/* ../netlib/sgges.f -- translated by f2c (version 20100827). 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 "FLA_f2c.h" /* Table of constant values */
static integer c__1 = 1;
static integer c__0 = 0;
static integer c_n1 = -1;
static real c_b38 = 0.f;
static real c_b39 = 1.f;
/* > \brief <b> SGGES computes the eigenvalues, the Schur form, and, optionally, the matrix of Schur vectors f or GE matrices</b> */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download SGGES + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sgges.f "> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sgges.f "> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sgges.f "> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE SGGES( JOBVSL, JOBVSR, SORT, SELCTG, N, A, LDA, B, LDB, */
/* SDIM, ALPHAR, ALPHAI, BETA, VSL, LDVSL, VSR, */
/* LDVSR, WORK, LWORK, BWORK, INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER JOBVSL, JOBVSR, SORT */
/* INTEGER INFO, LDA, LDB, LDVSL, LDVSR, LWORK, N, SDIM */
/* .. */
/* .. Array Arguments .. */
/* LOGICAL BWORK( * ) */
/* REAL A( LDA, * ), ALPHAI( * ), ALPHAR( * ), */
/* $ B( LDB, * ), BETA( * ), VSL( LDVSL, * ), */
/* $ VSR( LDVSR, * ), WORK( * ) */
/* .. */
/* .. Function Arguments .. */
/* LOGICAL SELCTG */
/* EXTERNAL SELCTG */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > SGGES computes for a pair of N-by-N real nonsymmetric matrices (A,B), */
/* > the generalized eigenvalues, the generalized real Schur form (S,T), */
/* > optionally, the left and/or right matrices of Schur vectors (VSL and */
/* > VSR). This gives the generalized Schur factorization */
/* > */
/* > (A,B) = ( (VSL)*S*(VSR)**T, (VSL)*T*(VSR)**T ) */
/* > */
/* > Optionally, it also orders the eigenvalues so that a selected cluster */
/* > of eigenvalues appears in the leading diagonal blocks of the upper */
/* > quasi-triangular matrix S and the upper triangular matrix T.The */
/* > leading columns of VSL and VSR then form an orthonormal basis for the */
/* > corresponding left and right eigenspaces (deflating subspaces). */
/* > */
/* > (If only the generalized eigenvalues are needed, use the driver */
/* > SGGEV instead, which is faster.) */
/* > */
/* > A generalized eigenvalue for a pair of matrices (A,B) is a scalar w */
/* > or a ratio alpha/beta = w, such that A - w*B is singular. It is */
/* > usually represented as the pair (alpha,beta), as there is a */
/* > reasonable interpretation for beta=0 or both being zero. */
/* > */
/* > A pair of matrices (S,T) is in generalized real Schur form if T is */
/* > upper triangular with non-negative diagonal and S is block upper */
/* > triangular with 1-by-1 and 2-by-2 blocks. 1-by-1 blocks correspond */
/* > to real generalized eigenvalues, while 2-by-2 blocks of S will be */
/* > "standardized" by making the corresponding elements of T have the */
/* > form: */
/* > [ a 0 ] */
/* > [ 0 b ] */
/* > */
/* > and the pair of corresponding 2-by-2 blocks in S and T will have a */
/* > complex conjugate pair of generalized eigenvalues. */
/* > */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] JOBVSL */
/* > \verbatim */
/* > JOBVSL is CHARACTER*1 */
/* > = 'N': do not compute the left Schur vectors;
*/
/* > = 'V': compute the left Schur vectors. */
/* > \endverbatim */
/* > */
/* > \param[in] JOBVSR */
/* > \verbatim */
/* > JOBVSR is CHARACTER*1 */
/* > = 'N': do not compute the right Schur vectors;
*/
/* > = 'V': compute the right Schur vectors. */
/* > \endverbatim */
/* > */
/* > \param[in] SORT */
/* > \verbatim */
/* > SORT is CHARACTER*1 */
/* > Specifies whether or not to order the eigenvalues on the */
/* > diagonal of the generalized Schur form. */
/* > = 'N': Eigenvalues are not ordered;
*/
/* > = 'S': Eigenvalues are ordered (see SELCTG);
*/
/* > \endverbatim */
/* > */
/* > \param[in] SELCTG */
/* > \verbatim */
/* > SELCTG is a LOGICAL FUNCTION of three REAL arguments */
/* > SELCTG must be declared EXTERNAL in the calling subroutine. */
/* > If SORT = 'N', SELCTG is not referenced. */
/* > If SORT = 'S', SELCTG is used to select eigenvalues to sort */
/* > to the top left of the Schur form. */
/* > An eigenvalue (ALPHAR(j)+ALPHAI(j))/BETA(j) is selected if */
/* > SELCTG(ALPHAR(j),ALPHAI(j),BETA(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 in the ill-conditioned case, a selected complex */
/* > eigenvalue may no longer satisfy SELCTG(ALPHAR(j),ALPHAI(j), */
/* > BETA(j)) = .TRUE. after ordering. INFO is to be set to N+2 */
/* > in this case. */
/* > \endverbatim */
/* > */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > The order of the matrices A, B, VSL, and VSR. N >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in,out] A */
/* > \verbatim */
/* > A is REAL array, dimension (LDA, N) */
/* > On entry, the first of the pair of matrices. */
/* > On exit, A has been overwritten by its generalized Schur */
/* > form S. */
/* > \endverbatim */
/* > */
/* > \param[in] LDA */
/* > \verbatim */
/* > LDA is INTEGER */
/* > The leading dimension of A. LDA >= max(1,N). */
/* > \endverbatim */
/* > */
/* > \param[in,out] B */
/* > \verbatim */
/* > B is REAL array, dimension (LDB, N) */
/* > On entry, the second of the pair of matrices. */
/* > On exit, B has been overwritten by its generalized Schur */
/* > form T. */
/* > \endverbatim */
/* > */
/* > \param[in] LDB */
/* > \verbatim */
/* > LDB is INTEGER */
/* > The leading dimension of B. LDB >= max(1,N). */
/* > \endverbatim */
/* > */
/* > \param[out] SDIM */
/* > \verbatim */
/* > SDIM is INTEGER */
/* > If SORT = 'N', SDIM = 0. */
/* > If SORT = 'S', SDIM = number of eigenvalues (after sorting) */
/* > for which SELCTG is true. (Complex conjugate pairs for which */
/* > SELCTG is true for either eigenvalue count as 2.) */
/* > \endverbatim */
/* > */
/* > \param[out] ALPHAR */
/* > \verbatim */
/* > ALPHAR is REAL array, dimension (N) */
/* > \endverbatim */
/* > */
/* > \param[out] ALPHAI */
/* > \verbatim */
/* > ALPHAI is REAL array, dimension (N) */
/* > \endverbatim */
/* > */
/* > \param[out] BETA */
/* > \verbatim */
/* > BETA is REAL array, dimension (N) */
/* > On exit, (ALPHAR(j) + ALPHAI(j)*i)/BETA(j), j=1,...,N, will */
/* > be the generalized eigenvalues. ALPHAR(j) + ALPHAI(j)*i, */
/* > and BETA(j),j=1,...,N are the diagonals of the complex Schur */
/* > form (S,T) that would result if the 2-by-2 diagonal blocks of */
/* > the real Schur form of (A,B) were further reduced to */
/* > triangular form using 2-by-2 complex unitary transformations. */
/* > If ALPHAI(j) is zero, then the j-th eigenvalue is real;
if */
/* > positive, then the j-th and (j+1)-st eigenvalues are a */
/* > complex conjugate pair, with ALPHAI(j+1) negative. */
/* > */
/* > Note: the quotients ALPHAR(j)/BETA(j) and ALPHAI(j)/BETA(j) */
/* > may easily over- or underflow, and BETA(j) may even be zero. */
/* > Thus, the user should avoid naively computing the ratio. */
/* > However, ALPHAR and ALPHAI will be always less than and */
/* > usually comparable with norm(A) in magnitude, and BETA always */
/* > less than and usually comparable with norm(B). */
/* > \endverbatim */
/* > */
/* > \param[out] VSL */
/* > \verbatim */
/* > VSL is REAL array, dimension (LDVSL,N) */
/* > If JOBVSL = 'V', VSL will contain the left Schur vectors. */
/* > Not referenced if JOBVSL = 'N'. */
/* > \endverbatim */
/* > */
/* > \param[in] LDVSL */
/* > \verbatim */
/* > LDVSL is INTEGER */
/* > The leading dimension of the matrix VSL. LDVSL >=1, and */
/* > if JOBVSL = 'V', LDVSL >= N. */
/* > \endverbatim */
/* > */
/* > \param[out] VSR */
/* > \verbatim */
/* > VSR is REAL array, dimension (LDVSR,N) */
/* > If JOBVSR = 'V', VSR will contain the right Schur vectors. */
/* > Not referenced if JOBVSR = 'N'. */
/* > \endverbatim */
/* > */
/* > \param[in] LDVSR */
/* > \verbatim */
/* > LDVSR is INTEGER */
/* > The leading dimension of the matrix VSR. LDVSR >= 1, and */
/* > if JOBVSR = 'V', LDVSR >= N. */
/* > \endverbatim */
/* > */
/* > \param[out] WORK */
/* > \verbatim */
/* > WORK is REAL array, dimension (MAX(1,LWORK)) */
/* > On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
/* > \endverbatim */
/* > */
/* > \param[in] LWORK */
/* > \verbatim */
/* > LWORK is INTEGER */
/* > The dimension of the array WORK. */
/* > If N = 0, LWORK >= 1, else LWORK >= max(8*N,6*N+16). */
/* > 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. */
/* > \endverbatim */
/* > */
/* > \param[out] BWORK */
/* > \verbatim */
/* > BWORK is LOGICAL array, dimension (N) */
/* > Not referenced if SORT = 'N'. */
/* > \endverbatim */
/* > */
/* > \param[out] INFO */
/* > \verbatim */
/* > INFO is INTEGER */
/* > = 0: successful exit */
/* > < 0: if INFO = -i, the i-th argument had an illegal value. */
/* > = 1,...,N: */
/* > The QZ iteration failed. (A,B) are not in Schur */
/* > form, but ALPHAR(j), ALPHAI(j), and BETA(j) should */
/* > be correct for j=INFO+1,...,N. */
/* > > N: =N+1: other than QZ iteration failed in SHGEQZ. */
/* > =N+2: after reordering, roundoff changed values of */
/* > some complex eigenvalues so that leading */
/* > eigenvalues in the Generalized Schur form no */
/* > longer satisfy SELCTG=.TRUE. This could also */
/* > be caused due to scaling. */
/* > =N+3: reordering failed in STGSEN. */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \date November 2011 */
/* > \ingroup realGEeigen */
/* ===================================================================== */
/* Subroutine */
int sgges_(char *jobvsl, char *jobvsr, char *sort, L_fp selctg, integer *n, real *a, integer *lda, real *b, integer *ldb, integer *sdim, real *alphar, real *alphai, real *beta, real *vsl, integer *ldvsl, real *vsr, integer *ldvsr, real *work, integer *lwork, logical *bwork, integer *info)
{
    /* System generated locals */
    integer a_dim1, a_offset, b_dim1, b_offset, vsl_dim1, vsl_offset, vsr_dim1, vsr_offset, i__1, i__2;
    real r__1;
    /* Builtin functions */
    double sqrt(doublereal);
    /* Local variables */
    integer i__, ip;
    real dif[2];
    integer ihi, ilo;
    real eps, anrm, bnrm;
    integer idum[1], ierr, itau, iwrk;
    real pvsl, pvsr;
    extern logical lsame_(char *, char *);
    integer ileft, icols;
    logical cursl, ilvsl, ilvsr;
    integer irows;
    logical lst2sl;
    extern /* Subroutine */
    int slabad_(real *, real *), sggbak_(char *, char *, integer *, integer *, integer *, real *, real *, integer *, real *, integer *, integer *), sggbal_(char *, integer *, real *, integer *, real *, integer *, integer *, integer *, real *, real *, real *, integer *);
    logical ilascl, ilbscl;
    extern real slamch_(char *), slange_(char *, integer *, integer *, real *, integer *, real *);
    real safmin;
    extern /* Subroutine */
    int sgghrd_(char *, char *, integer *, integer *, integer *, real *, integer *, real *, integer *, real *, integer * , real *, integer *, integer *);
    real safmax;
    extern /* Subroutine */
    int xerbla_(char *, integer *);
    real bignum;
    extern /* Subroutine */
    int slascl_(char *, integer *, integer *, real *, real *, integer *, integer *, real *, integer *, integer *);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *);
    integer ijobvl, iright;
    extern /* Subroutine */
    int sgeqrf_(integer *, integer *, real *, integer *, real *, real *, integer *, integer *);
    integer ijobvr;
    extern /* Subroutine */
    int slacpy_(char *, integer *, integer *, real *, integer *, real *, integer *), slaset_(char *, integer *, integer *, real *, real *, real *, integer *);
    real anrmto, bnrmto;
    logical lastsl;
    extern /* Subroutine */
    int shgeqz_(char *, char *, char *, integer *, integer *, integer *, real *, integer *, real *, integer *, real * , real *, real *, real *, integer *, real *, integer *, real *, integer *, integer *), stgsen_(integer *, logical *, logical *, logical *, integer *, real *, integer *, real *, integer *, real *, real *, real *, real *, integer *, real *, integer *, integer *, real *, real *, real *, real *, integer *, integer *, integer *, integer *);
    integer minwrk, maxwrk;
    real smlnum;
    extern /* Subroutine */
    int sorgqr_(integer *, integer *, integer *, real *, integer *, real *, real *, integer *, integer *);
    logical wantst, lquery;
    extern /* Subroutine */
    int sormqr_(char *, char *, integer *, integer *, integer *, real *, integer *, real *, real *, integer *, real *, integer *, integer *);
    /* -- LAPACK driver routine (version 3.4.0) -- */
    /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
    /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
    /* November 2011 */
    /* .. Scalar Arguments .. */
    /* .. */
    /* .. Array Arguments .. */
    /* .. */
    /* .. Function Arguments .. */
    /* .. */
    /* ===================================================================== */
    /* .. Parameters .. */
    /* .. */
    /* .. Local Scalars .. */
    /* .. */
    /* .. Local Arrays .. */
    /* .. */
    /* .. External Subroutines .. */
    /* .. */
    /* .. External Functions .. */
    /* .. */
    /* .. Intrinsic Functions .. */
    /* .. */
    /* .. 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;
    --alphar;
    --alphai;
    --beta;
    vsl_dim1 = *ldvsl;
    vsl_offset = 1 + vsl_dim1;
    vsl -= vsl_offset;
    vsr_dim1 = *ldvsr;
    vsr_offset = 1 + vsr_dim1;
    vsr -= vsr_offset;
    --work;
    --bwork;
    /* Function Body */
    if (lsame_(jobvsl, "N"))
    {
        ijobvl = 1;
        ilvsl = FALSE_;
    }
    else if (lsame_(jobvsl, "V"))
    {
        ijobvl = 2;
        ilvsl = TRUE_;
    }
    else
    {
        ijobvl = -1;
        ilvsl = FALSE_;
    }
    if (lsame_(jobvsr, "N"))
    {
        ijobvr = 1;
        ilvsr = FALSE_;
    }
    else if (lsame_(jobvsr, "V"))
    {
        ijobvr = 2;
        ilvsr = TRUE_;
    }
    else
    {
        ijobvr = -1;
        ilvsr = FALSE_;
    }
    wantst = lsame_(sort, "S");
    /* Test the input arguments */
    *info = 0;
    lquery = *lwork == -1;
    if (ijobvl <= 0)
    {
        *info = -1;
    }
    else if (ijobvr <= 0)
    {
        *info = -2;
    }
    else if (! wantst && ! lsame_(sort, "N"))
    {
        *info = -3;
    }
    else if (*n < 0)
    {
        *info = -5;
    }
    else if (*lda < max(1,*n))
    {
        *info = -7;
    }
    else if (*ldb < max(1,*n))
    {
        *info = -9;
    }
    else if (*ldvsl < 1 || ilvsl && *ldvsl < *n)
    {
        *info = -15;
    }
    else if (*ldvsr < 1 || ilvsr && *ldvsr < *n)
    {
        *info = -17;
    }
    /* 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.) */
    if (*info == 0)
    {
        if (*n > 0)
        {
            /* Computing MAX */
            i__1 = *n << 3;
            i__2 = *n * 6 + 16; // , expr subst
            minwrk = max(i__1,i__2);
            maxwrk = minwrk - *n + *n * ilaenv_(&c__1, "SGEQRF", " ", n, & c__1, n, &c__0);
            /* Computing MAX */
            i__1 = maxwrk;
            i__2 = minwrk - *n + *n * ilaenv_(&c__1, "SORMQR", " ", n, &c__1, n, &c_n1); // , expr subst
            maxwrk = max(i__1,i__2);
            if (ilvsl)
            {
                /* Computing MAX */
                i__1 = maxwrk;
                i__2 = minwrk - *n + *n * ilaenv_(&c__1, "SOR" "GQR", " ", n, &c__1, n, &c_n1); // , expr subst
                maxwrk = max(i__1,i__2);
            }
        }
        else
        {
            minwrk = 1;
            maxwrk = 1;
        }
        work[1] = (real) maxwrk;
        if (*lwork < minwrk && ! lquery)
        {
            *info = -19;
        }
    }
    if (*info != 0)
    {
        i__1 = -(*info);
        xerbla_("SGGES ", &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");
    safmin = slamch_("S");
    safmax = 1.f / safmin;
    slabad_(&safmin, &safmax);
    smlnum = sqrt(safmin) / eps;
    bignum = 1.f / smlnum;
    /* Scale A if max element outside range [SMLNUM,BIGNUM] */
    anrm = slange_("M", n, n, &a[a_offset], lda, &work[1]);
    ilascl = FALSE_;
    if (anrm > 0.f && anrm < smlnum)
    {
        anrmto = smlnum;
        ilascl = TRUE_;
    }
    else if (anrm > bignum)
    {
        anrmto = bignum;
        ilascl = TRUE_;
    }
    if (ilascl)
    {
        slascl_("G", &c__0, &c__0, &anrm, &anrmto, n, n, &a[a_offset], lda, & ierr);
    }
    /* Scale B if max element outside range [SMLNUM,BIGNUM] */
    bnrm = slange_("M", n, n, &b[b_offset], ldb, &work[1]);
    ilbscl = FALSE_;
    if (bnrm > 0.f && bnrm < smlnum)
    {
        bnrmto = smlnum;
        ilbscl = TRUE_;
    }
    else if (bnrm > bignum)
    {
        bnrmto = bignum;
        ilbscl = TRUE_;
    }
    if (ilbscl)
    {
        slascl_("G", &c__0, &c__0, &bnrm, &bnrmto, n, n, &b[b_offset], ldb, & ierr);
    }
    /* Permute the matrix to make it more nearly triangular */
    /* (Workspace: need 6*N + 2*N space for storing balancing factors) */
    ileft = 1;
    iright = *n + 1;
    iwrk = iright + *n;
    sggbal_("P", n, &a[a_offset], lda, &b[b_offset], ldb, &ilo, &ihi, &work[ ileft], &work[iright], &work[iwrk], &ierr);
    /* Reduce B to triangular form (QR decomposition of B) */
    /* (Workspace: need N, prefer N*NB) */
    irows = ihi + 1 - ilo;
    icols = *n + 1 - ilo;
    itau = iwrk;
    iwrk = itau + irows;
    i__1 = *lwork + 1 - iwrk;
    sgeqrf_(&irows, &icols, &b[ilo + ilo * b_dim1], ldb, &work[itau], &work[ iwrk], &i__1, &ierr);
    /* Apply the orthogonal transformation to matrix A */
    /* (Workspace: need N, prefer N*NB) */
    i__1 = *lwork + 1 - iwrk;
    sormqr_("L", "T", &irows, &icols, &irows, &b[ilo + ilo * b_dim1], ldb, & work[itau], &a[ilo + ilo * a_dim1], lda, &work[iwrk], &i__1, & ierr);
    /* Initialize VSL */
    /* (Workspace: need N, prefer N*NB) */
    if (ilvsl)
    {
        slaset_("Full", n, n, &c_b38, &c_b39, &vsl[vsl_offset], ldvsl);
        if (irows > 1)
        {
            i__1 = irows - 1;
            i__2 = irows - 1;
            slacpy_("L", &i__1, &i__2, &b[ilo + 1 + ilo * b_dim1], ldb, &vsl[ ilo + 1 + ilo * vsl_dim1], ldvsl);
        }
        i__1 = *lwork + 1 - iwrk;
        sorgqr_(&irows, &irows, &irows, &vsl[ilo + ilo * vsl_dim1], ldvsl, & work[itau], &work[iwrk], &i__1, &ierr);
    }
    /* Initialize VSR */
    if (ilvsr)
    {
        slaset_("Full", n, n, &c_b38, &c_b39, &vsr[vsr_offset], ldvsr);
    }
    /* Reduce to generalized Hessenberg form */
    /* (Workspace: none needed) */
    sgghrd_(jobvsl, jobvsr, n, &ilo, &ihi, &a[a_offset], lda, &b[b_offset], ldb, &vsl[vsl_offset], ldvsl, &vsr[vsr_offset], ldvsr, &ierr);
    /* Perform QZ algorithm, computing Schur vectors if desired */
    /* (Workspace: need N) */
    iwrk = itau;
    i__1 = *lwork + 1 - iwrk;
    shgeqz_("S", jobvsl, jobvsr, n, &ilo, &ihi, &a[a_offset], lda, &b[ b_offset], ldb, &alphar[1], &alphai[1], &beta[1], &vsl[vsl_offset] , ldvsl, &vsr[vsr_offset], ldvsr, &work[iwrk], &i__1, &ierr);
    if (ierr != 0)
    {
        if (ierr > 0 && ierr <= *n)
        {
            *info = ierr;
        }
        else if (ierr > *n && ierr <= *n << 1)
        {
            *info = ierr - *n;
        }
        else
        {
            *info = *n + 1;
        }
        goto L40;
    }
    /* Sort eigenvalues ALPHA/BETA if desired */
    /* (Workspace: need 4*N+16 ) */
    *sdim = 0;
    if (wantst)
    {
        /* Undo scaling on eigenvalues before SELCTGing */
        if (ilascl)
        {
            slascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphar[1], n, &ierr);
            slascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphai[1], n, &ierr);
        }
        if (ilbscl)
        {
            slascl_("G", &c__0, &c__0, &bnrmto, &bnrm, n, &c__1, &beta[1], n, &ierr);
        }
        /* Select eigenvalues */
        i__1 = *n;
        for (i__ = 1;
                i__ <= i__1;
                ++i__)
        {
            bwork[i__] = (*selctg)(&alphar[i__], &alphai[i__], &beta[i__]);
            /* L10: */
        }
        i__1 = *lwork - iwrk + 1;
        stgsen_(&c__0, &ilvsl, &ilvsr, &bwork[1], n, &a[a_offset], lda, &b[ b_offset], ldb, &alphar[1], &alphai[1], &beta[1], &vsl[ vsl_offset], ldvsl, &vsr[vsr_offset], ldvsr, sdim, &pvsl, & pvsr, dif, &work[iwrk], &i__1, idum, &c__1, &ierr);
        if (ierr == 1)
        {
            *info = *n + 3;
        }
    }
    /* Apply back-permutation to VSL and VSR */
    /* (Workspace: none needed) */
    if (ilvsl)
    {
        sggbak_("P", "L", n, &ilo, &ihi, &work[ileft], &work[iright], n, &vsl[ vsl_offset], ldvsl, &ierr);
    }
    if (ilvsr)
    {
        sggbak_("P", "R", n, &ilo, &ihi, &work[ileft], &work[iright], n, &vsr[ vsr_offset], ldvsr, &ierr);
    }
    /* Check if unscaling would cause over/underflow, if so, rescale */
    /* (ALPHAR(I),ALPHAI(I),BETA(I)) so BETA(I) is on the order of */
    /* B(I,I) and ALPHAR(I) and ALPHAI(I) are on the order of A(I,I) */
    if (ilascl)
    {
        i__1 = *n;
        for (i__ = 1;
                i__ <= i__1;
                ++i__)
        {
            if (alphai[i__] != 0.f)
            {
                if (alphar[i__] / safmax > anrmto / anrm || safmin / alphar[ i__] > anrm / anrmto)
                {
                    work[1] = (r__1 = a[i__ + i__ * a_dim1] / alphar[i__], f2c_abs(r__1));
                    beta[i__] *= work[1];
                    alphar[i__] *= work[1];
                    alphai[i__] *= work[1];
                }
                else if (alphai[i__] / safmax > anrmto / anrm || safmin / alphai[i__] > anrm / anrmto)
                {
                    work[1] = (r__1 = a[i__ + (i__ + 1) * a_dim1] / alphai[ i__], f2c_abs(r__1));
                    beta[i__] *= work[1];
                    alphar[i__] *= work[1];
                    alphai[i__] *= work[1];
                }
            }
            /* L50: */
        }
    }
    if (ilbscl)
    {
        i__1 = *n;
        for (i__ = 1;
                i__ <= i__1;
                ++i__)
        {
            if (alphai[i__] != 0.f)
            {
                if (beta[i__] / safmax > bnrmto / bnrm || safmin / beta[i__] > bnrm / bnrmto)
                {
                    work[1] = (r__1 = b[i__ + i__ * b_dim1] / beta[i__], f2c_abs( r__1));
                    beta[i__] *= work[1];
                    alphar[i__] *= work[1];
                    alphai[i__] *= work[1];
                }
            }
            /* L60: */
        }
    }
    /* Undo scaling */
    if (ilascl)
    {
        slascl_("H", &c__0, &c__0, &anrmto, &anrm, n, n, &a[a_offset], lda, & ierr);
        slascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphar[1], n, & ierr);
        slascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphai[1], n, & ierr);
    }
    if (ilbscl)
    {
        slascl_("U", &c__0, &c__0, &bnrmto, &bnrm, n, n, &b[b_offset], ldb, & ierr);
        slascl_("G", &c__0, &c__0, &bnrmto, &bnrm, n, &c__1, &beta[1], n, & ierr);
    }
    if (wantst)
    {
        /* Check if reordering is correct */
        lastsl = TRUE_;
        lst2sl = TRUE_;
        *sdim = 0;
        ip = 0;
        i__1 = *n;
        for (i__ = 1;
                i__ <= i__1;
                ++i__)
        {
            cursl = (*selctg)(&alphar[i__], &alphai[i__], &beta[i__]);
            if (alphai[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: */
        }
    }
L40:
    work[1] = (real) maxwrk;
    return 0;
    /* End of SGGES */
}
/* sgges_ */