#include "blaswrap.h"
#include "f2c.h"

/* Subroutine */ int dggesx_(char *jobvsl, char *jobvsr, char *sort, L_fp 
	selctg, char *sense, integer *n, doublereal *a, integer *lda, 
	doublereal *b, integer *ldb, integer *sdim, doublereal *alphar, 
	doublereal *alphai, doublereal *beta, doublereal *vsl, integer *ldvsl,
	 doublereal *vsr, integer *ldvsr, doublereal *rconde, doublereal *
	rcondv, doublereal *work, integer *lwork, integer *iwork, integer * 	liwork, logical *bwork, integer *info  	)
{
/*  -- LAPACK driver routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    DGGESX computes for a pair of N-by-N real nonsymmetric matrices   
    (A,B), the generalized eigenvalues, the real Schur form (S,T), and,   
    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; computes   
    a reciprocal condition number for the average of the selected   
    eigenvalues (RCONDE); and computes a reciprocal condition number for   
    the right and left deflating subspaces corresponding to the selected   
    eigenvalues (RCONDV). The leading columns of VSL and VSR then form   
    an orthonormal basis for the corresponding left and right eigenspaces   
    (deflating subspaces).   

    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 for 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.   


    Arguments   
    =========   

    JOBVSL  (input) CHARACTER*1   
            = 'N':  do not compute the left Schur vectors;   
            = 'V':  compute the left Schur vectors.   

    JOBVSR  (input) CHARACTER*1   
            = 'N':  do not compute the right Schur vectors;   
            = 'V':  compute the right Schur vectors.   

    SORT    (input) 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).   

    SELCTG  (external procedure) LOGICAL FUNCTION of three DOUBLE PRECISION 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 a selected complex eigenvalue may no longer satisfy   
            SELCTG(ALPHAR(j),ALPHAI(j),BETA(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+3.   

    SENSE   (input) CHARACTER*1   
            Determines which reciprocal condition numbers are computed.   
            = 'N' : None are computed;   
            = 'E' : Computed for average of selected eigenvalues only;   
            = 'V' : Computed for selected deflating subspaces only;   
            = 'B' : Computed for both.   
            If SENSE = 'E', 'V', or 'B', SORT must equal 'S'.   

    N       (input) INTEGER   
            The order of the matrices A, B, VSL, and VSR.  N >= 0.   

    A       (input/output) DOUBLE PRECISION 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.   

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

    B       (input/output) DOUBLE PRECISION 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.   

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

    SDIM    (output) 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.)   

    ALPHAR  (output) DOUBLE PRECISION array, dimension (N)   
    ALPHAI  (output) DOUBLE PRECISION array, dimension (N)   
    BETA    (output) DOUBLE PRECISION 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).   

    VSL     (output) DOUBLE PRECISION array, dimension (LDVSL,N)   
            If JOBVSL = 'V', VSL will contain the left Schur vectors.   
            Not referenced if JOBVSL = 'N'.   

    LDVSL   (input) INTEGER   
            The leading dimension of the matrix VSL. LDVSL >=1, and   
            if JOBVSL = 'V', LDVSL >= N.   

    VSR     (output) DOUBLE PRECISION array, dimension (LDVSR,N)   
            If JOBVSR = 'V', VSR will contain the right Schur vectors.   
            Not referenced if JOBVSR = 'N'.   

    LDVSR   (input) INTEGER   
            The leading dimension of the matrix VSR. LDVSR >= 1, and   
            if JOBVSR = 'V', LDVSR >= N.   

    RCONDE  (output) DOUBLE PRECISION array, dimension ( 2 )   
            If SENSE = 'E' or 'B', RCONDE(1) and RCONDE(2) contain the   
            reciprocal condition numbers for the average of the selected   
            eigenvalues.   
            Not referenced if SENSE = 'N' or 'V'.   

    RCONDV  (output) DOUBLE PRECISION array, dimension ( 2 )   
            If SENSE = 'V' or 'B', RCONDV(1) and RCONDV(2) contain the   
            reciprocal condition numbers for the selected deflating   
            subspaces.   
            Not referenced if SENSE = 'N' or 'E'.   

    WORK    (workspace/output) DOUBLE PRECISION 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.   
            If N = 0, LWORK >= 1, else if SENSE = 'E', 'V', or 'B',   
            LWORK >= max( 8*N, 6*N+16, 2*SDIM*(N-SDIM) ), else   
            LWORK >= max( 8*N, 6*N+16 ).   
            Note that 2*SDIM*(N-SDIM) <= N*N/2.   
            Note also that an error is only returned if   
            LWORK < max( 8*N, 6*N+16), but if SENSE = 'E' or 'V' or 'B'   
            this may not be large enough.   

            If LWORK = -1, then a workspace query is assumed; the routine   
            only calculates the bound on the optimal size of the WORK   
            array and the minimum size of the IWORK array, returns these   
            values as the first entries of the WORK and IWORK arrays, and   
            no error message related to LWORK or LIWORK is issued by   
            XERBLA.   

    IWORK   (workspace) INTEGER array, dimension (MAX(1,LIWORK))   
            On exit, if INFO = 0, IWORK(1) returns the minimum LIWORK.   

    LIWORK  (input) INTEGER   
            The dimension of the array IWORK.   
            If SENSE = 'N' or N = 0, LIWORK >= 1, otherwise   
            LIWORK >= N+6.   

            If LIWORK = -1, then a workspace query is assumed; the   
            routine only calculates the bound on the optimal size of the   
            WORK array and the minimum size of the IWORK array, returns   
            these values as the first entries of the WORK and IWORK   
            arrays, and no error message related to LWORK or LIWORK 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.   
            = 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 DHGEQZ   
                  =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 DTGSEN.   

    Further details   
    ===============   

    An approximate (asymptotic) bound on the average absolute error of   
    the selected eigenvalues is   

         EPS * norm((A, B)) / RCONDE( 1 ).   

    An approximate (asymptotic) bound on the maximum angular error in   
    the computed deflating subspaces is   

         EPS * norm((A, B)) / RCONDV( 2 ).   

    See LAPACK User's Guide, section 4.11 for more information.   

    =====================================================================   


       Decode the input arguments   

       Parameter adjustments */
    /* Table of constant values */
    static integer c__1 = 1;
    static integer c__0 = 0;
    static integer c_n1 = -1;
    static doublereal c_b42 = 0.;
    static doublereal c_b43 = 1.;
    
    /* System generated locals */
    integer a_dim1, a_offset, b_dim1, b_offset, vsl_dim1, vsl_offset, 
	    vsr_dim1, vsr_offset, i__1, i__2;
    doublereal d__1;
    /* Builtin functions */
    double sqrt(doublereal);
    /* Local variables */
    static integer i__, ip;
    static doublereal pl, pr, dif[2];
    static integer ihi, ilo;
    static doublereal eps;
    static integer ijob;
    static doublereal anrm, bnrm;
    static integer ierr, itau, iwrk, lwrk;
    extern logical lsame_(char *, char *);
    static integer ileft, icols;
    static logical cursl, ilvsl, ilvsr;
    static integer irows;
    extern /* Subroutine */ int dlabad_(doublereal *, doublereal *), dggbak_(
	    char *, char *, integer *, integer *, integer *, doublereal *, 
	    doublereal *, integer *, doublereal *, integer *, integer *), dggbal_(char *, integer *, doublereal *, integer 
	    *, doublereal *, integer *, integer *, integer *, doublereal *, 
	    doublereal *, doublereal *, integer *);
    static logical lst2sl;
    extern doublereal dlamch_(char *), dlange_(char *, integer *, 
	    integer *, doublereal *, integer *, doublereal *);
    extern /* Subroutine */ int dgghrd_(char *, char *, integer *, integer *, 
	    integer *, doublereal *, integer *, doublereal *, integer *, 
	    doublereal *, integer *, doublereal *, integer *, integer *), dlascl_(char *, integer *, integer *, doublereal 
	    *, doublereal *, integer *, integer *, doublereal *, integer *, 
	    integer *);
    static logical ilascl, ilbscl;
    extern /* Subroutine */ int dgeqrf_(integer *, integer *, doublereal *, 
	    integer *, doublereal *, doublereal *, integer *, integer *), 
	    dlacpy_(char *, integer *, integer *, doublereal *, integer *, 
	    doublereal *, integer *);
    static doublereal safmin;
    extern /* Subroutine */ int dlaset_(char *, integer *, integer *, 
	    doublereal *, doublereal *, doublereal *, integer *);
    static doublereal safmax;
    extern /* Subroutine */ int xerbla_(char *, integer *);
    static doublereal bignum;
    extern /* Subroutine */ int dhgeqz_(char *, char *, char *, integer *, 
	    integer *, integer *, doublereal *, integer *, doublereal *, 
	    integer *, doublereal *, doublereal *, doublereal *, doublereal *,
	     integer *, doublereal *, integer *, doublereal *, integer *, 
	    integer *);
    static integer ijobvl, iright;
    extern /* Subroutine */ int dtgsen_(integer *, logical *, logical *, 
	    logical *, integer *, doublereal *, integer *, doublereal *, 
	    integer *, doublereal *, doublereal *, doublereal *, doublereal *,
	     integer *, doublereal *, integer *, integer *, doublereal *, 
	    doublereal *, doublereal *, doublereal *, integer *, integer *, 
	    integer *, integer *);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
	    integer *, integer *, ftnlen, ftnlen);
    static integer ijobvr;
    static logical wantsb;
    static integer liwmin;
    static logical wantse, lastsl;
    static doublereal anrmto, bnrmto;
    extern /* Subroutine */ int dorgqr_(integer *, integer *, integer *, 
	    doublereal *, integer *, doublereal *, doublereal *, integer *, 
	    integer *);
    static integer minwrk, maxwrk;
    static logical wantsn;
    static doublereal smlnum;
    extern /* Subroutine */ int dormqr_(char *, char *, integer *, integer *, 
	    integer *, doublereal *, integer *, doublereal *, doublereal *, 
	    integer *, doublereal *, integer *, integer *);
    static logical wantst, lquery, wantsv;


    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;
    --rconde;
    --rcondv;
    --work;
    --iwork;
    --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");
    wantsn = lsame_(sense, "N");
    wantse = lsame_(sense, "E");
    wantsv = lsame_(sense, "V");
    wantsb = lsame_(sense, "B");
    lquery = *lwork == -1 || *liwork == -1;
    if (wantsn) {
	ijob = 0;
    } else if (wantse) {
	ijob = 1;
    } else if (wantsv) {
	ijob = 2;
    } else if (wantsb) {
	ijob = 4;
    }

/*     Test the input arguments */

    *info = 0;
    if (ijobvl <= 0) {
	*info = -1;
    } else if (ijobvr <= 0) {
	*info = -2;
    } else if (! wantst && ! lsame_(sort, "N")) {
	*info = -3;
    } else if (! (wantsn || wantse || wantsv || wantsb) || ! wantst && ! 
	    wantsn) {
	*info = -5;
    } else if (*n < 0) {
	*info = -6;
    } else if (*lda < max(1,*n)) {
	*info = -8;
    } else if (*ldb < max(1,*n)) {
	*info = -10;
    } else if (*ldvsl < 1 || ilvsl && *ldvsl < *n) {
	*info = -16;
    } else if (*ldvsr < 1 || ilvsr && *ldvsr < *n) {
	*info = -18;
    }

/*     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;
	    minwrk = max(i__1,i__2);
	    maxwrk = minwrk - *n + *n * ilaenv_(&c__1, "DGEQRF", " ", n, &
		    c__1, n, &c__0, (ftnlen)6, (ftnlen)1);
/* Computing MAX */
	    i__1 = maxwrk, i__2 = minwrk - *n + *n * ilaenv_(&c__1, "DORMQR", 
		    " ", n, &c__1, n, &c_n1, (ftnlen)6, (ftnlen)1);
	    maxwrk = max(i__1,i__2);
	    if (ilvsl) {
/* Computing MAX */
		i__1 = maxwrk, i__2 = minwrk - *n + *n * ilaenv_(&c__1, "DOR"
			"GQR", " ", n, &c__1, n, &c_n1, (ftnlen)6, (ftnlen)1);
		maxwrk = max(i__1,i__2);
	    }
	    lwrk = maxwrk;
	    if (ijob >= 1) {
/* Computing MAX */
		i__1 = lwrk, i__2 = *n * *n / 2;
		lwrk = max(i__1,i__2);
	    }
	} else {
	    minwrk = 1;
	    maxwrk = 1;
	    lwrk = 1;
	}
	work[1] = (doublereal) lwrk;
	if (wantsn || *n == 0) {
	    liwmin = 1;
	} else {
	    liwmin = *n + 6;
	}
	iwork[1] = liwmin;

	if (*lwork < minwrk && ! lquery) {
	    *info = -22;
	} else if (*liwork < liwmin && ! lquery) {
	    *info = -24;
	}
    }

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

/*     Quick return if possible */

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

/*     Get machine constants */

    eps = dlamch_("P");
    safmin = dlamch_("S");
    safmax = 1. / safmin;
    dlabad_(&safmin, &safmax);
    smlnum = sqrt(safmin) / eps;
    bignum = 1. / smlnum;

/*     Scale A if max element outside range [SMLNUM,BIGNUM] */

    anrm = dlange_("M", n, n, &a[a_offset], lda, &work[1]);
    ilascl = FALSE_;
    if (anrm > 0. && anrm < smlnum) {
	anrmto = smlnum;
	ilascl = TRUE_;
    } else if (anrm > bignum) {
	anrmto = bignum;
	ilascl = TRUE_;
    }
    if (ilascl) {
	dlascl_("G", &c__0, &c__0, &anrm, &anrmto, n, n, &a[a_offset], lda, &
		ierr);
    }

/*     Scale B if max element outside range [SMLNUM,BIGNUM] */

    bnrm = dlange_("M", n, n, &b[b_offset], ldb, &work[1]);
    ilbscl = FALSE_;
    if (bnrm > 0. && bnrm < smlnum) {
	bnrmto = smlnum;
	ilbscl = TRUE_;
    } else if (bnrm > bignum) {
	bnrmto = bignum;
	ilbscl = TRUE_;
    }
    if (ilbscl) {
	dlascl_("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 for permutation parameters) */

    ileft = 1;
    iright = *n + 1;
    iwrk = iright + *n;
    dggbal_("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;
    dgeqrf_(&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;
    dormqr_("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) {
	dlaset_("Full", n, n, &c_b42, &c_b43, &vsl[vsl_offset], ldvsl);
	if (irows > 1) {
	    i__1 = irows - 1;
	    i__2 = irows - 1;
	    dlacpy_("L", &i__1, &i__2, &b[ilo + 1 + ilo * b_dim1], ldb, &vsl[
		    ilo + 1 + ilo * vsl_dim1], ldvsl);
	}
	i__1 = *lwork + 1 - iwrk;
	dorgqr_(&irows, &irows, &irows, &vsl[ilo + ilo * vsl_dim1], ldvsl, &
		work[itau], &work[iwrk], &i__1, &ierr);
    }

/*     Initialize VSR */

    if (ilvsr) {
	dlaset_("Full", n, n, &c_b42, &c_b43, &vsr[vsr_offset], ldvsr);
    }

/*     Reduce to generalized Hessenberg form   
       (Workspace: none needed) */

    dgghrd_(jobvsl, jobvsr, n, &ilo, &ihi, &a[a_offset], lda, &b[b_offset], 
	    ldb, &vsl[vsl_offset], ldvsl, &vsr[vsr_offset], ldvsr, &ierr);

    *sdim = 0;

/*     Perform QZ algorithm, computing Schur vectors if desired   
       (Workspace: need N) */

    iwrk = itau;
    i__1 = *lwork + 1 - iwrk;
    dhgeqz_("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 L60;
    }

/*     Sort eigenvalues ALPHA/BETA and compute the reciprocal of   
       condition number(s)   
       (Workspace: If IJOB >= 1, need MAX( 8*(N+1), 2*SDIM*(N-SDIM) )   
                   otherwise, need 8*(N+1) ) */

    if (wantst) {

/*        Undo scaling on eigenvalues before SELCTGing */

	if (ilascl) {
	    dlascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphar[1], 
		    n, &ierr);
	    dlascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphai[1], 
		    n, &ierr);
	}
	if (ilbscl) {
	    dlascl_("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: */
	}

/*        Reorder eigenvalues, transform Generalized Schur vectors, and   
          compute reciprocal condition numbers */

	i__1 = *lwork - iwrk + 1;
	dtgsen_(&ijob, &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, &pl, &pr, 
		dif, &work[iwrk], &i__1, &iwork[1], liwork, &ierr);

	if (ijob >= 1) {
/* Computing MAX */
	    i__1 = maxwrk, i__2 = (*sdim << 1) * (*n - *sdim);
	    maxwrk = max(i__1,i__2);
	}
	if (ierr == -22) {

/*            not enough real workspace */

	    *info = -22;
	} else {
	    if (ijob == 1 || ijob == 4) {
		rconde[1] = pl;
		rconde[2] = pr;
	    }
	    if (ijob == 2 || ijob == 4) {
		rcondv[1] = dif[0];
		rcondv[2] = dif[1];
	    }
	    if (ierr == 1) {
		*info = *n + 3;
	    }
	}

    }

/*     Apply permutation to VSL and VSR   
       (Workspace: none needed) */

    if (ilvsl) {
	dggbak_("P", "L", n, &ilo, &ihi, &work[ileft], &work[iright], n, &vsl[
		vsl_offset], ldvsl, &ierr);
    }

    if (ilvsr) {
	dggbak_("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.) {
		if (alphar[i__] / safmax > anrmto / anrm || safmin / alphar[
			i__] > anrm / anrmto) {
		    work[1] = (d__1 = a[i__ + i__ * a_dim1] / alphar[i__], 
			    abs(d__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] = (d__1 = a[i__ + (i__ + 1) * a_dim1] / alphai[
			    i__], abs(d__1));
		    beta[i__] *= work[1];
		    alphar[i__] *= work[1];
		    alphai[i__] *= work[1];
		}
	    }
/* L20: */
	}
    }

    if (ilbscl) {
	i__1 = *n;
	for (i__ = 1; i__ <= i__1; ++i__) {
	    if (alphai[i__] != 0.) {
		if (beta[i__] / safmax > bnrmto / bnrm || safmin / beta[i__] 
			> bnrm / bnrmto) {
		    work[1] = (d__1 = b[i__ + i__ * b_dim1] / beta[i__], abs(
			    d__1));
		    beta[i__] *= work[1];
		    alphar[i__] *= work[1];
		    alphai[i__] *= work[1];
		}
	    }
/* L30: */
	}
    }

/*     Undo scaling */

    if (ilascl) {
	dlascl_("H", &c__0, &c__0, &anrmto, &anrm, n, n, &a[a_offset], lda, &
		ierr);
	dlascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphar[1], n, &
		ierr);
	dlascl_("G", &c__0, &c__0, &anrmto, &anrm, n, &c__1, &alphai[1], n, &
		ierr);
    }

    if (ilbscl) {
	dlascl_("U", &c__0, &c__0, &bnrmto, &bnrm, n, n, &b[b_offset], ldb, &
		ierr);
	dlascl_("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.) {
		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;
/* L50: */
	}

    }

L60:

    work[1] = (doublereal) maxwrk;
    iwork[1] = liwmin;

    return 0;

/*     End of DGGESX */

} /* dggesx_ */