                *info = *n + 9;
                goto L80;
            }
            i__1 = *n;
            for (jc = 1; jc <= i__1; ++jc) {
                temp = 0.;
                i__2 = *n;
                for (jr = 1; jr <= i__2; ++jr) {
/* Computing MAX */
                    i__3 = jr + jc * vr_dim1;
                    d__3 = temp, d__4 = (d__1 = vr[i__3].r, abs(d__1)) + (
                            d__2 = d_imag(&vr[jr + jc * vr_dim1]), abs(d__2));
                    temp = max(d__3,d__4);
/* L40: */
                }
                if (temp < safmin) {
                    goto L60;
                }
                temp = 1. / temp;
                i__2 = *n;
                for (jr = 1; jr <= i__2; ++jr) {
                    i__3 = jr + jc * vr_dim1;
                    i__4 = jr + jc * vr_dim1;
                    z__1.r = temp * vr[i__4].r, z__1.i = temp * vr[i__4].i;
                    vr[i__3].r = z__1.r, vr[i__3].i = z__1.i;
/* L50: */
                }
L60:
                ;
            }
        }

/*        End of eigenvector calculation */

    }

/*     Undo scaling in alpha, beta */

/*     Note: this does not give the alpha and beta for the unscaled */
/*     problem. */

/*     Un-scaling is limited to avoid underflow in alpha and beta */
/*     if they are significant. */

    i__1 = *n;
    for (jc = 1; jc <= i__1; ++jc) {
        i__2 = jc;
        absar = (d__1 = alpha[i__2].r, abs(d__1));
        absai = (d__1 = d_imag(&alpha[jc]), abs(d__1));
        i__2 = jc;
        absb = (d__1 = beta[i__2].r, abs(d__1));
        i__2 = jc;
        salfar = anrm * alpha[i__2].r;
        salfai = anrm * d_imag(&alpha[jc]);
        i__2 = jc;
        sbeta = bnrm * beta[i__2].r;
        ilimit = FALSE_;
        scale = 1.;

/*        Check for significant underflow in imaginary part of ALPHA */

/* Computing MAX */
        d__1 = safmin, d__2 = eps * absar, d__1 = max(d__1,d__2), d__2 = eps *
                 absb;
        if (abs(salfai) < safmin && absai >= max(d__1,d__2)) {
            ilimit = TRUE_;
/* Computing MAX */
            d__1 = safmin, d__2 = anrm2 * absai;
            scale = safmin / anrm1 / max(d__1,d__2);
        }

/*        Check for significant underflow in real part of ALPHA */

/* Computing MAX */
        d__1 = safmin, d__2 = eps * absai, d__1 = max(d__1,d__2), d__2 = eps *
                 absb;
        if (abs(salfar) < safmin && absar >= max(d__1,d__2)) {
            ilimit = TRUE_;
/* Computing MAX */
/* Computing MAX */
            d__3 = safmin, d__4 = anrm2 * absar;
            d__1 = scale, d__2 = safmin / anrm1 / max(d__3,d__4);
            scale = max(d__1,d__2);
        }

/*        Check for significant underflow in BETA */

/* Computing MAX */
        d__1 = safmin, d__2 = eps * absar, d__1 = max(d__1,d__2), d__2 = eps *
                 absai;
        if (abs(sbeta) < safmin && absb >= max(d__1,d__2)) {
            ilimit = TRUE_;
/* Computing MAX */
/* Computing MAX */
            d__3 = safmin, d__4 = bnrm2 * absb;
            d__1 = scale, d__2 = safmin / bnrm1 / max(d__3,d__4);
            scale = max(d__1,d__2);
        }

/*        Check for possible overflow when limiting scaling */

        if (ilimit) {
/* Computing MAX */
            d__1 = abs(salfar), d__2 = abs(salfai), d__1 = max(d__1,d__2), 
                    d__2 = abs(sbeta);
            temp = scale * safmin * max(d__1,d__2);
            if (temp > 1.) {
                scale /= temp;
            }
            if (scale < 1.) {
                ilimit = FALSE_;
            }
        }

/*        Recompute un-scaled ALPHA, BETA if necessary. */

        if (ilimit) {
            i__2 = jc;
            salfar = scale * alpha[i__2].r * anrm;
            salfai = scale * d_imag(&alpha[jc]) * anrm;
            i__2 = jc;
            z__2.r = scale * beta[i__2].r, z__2.i = scale * beta[i__2].i;
            z__1.r = bnrm * z__2.r, z__1.i = bnrm * z__2.i;
            sbeta = z__1.r;
        }
        i__2 = jc;
        z__1.r = salfar, z__1.i = salfai;
        alpha[i__2].r = z__1.r, alpha[i__2].i = z__1.i;
        i__2 = jc;
        beta[i__2].r = sbeta, beta[i__2].i = 0.;
/* L70: */
    }

L80:
    work[1].r = (doublereal) lwkopt, work[1].i = 0.;

    return 0;

/*     End of ZGEGV */

} /* zgegv_ */