/* ../netlib/dlarrd.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_n1 = -1;
static integer c__3 = 3;
static integer c__2 = 2;
static integer c__0 = 0;
/* > \brief \b DLARRD computes the eigenvalues of a symmetric tridiagonal matrix to suitable accuracy. */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download DLARRD + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarrd. f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarrd. f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarrd. f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE DLARRD( RANGE, ORDER, N, VL, VU, IL, IU, GERS, */
/* RELTOL, D, E, E2, PIVMIN, NSPLIT, ISPLIT, */
/* M, W, WERR, WL, WU, IBLOCK, INDEXW, */
/* WORK, IWORK, INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER ORDER, RANGE */
/* INTEGER IL, INFO, IU, M, N, NSPLIT */
/* DOUBLE PRECISION PIVMIN, RELTOL, VL, VU, WL, WU */
/* .. */
/* .. Array Arguments .. */
/* INTEGER IBLOCK( * ), INDEXW( * ), */
/* $ ISPLIT( * ), IWORK( * ) */
/* DOUBLE PRECISION D( * ), E( * ), E2( * ), */
/* $ GERS( * ), W( * ), WERR( * ), WORK( * ) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > DLARRD computes the eigenvalues of a symmetric tridiagonal */
/* > matrix T to suitable accuracy. This is an auxiliary code to be */
/* > called from DSTEMR. */
/* > The user may ask for all eigenvalues, all eigenvalues */
/* > in the half-open interval (VL, VU], or the IL-th through IU-th */
/* > eigenvalues. */
/* > */
/* > To avoid overflow, the matrix must be scaled so that its */
/* > largest element is no greater than overflow**(1/2) * underflow**(1/4) in absolute value, and for greatest */
/* > accuracy, it should not be much smaller than that. */
/* > */
/* > See W. Kahan "Accurate Eigenvalues of a Symmetric Tridiagonal */
/* > Matrix", Report CS41, Computer Science Dept., Stanford */
/* > University, July 21, 1966. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] RANGE */
/* > \verbatim */
/* > RANGE is CHARACTER*1 */
/* > = 'A': ("All") all eigenvalues will be found. */
/* > = 'V': ("Value") all eigenvalues in the half-open interval */
/* > (VL, VU] will be found. */
/* > = 'I': ("Index") the IL-th through IU-th eigenvalues (of the */
/* > entire matrix) will be found. */
/* > \endverbatim */
/* > */
/* > \param[in] ORDER */
/* > \verbatim */
/* > ORDER is CHARACTER*1 */
/* > = 'B': ("By Block") the eigenvalues will be grouped by */
/* > split-off block (see IBLOCK, ISPLIT) and */
/* > ordered from smallest to largest within */
/* > the block. */
/* > = 'E': ("Entire matrix") */
/* > the eigenvalues for the entire matrix */
/* > will be ordered from smallest to */
/* > largest. */
/* > \endverbatim */
/* > */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > The order of the tridiagonal matrix T. N >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in] VL */
/* > \verbatim */
/* > VL is DOUBLE PRECISION */
/* > \endverbatim */
/* > */
/* > \param[in] VU */
/* > \verbatim */
/* > VU is DOUBLE PRECISION */
/* > If RANGE='V', the lower and upper bounds of the interval to */
/* > be searched for eigenvalues. Eigenvalues less than or equal */
/* > to VL, or greater than VU, will not be returned. VL < VU. */
/* > Not referenced if RANGE = 'A' or 'I'. */
/* > \endverbatim */
/* > */
/* > \param[in] IL */
/* > \verbatim */
/* > IL is INTEGER */
/* > \endverbatim */
/* > */
/* > \param[in] IU */
/* > \verbatim */
/* > IU is INTEGER */
/* > If RANGE='I', the indices (in ascending order) of the */
/* > smallest and largest eigenvalues to be returned. */
/* > 1 <= IL <= IU <= N, if N > 0;
IL = 1 and IU = 0 if N = 0. */
/* > Not referenced if RANGE = 'A' or 'V'. */
/* > \endverbatim */
/* > */
/* > \param[in] GERS */
/* > \verbatim */
/* > GERS is DOUBLE PRECISION array, dimension (2*N) */
/* > The N Gerschgorin intervals (the i-th Gerschgorin interval */
/* > is (GERS(2*i-1), GERS(2*i)). */
/* > \endverbatim */
/* > */
/* > \param[in] RELTOL */
/* > \verbatim */
/* > RELTOL is DOUBLE PRECISION */
/* > The minimum relative width of an interval. When an interval */
/* > is narrower than RELTOL times the larger (in */
/* > magnitude) endpoint, then it is considered to be */
/* > sufficiently small, i.e., converged. Note: this should */
/* > always be at least radix*machine epsilon. */
/* > \endverbatim */
/* > */
/* > \param[in] D */
/* > \verbatim */
/* > D is DOUBLE PRECISION array, dimension (N) */
/* > The n diagonal elements of the tridiagonal matrix T. */
/* > \endverbatim */
/* > */
/* > \param[in] E */
/* > \verbatim */
/* > E is DOUBLE PRECISION array, dimension (N-1) */
/* > The (n-1) off-diagonal elements of the tridiagonal matrix T. */
/* > \endverbatim */
/* > */
/* > \param[in] E2 */
/* > \verbatim */
/* > E2 is DOUBLE PRECISION array, dimension (N-1) */
/* > The (n-1) squared off-diagonal elements of the tridiagonal matrix T. */
/* > \endverbatim */
/* > */
/* > \param[in] PIVMIN */
/* > \verbatim */
/* > PIVMIN is DOUBLE PRECISION */
/* > The minimum pivot allowed in the Sturm sequence for T. */
/* > \endverbatim */
/* > */
/* > \param[in] NSPLIT */
/* > \verbatim */
/* > NSPLIT is INTEGER */
/* > The number of diagonal blocks in the matrix T. */
/* > 1 <= NSPLIT <= N. */
/* > \endverbatim */
/* > */
/* > \param[in] ISPLIT */
/* > \verbatim */
/* > ISPLIT is INTEGER array, dimension (N) */
/* > The splitting points, at which T breaks up into submatrices. */
/* > The first submatrix consists of rows/columns 1 to ISPLIT(1), */
/* > the second of rows/columns ISPLIT(1)+1 through ISPLIT(2), */
/* > etc., and the NSPLIT-th consists of rows/columns */
/* > ISPLIT(NSPLIT-1)+1 through ISPLIT(NSPLIT)=N. */
/* > (Only the first NSPLIT elements will actually be used, but */
/* > since the user cannot know a priori what value NSPLIT will */
/* > have, N words must be reserved for ISPLIT.) */
/* > \endverbatim */
/* > */
/* > \param[out] M */
/* > \verbatim */
/* > M is INTEGER */
/* > The actual number of eigenvalues found. 0 <= M <= N. */
/* > (See also the description of INFO=2,3.) */
/* > \endverbatim */
/* > */
/* > \param[out] W */
/* > \verbatim */
/* > W is DOUBLE PRECISION array, dimension (N) */
/* > On exit, the first M elements of W will contain the */
/* > eigenvalue approximations. DLARRD computes an interval */
/* > I_j = (a_j, b_j] that includes eigenvalue j. The eigenvalue */
/* > approximation is given as the interval midpoint */
/* > W(j)= ( a_j + b_j)/2. The corresponding error is bounded by */
/* > WERR(j) = f2c_abs( a_j - b_j)/2 */
/* > \endverbatim */
/* > */
/* > \param[out] WERR */
/* > \verbatim */
/* > WERR is DOUBLE PRECISION array, dimension (N) */
/* > The error bound on the corresponding eigenvalue approximation */
/* > in W. */
/* > \endverbatim */
/* > */
/* > \param[out] WL */
/* > \verbatim */
/* > WL is DOUBLE PRECISION */
/* > \endverbatim */
/* > */
/* > \param[out] WU */
/* > \verbatim */
/* > WU is DOUBLE PRECISION */
/* > The interval (WL, WU] contains all the wanted eigenvalues. */
/* > If RANGE='V', then WL=VL and WU=VU. */
/* > If RANGE='A', then WL and WU are the global Gerschgorin bounds */
/* > on the spectrum. */
/* > If RANGE='I', then WL and WU are computed by DLAEBZ from the */
/* > index range specified. */
/* > \endverbatim */
/* > */
/* > \param[out] IBLOCK */
/* > \verbatim */
/* > IBLOCK is INTEGER array, dimension (N) */
/* > At each row/column j where E(j) is zero or small, the */
/* > matrix T is considered to split into a block diagonal */
/* > matrix. On exit, if INFO = 0, IBLOCK(i) specifies to which */
/* > block (from 1 to the number of blocks) the eigenvalue W(i) */
/* > belongs. (DLARRD may use the remaining N-M elements as */
/* > workspace.) */
/* > \endverbatim */
/* > */
/* > \param[out] INDEXW */
/* > \verbatim */
/* > INDEXW is INTEGER array, dimension (N) */
/* > The indices of the eigenvalues within each block (submatrix);
*/
/* > for example, INDEXW(i)= j and IBLOCK(i)=k imply that the */
/* > i-th eigenvalue W(i) is the j-th eigenvalue in block k. */
/* > \endverbatim */
/* > */
/* > \param[out] WORK */
/* > \verbatim */
/* > WORK is DOUBLE PRECISION array, dimension (4*N) */
/* > \endverbatim */
/* > */
/* > \param[out] IWORK */
/* > \verbatim */
/* > IWORK is INTEGER array, dimension (3*N) */
/* > \endverbatim */
/* > */
/* > \param[out] INFO */
/* > \verbatim */
/* > INFO is INTEGER */
/* > = 0: successful exit */
/* > < 0: if INFO = -i, the i-th argument had an illegal value */
/* > > 0: some or all of the eigenvalues failed to converge or */
/* > were not computed: */
/* > =1 or 3: Bisection failed to converge for some */
/* > eigenvalues;
these eigenvalues are flagged by a */
/* > negative block number. The effect is that the */
/* > eigenvalues may not be as accurate as the */
/* > absolute and relative tolerances. This is */
/* > generally caused by unexpectedly inaccurate */
/* > arithmetic. */
/* > =2 or 3: RANGE='I' only: Not all of the eigenvalues */
/* > IL:IU were found. */
/* > Effect: M < IU+1-IL */
/* > Cause: non-monotonic arithmetic, causing the */
/* > Sturm sequence to be non-monotonic. */
/* > Cure: recalculate, using RANGE='A', and pick */
/* > out eigenvalues IL:IU. In some cases, */
/* > increasing the PARAMETER "FUDGE" may */
/* > make things work. */
/* > = 4: RANGE='I', and the Gershgorin interval */
/* > initially used was too small. No eigenvalues */
/* > were computed. */
/* > Probable cause: your machine has sloppy */
/* > floating-point arithmetic. */
/* > Cure: Increase the PARAMETER "FUDGE", */
/* > recompile, and try again. */
/* > \endverbatim */
/* > \par Internal Parameters: */
/* ========================= */
/* > */
/* > \verbatim */
/* > FUDGE DOUBLE PRECISION, default = 2 */
/* > A "fudge factor" to widen the Gershgorin intervals. Ideally, */
/* > a value of 1 should work, but on machines with sloppy */
/* > arithmetic, this needs to be larger. The default for */
/* > publicly released versions should be large enough to handle */
/* > the worst machine around. Note that this has no effect */
/* > on accuracy of the solution. */
/* > \endverbatim */
/* > */
/* > \par Contributors: */
/* ================== */
/* > */
/* > W. Kahan, University of California, Berkeley, USA \n */
/* > Beresford Parlett, University of California, Berkeley, USA \n */
/* > Jim Demmel, University of California, Berkeley, USA \n */
/* > Inderjit Dhillon, University of Texas, Austin, USA \n */
/* > Osni Marques, LBNL/NERSC, USA \n */
/* > Christof Voemel, University of California, Berkeley, USA \n */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \date September 2012 */
/* > \ingroup auxOTHERauxiliary */
/* ===================================================================== */
/* Subroutine */
int dlarrd_(char *range, char *order, integer *n, doublereal *vl, doublereal *vu, integer *il, integer *iu, doublereal *gers, doublereal *reltol, doublereal *d__, doublereal *e, doublereal *e2, doublereal *pivmin, integer *nsplit, integer *isplit, integer *m, doublereal *w, doublereal *werr, doublereal *wl, doublereal *wu, integer *iblock, integer *indexw, doublereal *work, integer *iwork, integer *info)
{
    /* System generated locals */
    integer i__1, i__2, i__3;
    doublereal d__1, d__2;
    /* Builtin functions */
    double log(doublereal);
    /* Local variables */
    integer i__, j, ib, ie, je, nb;
    doublereal gl;
    integer im, in;
    doublereal gu;
    integer iw, jee;
    doublereal eps;
    integer nwl;
    doublereal wlu, wul;
    integer nwu;
    doublereal tmp1, tmp2;
    integer iend, jblk, ioff, iout, itmp1, itmp2, jdisc;
    extern logical lsame_(char *, char *);
    integer iinfo;
    doublereal atoli;
    integer iwoff, itmax;
    doublereal wkill, rtoli, uflow, tnorm;
    extern doublereal dlamch_(char *);
    integer ibegin;
    extern /* Subroutine */
    int dlaebz_(integer *, integer *, integer *, integer *, integer *, integer *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, integer *, doublereal *, doublereal *, integer *, integer *, doublereal *, integer *, integer *);
    integer irange, idiscl, idumma[1];
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *);
    integer idiscu;
    logical ncnvrg, toofew;
    /* -- LAPACK auxiliary routine (version 3.4.2) -- */
    /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
    /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
    /* September 2012 */
    /* .. Scalar Arguments .. */
    /* .. */
    /* .. Array Arguments .. */
    /* .. */
    /* ===================================================================== */
    /* .. Parameters .. */
    /* .. */
    /* .. Local Scalars .. */
    /* .. */
    /* .. Local Arrays .. */
    /* .. */
    /* .. External Functions .. */
    /* .. */
    /* .. External Subroutines .. */
    /* .. */
    /* .. Intrinsic Functions .. */
    /* .. */
    /* .. Executable Statements .. */
    /* Parameter adjustments */
    --iwork;
    --work;
    --indexw;
    --iblock;
    --werr;
    --w;
    --isplit;
    --e2;
    --e;
    --d__;
    --gers;
    /* Function Body */
    *info = 0;
    /* Decode RANGE */
    if (lsame_(range, "A"))
    {
        irange = 1;
    }
    else if (lsame_(range, "V"))
    {
        irange = 2;
    }
    else if (lsame_(range, "I"))
    {
        irange = 3;
    }
    else
    {
        irange = 0;
    }
    /* Check for Errors */
    if (irange <= 0)
    {
        *info = -1;
    }
    else if (! (lsame_(order, "B") || lsame_(order, "E")))
    {
        *info = -2;
    }
    else if (*n < 0)
    {
        *info = -3;
    }
    else if (irange == 2)
    {
        if (*vl >= *vu)
        {
            *info = -5;
        }
    }
    else if (irange == 3 && (*il < 1 || *il > max(1,*n)))
    {
        *info = -6;
    }
    else if (irange == 3 && (*iu < min(*n,*il) || *iu > *n))
    {
        *info = -7;
    }
    if (*info != 0)
    {
        return 0;
    }
    /* Initialize error flags */
    *info = 0;
    ncnvrg = FALSE_;
    toofew = FALSE_;
    /* Quick return if possible */
    *m = 0;
    if (*n == 0)
    {
        return 0;
    }
    /* Simplification: */
    if (irange == 3 && *il == 1 && *iu == *n)
    {
        irange = 1;
    }
    /* Get machine constants */
    eps = dlamch_("P");
    uflow = dlamch_("U");
    /* Special Case when N=1 */
    /* Treat case of 1x1 matrix for quick return */
    if (*n == 1)
    {
        if (irange == 1 || irange == 2 && d__[1] > *vl && d__[1] <= *vu || irange == 3 && *il == 1 && *iu == 1)
        {
            *m = 1;
            w[1] = d__[1];
            /* The computation error of the eigenvalue is zero */
            werr[1] = 0.;
            iblock[1] = 1;
            indexw[1] = 1;
        }
        return 0;
    }
    /* NB is the minimum vector length for vector bisection, or 0 */
    /* if only scalar is to be done. */
    nb = ilaenv_(&c__1, "DSTEBZ", " ", n, &c_n1, &c_n1, &c_n1);
    if (nb <= 1)
    {
        nb = 0;
    }
    /* Find global spectral radius */
    gl = d__[1];
    gu = d__[1];
    i__1 = *n;
    for (i__ = 1;
            i__ <= i__1;
            ++i__)
    {
        /* Computing MIN */
        d__1 = gl;
        d__2 = gers[(i__ << 1) - 1]; // , expr subst
        gl = min(d__1,d__2);
        /* Computing MAX */
        d__1 = gu;
        d__2 = gers[i__ * 2]; // , expr subst
        gu = max(d__1,d__2);
        /* L5: */
    }
    /* Compute global Gerschgorin bounds and spectral diameter */
    /* Computing MAX */
    d__1 = f2c_abs(gl);
    d__2 = f2c_abs(gu); // , expr subst
    tnorm = max(d__1,d__2);
    gl = gl - tnorm * 2. * eps * *n - *pivmin * 4.;
    gu = gu + tnorm * 2. * eps * *n + *pivmin * 4.;
    /* [JAN/28/2009] remove the line below since SPDIAM variable not use */
    /* SPDIAM = GU - GL */
    /* Input arguments for DLAEBZ: */
    /* The relative tolerance. An interval (a,b] lies within */
    /* "relative tolerance" if b-a < RELTOL*max(|a|,|b|), */
    rtoli = *reltol;
    /* Set the absolute tolerance for interval convergence to zero to force */
    /* interval convergence based on relative size of the interval. */
    /* This is dangerous because intervals might not converge when RELTOL is */
    /* small. But at least a very small number should be selected so that for */
    /* strongly graded matrices, the code can get relatively accurate */
    /* eigenvalues. */
    atoli = uflow * 4. + *pivmin * 4.;
    if (irange == 3)
    {
        /* RANGE='I': Compute an interval containing eigenvalues */
        /* IL through IU. The initial interval [GL,GU] from the global */
        /* Gerschgorin bounds GL and GU is refined by DLAEBZ. */
        itmax = (integer) ((log(tnorm + *pivmin) - log(*pivmin)) / log(2.)) + 2;
        work[*n + 1] = gl;
        work[*n + 2] = gl;
        work[*n + 3] = gu;
        work[*n + 4] = gu;
        work[*n + 5] = gl;
        work[*n + 6] = gu;
        iwork[1] = -1;
        iwork[2] = -1;
        iwork[3] = *n + 1;
        iwork[4] = *n + 1;
        iwork[5] = *il - 1;
        iwork[6] = *iu;
        dlaebz_(&c__3, &itmax, n, &c__2, &c__2, &nb, &atoli, &rtoli, pivmin, & d__[1], &e[1], &e2[1], &iwork[5], &work[*n + 1], &work[*n + 5] , &iout, &iwork[1], &w[1], &iblock[1], &iinfo);
        if (iinfo != 0)
        {
            *info = iinfo;
            return 0;
        }
        /* On exit, output intervals may not be ordered by ascending negcount */
        if (iwork[6] == *iu)
        {
            *wl = work[*n + 1];
            wlu = work[*n + 3];
            nwl = iwork[1];
            *wu = work[*n + 4];
            wul = work[*n + 2];
            nwu = iwork[4];
        }
        else
        {
            *wl = work[*n + 2];
            wlu = work[*n + 4];
            nwl = iwork[2];
            *wu = work[*n + 3];
            wul = work[*n + 1];
            nwu = iwork[3];
        }
        /* On exit, the interval [WL, WLU] contains a value with negcount NWL, */
        /* and [WUL, WU] contains a value with negcount NWU. */
        if (nwl < 0 || nwl >= *n || nwu < 1 || nwu > *n)
        {
            *info = 4;
            return 0;
        }
    }
    else if (irange == 2)
    {
        *wl = *vl;
        *wu = *vu;
    }
    else if (irange == 1)
    {
        *wl = gl;
        *wu = gu;
    }
    /* Find Eigenvalues -- Loop Over blocks and recompute NWL and NWU. */
    /* NWL accumulates the number of eigenvalues .le. WL, */
    /* NWU accumulates the number of eigenvalues .le. WU */
    *m = 0;
    iend = 0;
    *info = 0;
    nwl = 0;
    nwu = 0;
    i__1 = *nsplit;
    for (jblk = 1;
            jblk <= i__1;
            ++jblk)
    {
        ioff = iend;
        ibegin = ioff + 1;
        iend = isplit[jblk];
        in = iend - ioff;
        if (in == 1)
        {
            /* 1x1 block */
            if (*wl >= d__[ibegin] - *pivmin)
            {
                ++nwl;
            }
            if (*wu >= d__[ibegin] - *pivmin)
            {
                ++nwu;
            }
            if (irange == 1 || *wl < d__[ibegin] - *pivmin && *wu >= d__[ ibegin] - *pivmin)
            {
                ++(*m);
                w[*m] = d__[ibegin];
                werr[*m] = 0.;
                /* The gap for a single block doesn't matter for the later */
                /* algorithm and is assigned an arbitrary large value */
                iblock[*m] = jblk;
                indexw[*m] = 1;
            }
            /* Disabled 2x2 case because of a failure on the following matrix */
            /* RANGE = 'I', IL = IU = 4 */
            /* Original Tridiagonal, d = [ */
            /* -0.150102010615740E+00 */
            /* -0.849897989384260E+00 */
            /* -0.128208148052635E-15 */
            /* 0.128257718286320E-15 */
            /* ];
            */
            /* e = [ */
            /* -0.357171383266986E+00 */
            /* -0.180411241501588E-15 */
            /* -0.175152352710251E-15 */
            /* ];
            */
            /* ELSE IF( IN.EQ.2 ) THEN */
            /* * 2x2 block */
            /* DISC = SQRT( (HALF*(D(IBEGIN)-D(IEND)))**2 + E(IBEGIN)**2 ) */
            /* TMP1 = HALF*(D(IBEGIN)+D(IEND)) */
            /* L1 = TMP1 - DISC */
            /* IF( WL.GE. L1-PIVMIN ) */
            /* $ NWL = NWL + 1 */
            /* IF( WU.GE. L1-PIVMIN ) */
            /* $ NWU = NWU + 1 */
            /* IF( IRANGE.EQ.ALLRNG .OR. ( WL.LT.L1-PIVMIN .AND. WU.GE. */
            /* $ L1-PIVMIN ) ) THEN */
            /* M = M + 1 */
            /* W( M ) = L1 */
            /* * The uncertainty of eigenvalues of a 2x2 matrix is very small */
            /* WERR( M ) = EPS * ABS( W( M ) ) * TWO */
            /* IBLOCK( M ) = JBLK */
            /* INDEXW( M ) = 1 */
            /* ENDIF */
            /* L2 = TMP1 + DISC */
            /* IF( WL.GE. L2-PIVMIN ) */
            /* $ NWL = NWL + 1 */
            /* IF( WU.GE. L2-PIVMIN ) */
            /* $ NWU = NWU + 1 */
            /* IF( IRANGE.EQ.ALLRNG .OR. ( WL.LT.L2-PIVMIN .AND. WU.GE. */
            /* $ L2-PIVMIN ) ) THEN */
            /* M = M + 1 */
            /* W( M ) = L2 */
            /* * The uncertainty of eigenvalues of a 2x2 matrix is very small */
            /* WERR( M ) = EPS * ABS( W( M ) ) * TWO */
            /* IBLOCK( M ) = JBLK */
            /* INDEXW( M ) = 2 */
            /* ENDIF */
        }
        else
        {
            /* General Case - block of size IN >= 2 */
            /* Compute local Gerschgorin interval and use it as the initial */
            /* interval for DLAEBZ */
            gu = d__[ibegin];
            gl = d__[ibegin];
            tmp1 = 0.;
            i__2 = iend;
            for (j = ibegin;
                    j <= i__2;
                    ++j)
            {
                /* Computing MIN */
                d__1 = gl;
                d__2 = gers[(j << 1) - 1]; // , expr subst
                gl = min(d__1,d__2);
                /* Computing MAX */
                d__1 = gu;
                d__2 = gers[j * 2]; // , expr subst
                gu = max(d__1,d__2);
                /* L40: */
            }
            /* [JAN/28/2009] */
            /* change SPDIAM by TNORM in lines 2 and 3 thereafter */
            /* line 1: remove computation of SPDIAM (not useful anymore) */
            /* SPDIAM = GU - GL */
            /* GL = GL - FUDGE*SPDIAM*EPS*IN - FUDGE*PIVMIN */
            /* GU = GU + FUDGE*SPDIAM*EPS*IN + FUDGE*PIVMIN */
            gl = gl - tnorm * 2. * eps * in - *pivmin * 2.;
            gu = gu + tnorm * 2. * eps * in + *pivmin * 2.;
            if (irange > 1)
            {
                if (gu < *wl)
                {
                    /* the local block contains none of the wanted eigenvalues */
                    nwl += in;
                    nwu += in;
                    goto L70;
                }
                /* refine search interval if possible, only range (WL,WU] matters */
                gl = max(gl,*wl);
                gu = min(gu,*wu);
                if (gl >= gu)
                {
                    goto L70;
                }
            }
            /* Find negcount of initial interval boundaries GL and GU */
            work[*n + 1] = gl;
            work[*n + in + 1] = gu;
            dlaebz_(&c__1, &c__0, &in, &in, &c__1, &nb, &atoli, &rtoli, pivmin, &d__[ibegin], &e[ibegin], &e2[ibegin], idumma, & work[*n + 1], &work[*n + (in << 1) + 1], &im, &iwork[1], & w[*m + 1], &iblock[*m + 1], &iinfo);
            if (iinfo != 0)
            {
                *info = iinfo;
                return 0;
            }
            nwl += iwork[1];
            nwu += iwork[in + 1];
            iwoff = *m - iwork[1];
            /* Compute Eigenvalues */
            itmax = (integer) ((log(gu - gl + *pivmin) - log(*pivmin)) / log( 2.)) + 2;
            dlaebz_(&c__2, &itmax, &in, &in, &c__1, &nb, &atoli, &rtoli, pivmin, &d__[ibegin], &e[ibegin], &e2[ibegin], idumma, & work[*n + 1], &work[*n + (in << 1) + 1], &iout, &iwork[1], &w[*m + 1], &iblock[*m + 1], &iinfo);
            if (iinfo != 0)
            {
                *info = iinfo;
                return 0;
            }
            /* Copy eigenvalues into W and IBLOCK */
            /* Use -JBLK for block number for unconverged eigenvalues. */
            /* Loop over the number of output intervals from DLAEBZ */
            i__2 = iout;
            for (j = 1;
                    j <= i__2;
                    ++j)
            {
                /* eigenvalue approximation is middle point of interval */
                tmp1 = (work[j + *n] + work[j + in + *n]) * .5;
                /* semi length of error interval */
                tmp2 = (d__1 = work[j + *n] - work[j + in + *n], f2c_abs(d__1)) * .5;
                if (j > iout - iinfo)
                {
                    /* Flag non-convergence. */
                    ncnvrg = TRUE_;
                    ib = -jblk;
                }
                else
                {
                    ib = jblk;
                }
                i__3 = iwork[j + in] + iwoff;
                for (je = iwork[j] + 1 + iwoff;
                        je <= i__3;
                        ++je)
                {
                    w[je] = tmp1;
                    werr[je] = tmp2;
                    indexw[je] = je - iwoff;
                    iblock[je] = ib;
                    /* L50: */
                }
                /* L60: */
            }
            *m += im;
        }
L70:
        ;
    }
    /* If RANGE='I', then (WL,WU) contains eigenvalues NWL+1,...,NWU */
    /* If NWL+1 < IL or NWU > IU, discard extra eigenvalues. */
    if (irange == 3)
    {
        idiscl = *il - 1 - nwl;
        idiscu = nwu - *iu;
        if (idiscl > 0)
        {
            im = 0;
            i__1 = *m;
            for (je = 1;
                    je <= i__1;
                    ++je)
            {
                /* Remove some of the smallest eigenvalues from the left so that */
                /* at the end IDISCL =0. Move all eigenvalues up to the left. */
                if (w[je] <= wlu && idiscl > 0)
                {
                    --idiscl;
                }
                else
                {
                    ++im;
                    w[im] = w[je];
                    werr[im] = werr[je];
                    indexw[im] = indexw[je];
                    iblock[im] = iblock[je];
                }
                /* L80: */
            }
            *m = im;
        }
        if (idiscu > 0)
        {
            /* Remove some of the largest eigenvalues from the right so that */
            /* at the end IDISCU =0. Move all eigenvalues up to the left. */
            im = *m + 1;
            for (je = *m;
                    je >= 1;
                    --je)
            {
                if (w[je] >= wul && idiscu > 0)
                {
                    --idiscu;
                }
                else
                {
                    --im;
                    w[im] = w[je];
                    werr[im] = werr[je];
                    indexw[im] = indexw[je];
                    iblock[im] = iblock[je];
                }
                /* L81: */
            }
            jee = 0;
            i__1 = *m;
            for (je = im;
                    je <= i__1;
                    ++je)
            {
                ++jee;
                w[jee] = w[je];
                werr[jee] = werr[je];
                indexw[jee] = indexw[je];
                iblock[jee] = iblock[je];
                /* L82: */
            }
            *m = *m - im + 1;
        }
        if (idiscl > 0 || idiscu > 0)
        {
            /* Code to deal with effects of bad arithmetic. (If N(w) is */
            /* monotone non-decreasing, this should never happen.) */
            /* Some low eigenvalues to be discarded are not in (WL,WLU], */
            /* or high eigenvalues to be discarded are not in (WUL,WU] */
            /* so just kill off the smallest IDISCL/largest IDISCU */
            /* eigenvalues, by marking the corresponding IBLOCK = 0 */
            if (idiscl > 0)
            {
                wkill = *wu;
                i__1 = idiscl;
                for (jdisc = 1;
                        jdisc <= i__1;
                        ++jdisc)
                {
                    iw = 0;
                    i__2 = *m;
                    for (je = 1;
                            je <= i__2;
                            ++je)
                    {
                        if (iblock[je] != 0 && (w[je] < wkill || iw == 0))
                        {
                            iw = je;
                            wkill = w[je];
                        }
                        /* L90: */
                    }
                    iblock[iw] = 0;
                    /* L100: */
                }
            }
            if (idiscu > 0)
            {
                wkill = *wl;
                i__1 = idiscu;
                for (jdisc = 1;
                        jdisc <= i__1;
                        ++jdisc)
                {
                    iw = 0;
                    i__2 = *m;
                    for (je = 1;
                            je <= i__2;
                            ++je)
                    {
                        if (iblock[je] != 0 && (w[je] >= wkill || iw == 0))
                        {
                            iw = je;
                            wkill = w[je];
                        }
                        /* L110: */
                    }
                    iblock[iw] = 0;
                    /* L120: */
                }
            }
            /* Now erase all eigenvalues with IBLOCK set to zero */
            im = 0;
            i__1 = *m;
            for (je = 1;
                    je <= i__1;
                    ++je)
            {
                if (iblock[je] != 0)
                {
                    ++im;
                    w[im] = w[je];
                    werr[im] = werr[je];
                    indexw[im] = indexw[je];
                    iblock[im] = iblock[je];
                }
                /* L130: */
            }
            *m = im;
        }
        if (idiscl < 0 || idiscu < 0)
        {
            toofew = TRUE_;
        }
    }
    if (irange == 1 && *m != *n || irange == 3 && *m != *iu - *il + 1)
    {
        toofew = TRUE_;
    }
    /* If ORDER='B', do nothing the eigenvalues are already sorted by */
    /* block. */
    /* If ORDER='E', sort the eigenvalues from smallest to largest */
    if (lsame_(order, "E") && *nsplit > 1)
    {
        i__1 = *m - 1;
        for (je = 1;
                je <= i__1;
                ++je)
        {
            ie = 0;
            tmp1 = w[je];
            i__2 = *m;
            for (j = je + 1;
                    j <= i__2;
                    ++j)
            {
                if (w[j] < tmp1)
                {
                    ie = j;
                    tmp1 = w[j];
                }
                /* L140: */
            }
            if (ie != 0)
            {
                tmp2 = werr[ie];
                itmp1 = iblock[ie];
                itmp2 = indexw[ie];
                w[ie] = w[je];
                werr[ie] = werr[je];
                iblock[ie] = iblock[je];
                indexw[ie] = indexw[je];
                w[je] = tmp1;
                werr[je] = tmp2;
                iblock[je] = itmp1;
                indexw[je] = itmp2;
            }
            /* L150: */
        }
    }
    *info = 0;
    if (ncnvrg)
    {
        ++(*info);
    }
    if (toofew)
    {
        *info += 2;
    }
    return 0;
    /* End of DLARRD */
}
/* dlarrd_ */