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

/* Subroutine */ int claed0_(integer *qsiz, integer *n, real *d__, real *e, 
	complex *q, integer *ldq, complex *qstore, integer *ldqs, real *rwork,
	 integer *iwork, integer *info)
{
/*  -- LAPACK routine (version 3.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       September 30, 1994   


    Purpose   
    =======   

    Using the divide and conquer method, CLAED0 computes all eigenvalues   
    of a symmetric tridiagonal matrix which is one diagonal block of   
    those from reducing a dense or band Hermitian matrix and   
    corresponding eigenvectors of the dense or band matrix.   

    Arguments   
    =========   

    QSIZ   (input) INTEGER   
           The dimension of the unitary matrix used to reduce   
           the full matrix to tridiagonal form.  QSIZ >= N if ICOMPQ = 1.   

    N      (input) INTEGER   
           The dimension of the symmetric tridiagonal matrix.  N >= 0.   

    D      (input/output) REAL array, dimension (N)   
           On entry, the diagonal elements of the tridiagonal matrix.   
           On exit, the eigenvalues in ascending order.   

    E      (input/output) REAL array, dimension (N-1)   
           On entry, the off-diagonal elements of the tridiagonal matrix.   
           On exit, E has been destroyed.   

    Q      (input/output) COMPLEX array, dimension (LDQ,N)   
           On entry, Q must contain an QSIZ x N matrix whose columns   
           unitarily orthonormal. It is a part of the unitary matrix   
           that reduces the full dense Hermitian matrix to a   
           (reducible) symmetric tridiagonal matrix.   

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

    IWORK  (workspace) INTEGER array,   
           the dimension of IWORK must be at least   
                        6 + 6*N + 5*N*lg N   
                        ( lg( N ) = smallest integer k   
                                    such that 2^k >= N )   

    RWORK  (workspace) REAL array,   
                                 dimension (1 + 3*N + 2*N*lg N + 3*N**2)   
                          ( lg( N ) = smallest integer k   
                                      such that 2^k >= N )   

    QSTORE (workspace) COMPLEX array, dimension (LDQS, N)   
           Used to store parts of   
           the eigenvector matrix when the updating matrix multiplies   
           take place.   

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

    INFO   (output) INTEGER   
            = 0:  successful exit.   
            < 0:  if INFO = -i, the i-th argument had an illegal value.   
            > 0:  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).   

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

    Warning:      N could be as big as QSIZ!   


       Test the input parameters.   

       Parameter adjustments */
    /* Table of constant values */
    static integer c__9 = 9;
    static integer c__0 = 0;
    static integer c__2 = 2;
    static integer c__1 = 1;
    
    /* System generated locals */
    integer q_dim1, q_offset, qstore_dim1, qstore_offset, i__1, i__2;
    real r__1;
    /* Builtin functions */
    double log(doublereal);
    integer pow_ii(integer *, integer *);
    /* Local variables */
    static real temp;
    static integer curr, i__, j, k, iperm;
    extern /* Subroutine */ int ccopy_(integer *, complex *, integer *, 
	    complex *, integer *);
    static integer indxq, iwrem;
    extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, 
	    integer *);
    static integer iqptr;
    extern /* Subroutine */ int claed7_(integer *, integer *, integer *, 
	    integer *, integer *, integer *, real *, complex *, integer *, 
	    real *, integer *, real *, integer *, integer *, integer *, 
	    integer *, integer *, real *, complex *, real *, integer *, 
	    integer *);
    static integer tlvls, ll, iq;
    extern /* Subroutine */ int clacrm_(integer *, integer *, complex *, 
	    integer *, real *, integer *, complex *, integer *, real *);
    static integer igivcl;
    extern /* Subroutine */ int xerbla_(char *, integer *);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
	    integer *, integer *, ftnlen, ftnlen);
    static integer igivnm, submat, curprb, subpbs, igivpt, curlvl, matsiz, 
	    iprmpt, smlsiz;
    extern /* Subroutine */ int ssteqr_(char *, integer *, real *, real *, 
	    real *, integer *, real *, integer *);
    static integer lgn, msd2, smm1, spm1, spm2;
#define q_subscr(a_1,a_2) (a_2)*q_dim1 + a_1
#define q_ref(a_1,a_2) q[q_subscr(a_1,a_2)]
#define qstore_subscr(a_1,a_2) (a_2)*qstore_dim1 + a_1
#define qstore_ref(a_1,a_2) qstore[qstore_subscr(a_1,a_2)]


    --d__;
    --e;
    q_dim1 = *ldq;
    q_offset = 1 + q_dim1 * 1;
    q -= q_offset;
    qstore_dim1 = *ldqs;
    qstore_offset = 1 + qstore_dim1 * 1;
    qstore -= qstore_offset;
    --rwork;
    --iwork;

    /* Function Body */
    *info = 0;

/*     IF( ICOMPQ .LT. 0 .OR. ICOMPQ .GT. 2 ) THEN   
          INFO = -1   
       ELSE IF( ( ICOMPQ .EQ. 1 ) .AND. ( QSIZ .LT. MAX( 0, N ) ) )   
      $        THEN */
    if (*qsiz < max(0,*n)) {
	*info = -1;
    } else if (*n < 0) {
	*info = -2;
    } else if (*ldq < max(1,*n)) {
	*info = -6;
    } else if (*ldqs < max(1,*n)) {
	*info = -8;
    }
    if (*info != 0) {
	i__1 = -(*info);
	xerbla_("CLAED0", &i__1);
	return 0;
    }

/*     Quick return if possible */

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

    smlsiz = ilaenv_(&c__9, "CLAED0", " ", &c__0, &c__0, &c__0, &c__0, (
	    ftnlen)6, (ftnlen)1);

/*     Determine the size and placement of the submatrices, and save in   
       the leading elements of IWORK. */

    iwork[1] = *n;
    subpbs = 1;
    tlvls = 0;
L10:
    if (iwork[subpbs] > smlsiz) {
	for (j = subpbs; j >= 1; --j) {
	    iwork[j * 2] = (iwork[j] + 1) / 2;
	    iwork[(j << 1) - 1] = iwork[j] / 2;
/* L20: */
	}
	++tlvls;
	subpbs <<= 1;
	goto L10;
    }
    i__1 = subpbs;
    for (j = 2; j <= i__1; ++j) {
	iwork[j] += iwork[j - 1];
/* L30: */
    }

/*     Divide the matrix into SUBPBS submatrices of size at most SMLSIZ+1   
       using rank-1 modifications (cuts). */

    spm1 = subpbs - 1;
    i__1 = spm1;
    for (i__ = 1; i__ <= i__1; ++i__) {
	submat = iwork[i__] + 1;
	smm1 = submat - 1;
	d__[smm1] -= (r__1 = e[smm1], dabs(r__1));
	d__[submat] -= (r__1 = e[smm1], dabs(r__1));
/* L40: */
    }

    indxq = (*n << 2) + 3;

/*     Set up workspaces for eigenvalues only/accumulate new vectors   
       routine */

    temp = log((real) (*n)) / log(2.f);
    lgn = (integer) temp;
    if (pow_ii(&c__2, &lgn) < *n) {
	++lgn;
    }
    if (pow_ii(&c__2, &lgn) < *n) {
	++lgn;
    }
    iprmpt = indxq + *n + 1;
    iperm = iprmpt + *n * lgn;
    iqptr = iperm + *n * lgn;
    igivpt = iqptr + *n + 2;
    igivcl = igivpt + *n * lgn;

    igivnm = 1;
    iq = igivnm + (*n << 1) * lgn;
/* Computing 2nd power */
    i__1 = *n;
    iwrem = iq + i__1 * i__1 + 1;
/*     Initialize pointers */
    i__1 = subpbs;
    for (i__ = 0; i__ <= i__1; ++i__) {
	iwork[iprmpt + i__] = 1;
	iwork[igivpt + i__] = 1;
/* L50: */
    }
    iwork[iqptr] = 1;

/*     Solve each submatrix eigenproblem at the bottom of the divide and   
       conquer tree. */

    curr = 0;
    i__1 = spm1;
    for (i__ = 0; i__ <= i__1; ++i__) {
	if (i__ == 0) {
	    submat = 1;
	    matsiz = iwork[1];
	} else {
	    submat = iwork[i__] + 1;
	    matsiz = iwork[i__ + 1] - iwork[i__];
	}
	ll = iq - 1 + iwork[iqptr + curr];
	ssteqr_("I", &matsiz, &d__[submat], &e[submat], &rwork[ll], &matsiz, &
		rwork[1], info);
	clacrm_(qsiz, &matsiz, &q_ref(1, submat), ldq, &rwork[ll], &matsiz, &
		qstore_ref(1, submat), ldqs, &rwork[iwrem]);
/* Computing 2nd power */
	i__2 = matsiz;
	iwork[iqptr + curr + 1] = iwork[iqptr + curr] + i__2 * i__2;
	++curr;
	if (*info > 0) {
	    *info = submat * (*n + 1) + submat + matsiz - 1;
	    return 0;
	}
	k = 1;
	i__2 = iwork[i__ + 1];
	for (j = submat; j <= i__2; ++j) {
	    iwork[indxq + j] = k;
	    ++k;
/* L60: */
	}
/* L70: */
    }

/*     Successively merge eigensystems of adjacent submatrices   
       into eigensystem for the corresponding larger matrix.   

       while ( SUBPBS > 1 ) */

    curlvl = 1;
L80:
    if (subpbs > 1) {
	spm2 = subpbs - 2;
	i__1 = spm2;
	for (i__ = 0; i__ <= i__1; i__ += 2) {
	    if (i__ == 0) {
		submat = 1;
		matsiz = iwork[2];
		msd2 = iwork[1];
		curprb = 0;
	    } else {
		submat = iwork[i__] + 1;
		matsiz = iwork[i__ + 2] - iwork[i__];
		msd2 = matsiz / 2;
		++curprb;
	    }

/*     Merge lower order eigensystems (of size MSD2 and MATSIZ - MSD2)   
       into an eigensystem of size MATSIZ.  CLAED7 handles the case   
       when the eigenvectors of a full or band Hermitian matrix (which   
       was reduced to tridiagonal form) are desired.   

       I am free to use Q as a valuable working space until Loop 150. */

	    claed7_(&matsiz, &msd2, qsiz, &tlvls, &curlvl, &curprb, &d__[
		    submat], &qstore_ref(1, submat), ldqs, &e[submat + msd2 - 
		    1], &iwork[indxq + submat], &rwork[iq], &iwork[iqptr], &
		    iwork[iprmpt], &iwork[iperm], &iwork[igivpt], &iwork[
		    igivcl], &rwork[igivnm], &q_ref(1, submat), &rwork[iwrem],
		     &iwork[subpbs + 1], info);
	    if (*info > 0) {
		*info = submat * (*n + 1) + submat + matsiz - 1;
		return 0;
	    }
	    iwork[i__ / 2 + 1] = iwork[i__ + 2];
/* L90: */
	}
	subpbs /= 2;
	++curlvl;
	goto L80;
    }

/*     end while   

       Re-merge the eigenvalues/vectors which were deflated at the final   
       merge step. */

    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
	j = iwork[indxq + i__];
	rwork[i__] = d__[j];
	ccopy_(qsiz, &qstore_ref(1, j), &c__1, &q_ref(1, i__), &c__1);
/* L100: */
    }
    scopy_(n, &rwork[1], &c__1, &d__[1], &c__1);

    return 0;

/*     End of CLAED0 */

} /* claed0_ */

#undef qstore_ref
#undef qstore_subscr
#undef q_ref
#undef q_subscr


