423 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			423 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
#include "clapack.h"
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/* Table of constant values */
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static integer c__9 = 9;
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static integer c__0 = 0;
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static integer c__2 = 2;
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static real c_b23 = 1.f;
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static real c_b24 = 0.f;
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static integer c__1 = 1;
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/* Subroutine */ int slaed0_(integer *icompq, integer *qsiz, integer *n, real 
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	*d__, real *e, real *q, integer *ldq, real *qstore, integer *ldqs, 
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	real *work, integer *iwork, integer *info)
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{
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    /* System generated locals */
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    integer q_dim1, q_offset, qstore_dim1, qstore_offset, i__1, i__2;
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    real r__1;
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    /* Builtin functions */
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    double log(doublereal);
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    integer pow_ii(integer *, integer *);
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    /* Local variables */
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    integer i__, j, k, iq, lgn, msd2, smm1, spm1, spm2;
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    real temp;
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    integer curr;
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    extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, 
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	    integer *, real *, real *, integer *, real *, integer *, real *, 
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	    real *, integer *);
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    integer iperm, indxq, iwrem;
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    extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, 
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	    integer *);
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    integer iqptr, tlvls;
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    extern /* Subroutine */ int slaed1_(integer *, real *, real *, integer *, 
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	    integer *, real *, integer *, real *, integer *, integer *), 
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	    slaed7_(integer *, integer *, integer *, integer *, integer *, 
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	    integer *, real *, real *, integer *, integer *, real *, integer *
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, real *, integer *, integer *, integer *, integer *, integer *, 
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	    real *, real *, integer *, integer *);
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    integer igivcl;
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    extern /* Subroutine */ int xerbla_(char *, integer *);
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    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
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	    integer *, integer *);
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    integer igivnm, submat;
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    extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *, 
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	    integer *, real *, integer *);
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    integer curprb, subpbs, igivpt, curlvl, matsiz, iprmpt, smlsiz;
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    extern /* Subroutine */ int ssteqr_(char *, integer *, real *, real *, 
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	    real *, integer *, real *, integer *);
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/*  -- LAPACK routine (version 3.1) -- */
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/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
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/*     November 2006 */
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/*     .. Scalar Arguments .. */
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/*     .. */
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/*     .. Array Arguments .. */
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/*     .. */
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/*  Purpose */
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/*  ======= */
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/*  SLAED0 computes all eigenvalues and corresponding eigenvectors of a */
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/*  symmetric tridiagonal matrix using the divide and conquer method. */
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/*  Arguments */
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/*  ========= */
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/*  ICOMPQ  (input) INTEGER */
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/*          = 0:  Compute eigenvalues only. */
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/*          = 1:  Compute eigenvectors of original dense symmetric matrix */
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/*                also.  On entry, Q contains the orthogonal matrix used */
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/*                to reduce the original matrix to tridiagonal form. */
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/*          = 2:  Compute eigenvalues and eigenvectors of tridiagonal */
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/*                matrix. */
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/*  QSIZ   (input) INTEGER */
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/*         The dimension of the orthogonal matrix used to reduce */
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/*         the full matrix to tridiagonal form.  QSIZ >= N if ICOMPQ = 1. */
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/*  N      (input) INTEGER */
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/*         The dimension of the symmetric tridiagonal matrix.  N >= 0. */
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/*  D      (input/output) REAL array, dimension (N) */
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/*         On entry, the main diagonal of the tridiagonal matrix. */
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/*         On exit, its eigenvalues. */
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/*  E      (input) REAL array, dimension (N-1) */
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/*         The off-diagonal elements of the tridiagonal matrix. */
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/*         On exit, E has been destroyed. */
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/*  Q      (input/output) REAL array, dimension (LDQ, N) */
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/*         On entry, Q must contain an N-by-N orthogonal matrix. */
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/*         If ICOMPQ = 0    Q is not referenced. */
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/*         If ICOMPQ = 1    On entry, Q is a subset of the columns of the */
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/*                          orthogonal matrix used to reduce the full */
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/*                          matrix to tridiagonal form corresponding to */
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/*                          the subset of the full matrix which is being */
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/*                          decomposed at this time. */
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/*         If ICOMPQ = 2    On entry, Q will be the identity matrix. */
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/*                          On exit, Q contains the eigenvectors of the */
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/*                          tridiagonal matrix. */
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/*  LDQ    (input) INTEGER */
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/*         The leading dimension of the array Q.  If eigenvectors are */
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/*         desired, then  LDQ >= max(1,N).  In any case,  LDQ >= 1. */
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/*  QSTORE (workspace) REAL array, dimension (LDQS, N) */
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/*         Referenced only when ICOMPQ = 1.  Used to store parts of */
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/*         the eigenvector matrix when the updating matrix multiplies */
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/*         take place. */
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/*  LDQS   (input) INTEGER */
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/*         The leading dimension of the array QSTORE.  If ICOMPQ = 1, */
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/*         then  LDQS >= max(1,N).  In any case,  LDQS >= 1. */
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/*  WORK   (workspace) REAL array, */
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/*         If ICOMPQ = 0 or 1, the dimension of WORK must be at least */
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/*                     1 + 3*N + 2*N*lg N + 2*N**2 */
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/*                     ( lg( N ) = smallest integer k */
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/*                                 such that 2^k >= N ) */
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/*         If ICOMPQ = 2, the dimension of WORK must be at least */
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/*                     4*N + N**2. */
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/*  IWORK  (workspace) INTEGER array, */
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/*         If ICOMPQ = 0 or 1, the dimension of IWORK must be at least */
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/*                        6 + 6*N + 5*N*lg N. */
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/*                        ( lg( N ) = smallest integer k */
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/*                                    such that 2^k >= N ) */
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/*         If ICOMPQ = 2, the dimension of IWORK must be at least */
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/*                        3 + 5*N. */
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/*  INFO   (output) INTEGER */
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/*          = 0:  successful exit. */
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/*          < 0:  if INFO = -i, the i-th argument had an illegal value. */
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/*          > 0:  The algorithm failed to compute an eigenvalue while */
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/*                working on the submatrix lying in rows and columns */
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/*                INFO/(N+1) through mod(INFO,N+1). */
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/*  Further Details */
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/*  =============== */
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/*  Based on contributions by */
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/*     Jeff Rutter, Computer Science Division, University of California */
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/*     at Berkeley, USA */
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/*  ===================================================================== */
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/*     .. Parameters .. */
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/*     .. */
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/*     .. Local Scalars .. */
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/*     .. */
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/*     .. External Subroutines .. */
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/*     .. */
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/*     .. External Functions .. */
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/*     .. */
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/*     .. Intrinsic Functions .. */
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/*     .. */
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/*     .. Executable Statements .. */
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/*     Test the input parameters. */
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    /* Parameter adjustments */
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    --d__;
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    --e;
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    q_dim1 = *ldq;
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    q_offset = 1 + q_dim1;
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    q -= q_offset;
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    qstore_dim1 = *ldqs;
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    qstore_offset = 1 + qstore_dim1;
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    qstore -= qstore_offset;
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    --work;
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    --iwork;
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    /* Function Body */
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    *info = 0;
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    if (*icompq < 0 || *icompq > 2) {
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	*info = -1;
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    } else if (*icompq == 1 && *qsiz < max(0,*n)) {
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	*info = -2;
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    } else if (*n < 0) {
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	*info = -3;
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    } else if (*ldq < max(1,*n)) {
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	*info = -7;
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    } else if (*ldqs < max(1,*n)) {
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	*info = -9;
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    }
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    if (*info != 0) {
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	i__1 = -(*info);
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	xerbla_("SLAED0", &i__1);
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	return 0;
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    }
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/*     Quick return if possible */
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    if (*n == 0) {
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	return 0;
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    }
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    smlsiz = ilaenv_(&c__9, "SLAED0", " ", &c__0, &c__0, &c__0, &c__0);
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/*     Determine the size and placement of the submatrices, and save in */
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/*     the leading elements of IWORK. */
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    iwork[1] = *n;
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    subpbs = 1;
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    tlvls = 0;
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L10:
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    if (iwork[subpbs] > smlsiz) {
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	for (j = subpbs; j >= 1; --j) {
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	    iwork[j * 2] = (iwork[j] + 1) / 2;
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	    iwork[(j << 1) - 1] = iwork[j] / 2;
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/* L20: */
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	}
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	++tlvls;
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	subpbs <<= 1;
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	goto L10;
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    }
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    i__1 = subpbs;
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    for (j = 2; j <= i__1; ++j) {
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	iwork[j] += iwork[j - 1];
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/* L30: */
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    }
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/*     Divide the matrix into SUBPBS submatrices of size at most SMLSIZ+1 */
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/*     using rank-1 modifications (cuts). */
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    spm1 = subpbs - 1;
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    i__1 = spm1;
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    for (i__ = 1; i__ <= i__1; ++i__) {
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	submat = iwork[i__] + 1;
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	smm1 = submat - 1;
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	d__[smm1] -= (r__1 = e[smm1], dabs(r__1));
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	d__[submat] -= (r__1 = e[smm1], dabs(r__1));
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/* L40: */
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    }
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    indxq = (*n << 2) + 3;
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    if (*icompq != 2) {
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/*        Set up workspaces for eigenvalues only/accumulate new vectors */
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/*        routine */
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	temp = log((real) (*n)) / log(2.f);
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	lgn = (integer) temp;
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	if (pow_ii(&c__2, &lgn) < *n) {
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	    ++lgn;
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	}
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	if (pow_ii(&c__2, &lgn) < *n) {
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	    ++lgn;
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	}
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	iprmpt = indxq + *n + 1;
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	iperm = iprmpt + *n * lgn;
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	iqptr = iperm + *n * lgn;
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	igivpt = iqptr + *n + 2;
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	igivcl = igivpt + *n * lgn;
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	igivnm = 1;
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	iq = igivnm + (*n << 1) * lgn;
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/* Computing 2nd power */
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	i__1 = *n;
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	iwrem = iq + i__1 * i__1 + 1;
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/*        Initialize pointers */
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	i__1 = subpbs;
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	for (i__ = 0; i__ <= i__1; ++i__) {
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	    iwork[iprmpt + i__] = 1;
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	    iwork[igivpt + i__] = 1;
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/* L50: */
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	}
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	iwork[iqptr] = 1;
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    }
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/*     Solve each submatrix eigenproblem at the bottom of the divide and */
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/*     conquer tree. */
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    curr = 0;
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    i__1 = spm1;
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    for (i__ = 0; i__ <= i__1; ++i__) {
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	if (i__ == 0) {
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	    submat = 1;
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	    matsiz = iwork[1];
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	} else {
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	    submat = iwork[i__] + 1;
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	    matsiz = iwork[i__ + 1] - iwork[i__];
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	}
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	if (*icompq == 2) {
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	    ssteqr_("I", &matsiz, &d__[submat], &e[submat], &q[submat + 
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		    submat * q_dim1], ldq, &work[1], info);
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	    if (*info != 0) {
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		goto L130;
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	    }
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	} else {
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	    ssteqr_("I", &matsiz, &d__[submat], &e[submat], &work[iq - 1 + 
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		    iwork[iqptr + curr]], &matsiz, &work[1], info);
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	    if (*info != 0) {
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		goto L130;
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	    }
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	    if (*icompq == 1) {
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		sgemm_("N", "N", qsiz, &matsiz, &matsiz, &c_b23, &q[submat * 
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			q_dim1 + 1], ldq, &work[iq - 1 + iwork[iqptr + curr]], 
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			 &matsiz, &c_b24, &qstore[submat * qstore_dim1 + 1], 
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			ldqs);
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	    }
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/* Computing 2nd power */
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	    i__2 = matsiz;
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	    iwork[iqptr + curr + 1] = iwork[iqptr + curr] + i__2 * i__2;
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	    ++curr;
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	}
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	k = 1;
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	i__2 = iwork[i__ + 1];
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	for (j = submat; j <= i__2; ++j) {
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	    iwork[indxq + j] = k;
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	    ++k;
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/* L60: */
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	}
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/* L70: */
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    }
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/*     Successively merge eigensystems of adjacent submatrices */
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/*     into eigensystem for the corresponding larger matrix. */
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/*     while ( SUBPBS > 1 ) */
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    curlvl = 1;
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L80:
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    if (subpbs > 1) {
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	spm2 = subpbs - 2;
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	i__1 = spm2;
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	for (i__ = 0; i__ <= i__1; i__ += 2) {
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	    if (i__ == 0) {
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		submat = 1;
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		matsiz = iwork[2];
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		msd2 = iwork[1];
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		curprb = 0;
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	    } else {
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		submat = iwork[i__] + 1;
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		matsiz = iwork[i__ + 2] - iwork[i__];
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		msd2 = matsiz / 2;
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		++curprb;
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	    }
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/*     Merge lower order eigensystems (of size MSD2 and MATSIZ - MSD2) */
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/*     into an eigensystem of size MATSIZ. */
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/*     SLAED1 is used only for the full eigensystem of a tridiagonal */
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/*     matrix. */
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/*     SLAED7 handles the cases in which eigenvalues only or eigenvalues */
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/*     and eigenvectors of a full symmetric matrix (which was reduced to */
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/*     tridiagonal form) are desired. */
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	    if (*icompq == 2) {
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		slaed1_(&matsiz, &d__[submat], &q[submat + submat * q_dim1], 
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			ldq, &iwork[indxq + submat], &e[submat + msd2 - 1], &
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			msd2, &work[1], &iwork[subpbs + 1], info);
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	    } else {
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		slaed7_(icompq, &matsiz, qsiz, &tlvls, &curlvl, &curprb, &d__[
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			submat], &qstore[submat * qstore_dim1 + 1], ldqs, &
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			iwork[indxq + submat], &e[submat + msd2 - 1], &msd2, &
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			work[iq], &iwork[iqptr], &iwork[iprmpt], &iwork[iperm]
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, &iwork[igivpt], &iwork[igivcl], &work[igivnm], &
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			work[iwrem], &iwork[subpbs + 1], info);
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	    }
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	    if (*info != 0) {
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		goto L130;
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	    }
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	    iwork[i__ / 2 + 1] = iwork[i__ + 2];
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/* L90: */
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	}
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	subpbs /= 2;
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	++curlvl;
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	goto L80;
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    }
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/*     end while */
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/*     Re-merge the eigenvalues/vectors which were deflated at the final */
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/*     merge step. */
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    if (*icompq == 1) {
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	i__1 = *n;
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	for (i__ = 1; i__ <= i__1; ++i__) {
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	    j = iwork[indxq + i__];
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	    work[i__] = d__[j];
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	    scopy_(qsiz, &qstore[j * qstore_dim1 + 1], &c__1, &q[i__ * q_dim1 
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		    + 1], &c__1);
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/* L100: */
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	}
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	scopy_(n, &work[1], &c__1, &d__[1], &c__1);
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    } else if (*icompq == 2) {
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	i__1 = *n;
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	for (i__ = 1; i__ <= i__1; ++i__) {
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	    j = iwork[indxq + i__];
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	    work[i__] = d__[j];
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	    scopy_(n, &q[j * q_dim1 + 1], &c__1, &work[*n * i__ + 1], &c__1);
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/* L110: */
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	}
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	scopy_(n, &work[1], &c__1, &d__[1], &c__1);
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	slacpy_("A", n, n, &work[*n + 1], n, &q[q_offset], ldq);
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    } else {
 | 
						|
	i__1 = *n;
 | 
						|
	for (i__ = 1; i__ <= i__1; ++i__) {
 | 
						|
	    j = iwork[indxq + i__];
 | 
						|
	    work[i__] = d__[j];
 | 
						|
/* L120: */
 | 
						|
	}
 | 
						|
	scopy_(n, &work[1], &c__1, &d__[1], &c__1);
 | 
						|
    }
 | 
						|
    goto L140;
 | 
						|
 | 
						|
L130:
 | 
						|
    *info = submat * (*n + 1) + submat + matsiz - 1;
 | 
						|
 | 
						|
L140:
 | 
						|
    return 0;
 | 
						|
 | 
						|
/*     End of SLAED0 */
 | 
						|
 | 
						|
} /* slaed0_ */
 |