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

/* Subroutine */ int zheevd_(char *jobz, char *uplo, integer *n, 
	doublecomplex *a, integer *lda, doublereal *w, doublecomplex *work, 
	integer *lwork, doublereal *rwork, integer *lrwork, integer *iwork, 
	integer *liwork, integer *info)
{
/*  -- LAPACK driver routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    ZHEEVD computes all eigenvalues and, optionally, eigenvectors of a   
    complex Hermitian matrix A.  If eigenvectors are desired, it uses a   
    divide and conquer algorithm.   

    The divide and conquer algorithm makes very mild assumptions about   
    floating point arithmetic. It will work on machines with a guard   
    digit in add/subtract, or on those binary machines without guard   
    digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or   
    Cray-2. It could conceivably fail on hexadecimal or decimal machines   
    without guard digits, but we know of none.   

    Arguments   
    =========   

    JOBZ    (input) CHARACTER*1   
            = 'N':  Compute eigenvalues only;   
            = 'V':  Compute eigenvalues and eigenvectors.   

    UPLO    (input) CHARACTER*1   
            = 'U':  Upper triangle of A is stored;   
            = 'L':  Lower triangle of A is stored.   

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

    A       (input/output) COMPLEX*16 array, dimension (LDA, N)   
            On entry, the Hermitian matrix A.  If UPLO = 'U', the   
            leading N-by-N upper triangular part of A contains the   
            upper triangular part of the matrix A.  If UPLO = 'L',   
            the leading N-by-N lower triangular part of A contains   
            the lower triangular part of the matrix A.   
            On exit, if JOBZ = 'V', then if INFO = 0, A contains the   
            orthonormal eigenvectors of the matrix A.   
            If JOBZ = 'N', then on exit the lower triangle (if UPLO='L')   
            or the upper triangle (if UPLO='U') of A, including the   
            diagonal, is destroyed.   

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

    W       (output) DOUBLE PRECISION array, dimension (N)   
            If INFO = 0, the eigenvalues in ascending order.   

    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 length of the array WORK.   
            If N <= 1,                LWORK must be at least 1.   
            If JOBZ  = 'N' and N > 1, LWORK must be at least N + 1.   
            If JOBZ  = 'V' and N > 1, LWORK must be at least 2*N + N**2.   

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

    RWORK   (workspace/output) DOUBLE PRECISION array,   
                                           dimension (LRWORK)   
            On exit, if INFO = 0, RWORK(1) returns the optimal LRWORK.   

    LRWORK  (input) INTEGER   
            The dimension of the array RWORK.   
            If N <= 1,                LRWORK must be at least 1.   
            If JOBZ  = 'N' and N > 1, LRWORK must be at least N.   
            If JOBZ  = 'V' and N > 1, LRWORK must be at least   
                           1 + 5*N + 2*N**2.   

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

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

    LIWORK  (input) INTEGER   
            The dimension of the array IWORK.   
            If N <= 1,                LIWORK must be at least 1.   
            If JOBZ  = 'N' and N > 1, LIWORK must be at least 1.   
            If JOBZ  = 'V' and N > 1, LIWORK must be at least 3 + 5*N.   

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

    INFO    (output) INTEGER   
            = 0:  successful exit   
            < 0:  if INFO = -i, the i-th argument had an illegal value   
            > 0:  if INFO = i and JOBZ = 'N', then the algorithm failed   
                  to converge; i off-diagonal elements of an intermediate   
                  tridiagonal form did not converge to zero;   
                  if INFO = i and JOBZ = 'V', then the algorithm failed   
                  to compute an eigenvalue while working on the submatrix   
                  lying in rows and columns INFO/(N+1) through   
                  mod(INFO,N+1).   

    Further Details   
    ===============   

    Based on contributions by   
       Jeff Rutter, Computer Science Division, University of California   
       at Berkeley, USA   

    Modified description of INFO. Sven, 16 Feb 05.   
    =====================================================================   


       Test the input parameters.   

       Parameter adjustments */
    /* Table of constant values */
    static integer c__1 = 1;
    static integer c_n1 = -1;
    static integer c__0 = 0;
    static doublereal c_b18 = 1.;
    
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2;
    doublereal d__1;
    /* Builtin functions */
    double sqrt(doublereal);
    /* Local variables */
    static doublereal eps;
    static integer inde;
    static doublereal anrm;
    static integer imax;
    static doublereal rmin, rmax;
    static integer lopt;
    extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *, 
	    integer *);
    static doublereal sigma;
    extern logical lsame_(char *, char *);
    static integer iinfo, lwmin, liopt;
    static logical lower;
    static integer llrwk, lropt;
    static logical wantz;
    static integer indwk2, llwrk2;
    extern doublereal dlamch_(char *);
    static integer iscale;
    static doublereal safmin;
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
	    integer *, integer *, ftnlen, ftnlen);
    extern /* Subroutine */ int xerbla_(char *, integer *);
    static doublereal bignum;
    extern doublereal zlanhe_(char *, char *, integer *, doublecomplex *, 
	    integer *, doublereal *);
    static integer indtau;
    extern /* Subroutine */ int dsterf_(integer *, doublereal *, doublereal *,
	     integer *), zlascl_(char *, integer *, integer *, doublereal *, 
	    doublereal *, integer *, integer *, doublecomplex *, integer *, 
	    integer *), zstedc_(char *, integer *, doublereal *, 
	    doublereal *, doublecomplex *, integer *, doublecomplex *, 
	    integer *, doublereal *, integer *, integer *, integer *, integer 
	    *);
    static integer indrwk, indwrk, liwmin;
    extern /* Subroutine */ int zhetrd_(char *, integer *, doublecomplex *, 
	    integer *, doublereal *, doublereal *, doublecomplex *, 
	    doublecomplex *, integer *, integer *), zlacpy_(char *, 
	    integer *, integer *, doublecomplex *, integer *, doublecomplex *,
	     integer *);
    static integer lrwmin, llwork;
    static doublereal smlnum;
    static logical lquery;
    extern /* Subroutine */ int zunmtr_(char *, char *, char *, integer *, 
	    integer *, doublecomplex *, integer *, doublecomplex *, 
	    doublecomplex *, integer *, doublecomplex *, integer *, integer *);


    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --w;
    --work;
    --rwork;
    --iwork;

    /* Function Body */
    wantz = lsame_(jobz, "V");
    lower = lsame_(uplo, "L");
    lquery = *lwork == -1 || *lrwork == -1 || *liwork == -1;

    *info = 0;
    if (! (wantz || lsame_(jobz, "N"))) {
	*info = -1;
    } else if (! (lower || lsame_(uplo, "U"))) {
	*info = -2;
    } else if (*n < 0) {
	*info = -3;
    } else if (*lda < max(1,*n)) {
	*info = -5;
    }

    if (*info == 0) {
	if (*n <= 1) {
	    lwmin = 1;
	    lrwmin = 1;
	    liwmin = 1;
	    lopt = lwmin;
	    lropt = lrwmin;
	    liopt = liwmin;
	} else {
	    if (wantz) {
		lwmin = (*n << 1) + *n * *n;
/* Computing 2nd power */
		i__1 = *n;
		lrwmin = *n * 5 + 1 + (i__1 * i__1 << 1);
		liwmin = *n * 5 + 3;
	    } else {
		lwmin = *n + 1;
		lrwmin = *n;
		liwmin = 1;
	    }
/* Computing MAX */
	    i__1 = lwmin, i__2 = *n + ilaenv_(&c__1, "ZHETRD", uplo, n, &c_n1,
		     &c_n1, &c_n1, (ftnlen)6, (ftnlen)1);
	    lopt = max(i__1,i__2);
	    lropt = lrwmin;
	    liopt = liwmin;
	}
	work[1].r = (doublereal) lopt, work[1].i = 0.;
	rwork[1] = (doublereal) lropt;
	iwork[1] = liopt;

	if (*lwork < lwmin && ! lquery) {
	    *info = -8;
	} else if (*lrwork < lrwmin && ! lquery) {
	    *info = -10;
	} else if (*liwork < liwmin && ! lquery) {
	    *info = -12;
	}
    }

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

/*     Quick return if possible */

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

    if (*n == 1) {
	i__1 = a_dim1 + 1;
	w[1] = a[i__1].r;
	if (wantz) {
	    i__1 = a_dim1 + 1;
	    a[i__1].r = 1., a[i__1].i = 0.;
	}
	return 0;
    }

/*     Get machine constants. */

    safmin = dlamch_("Safe minimum");
    eps = dlamch_("Precision");
    smlnum = safmin / eps;
    bignum = 1. / smlnum;
    rmin = sqrt(smlnum);
    rmax = sqrt(bignum);

/*     Scale matrix to allowable range, if necessary. */

    anrm = zlanhe_("M", uplo, n, &a[a_offset], lda, &rwork[1]);
    iscale = 0;
    if (anrm > 0. && anrm < rmin) {
	iscale = 1;
	sigma = rmin / anrm;
    } else if (anrm > rmax) {
	iscale = 1;
	sigma = rmax / anrm;
    }
    if (iscale == 1) {
	zlascl_(uplo, &c__0, &c__0, &c_b18, &sigma, n, n, &a[a_offset], lda, 
		info);
    }

/*     Call ZHETRD to reduce Hermitian matrix to tridiagonal form. */

    inde = 1;
    indtau = 1;
    indwrk = indtau + *n;
    indrwk = inde + *n;
    indwk2 = indwrk + *n * *n;
    llwork = *lwork - indwrk + 1;
    llwrk2 = *lwork - indwk2 + 1;
    llrwk = *lrwork - indrwk + 1;
    zhetrd_(uplo, n, &a[a_offset], lda, &w[1], &rwork[inde], &work[indtau], &
	    work[indwrk], &llwork, &iinfo);

/*     For eigenvalues only, call DSTERF.  For eigenvectors, first call   
       ZSTEDC to generate the eigenvector matrix, WORK(INDWRK), of the   
       tridiagonal matrix, then call ZUNMTR to multiply it to the   
       Householder transformations represented as Householder vectors in   
       A. */

    if (! wantz) {
	dsterf_(n, &w[1], &rwork[inde], info);
    } else {
	zstedc_("I", n, &w[1], &rwork[inde], &work[indwrk], n, &work[indwk2], 
		&llwrk2, &rwork[indrwk], &llrwk, &iwork[1], liwork, info);
	zunmtr_("L", uplo, "N", n, n, &a[a_offset], lda, &work[indtau], &work[
		indwrk], n, &work[indwk2], &llwrk2, &iinfo);
	zlacpy_("A", n, n, &work[indwrk], n, &a[a_offset], lda);
    }

/*     If matrix was scaled, then rescale eigenvalues appropriately. */

    if (iscale == 1) {
	if (*info == 0) {
	    imax = *n;
	} else {
	    imax = *info - 1;
	}
	d__1 = 1. / sigma;
	dscal_(&imax, &d__1, &w[1], &c__1);
    }

    work[1].r = (doublereal) lopt, work[1].i = 0.;
    rwork[1] = (doublereal) lropt;
    iwork[1] = liopt;

    return 0;

/*     End of ZHEEVD */

} /* zheevd_ */