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    1:       SUBROUTINE DSYTRI2( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )
    2: *
    3: *  -- LAPACK routine (version 3.3.1) --
    4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
    5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
    6: *  -- April 2011                                                      --
    7: *
    8: *  -- Written by Julie Langou of the Univ. of TN    --
    9: *
   10: * @generated d
   11: *     .. Scalar Arguments ..
   12:       CHARACTER          UPLO
   13:       INTEGER            INFO, LDA, LWORK, N
   14: *     ..
   15: *     .. Array Arguments ..
   16:       INTEGER            IPIV( * )
   17:       DOUBLE PRECISION   A( LDA, * ), WORK( * )
   18: *     ..
   19: *
   20: *  Purpose
   21: *  =======
   22: *
   23: *  DSYTRI2 computes the inverse of a DOUBLE PRECISION hermitian indefinite matrix
   24: *  A using the factorization A = U*D*U**T or A = L*D*L**T computed by
   25: *  DSYTRF. DSYTRI2 sets the LEADING DIMENSION of the workspace
   26: *  before calling DSYTRI2X that actually computes the inverse.
   27: *
   28: *  Arguments
   29: *  =========
   30: *
   31: *  UPLO    (input) CHARACTER*1
   32: *          Specifies whether the details of the factorization are stored
   33: *          as an upper or lower triangular matrix.
   34: *          = 'U':  Upper triangular, form is A = U*D*U**T;
   35: *          = 'L':  Lower triangular, form is A = L*D*L**T.
   36: *
   37: *  N       (input) INTEGER
   38: *          The order of the matrix A.  N >= 0.
   39: *
   40: *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
   41: *          On entry, the NB diagonal matrix D and the multipliers
   42: *          used to obtain the factor U or L as computed by DSYTRF.
   43: *
   44: *          On exit, if INFO = 0, the (symmetric) inverse of the original
   45: *          matrix.  If UPLO = 'U', the upper triangular part of the
   46: *          inverse is formed and the part of A below the diagonal is not
   47: *          referenced; if UPLO = 'L' the lower triangular part of the
   48: *          inverse is formed and the part of A above the diagonal is
   49: *          not referenced.
   50: *
   51: *  LDA     (input) INTEGER
   52: *          The leading dimension of the array A.  LDA >= max(1,N).
   53: *
   54: *  IPIV    (input) INTEGER array, dimension (N)
   55: *          Details of the interchanges and the NB structure of D
   56: *          as determined by DSYTRF.
   57: *
   58: *  WORK    (workspace) DOUBLE PRECISION array, dimension (N+NB+1)*(NB+3)
   59: *
   60: *  LWORK   (input) INTEGER
   61: *          The dimension of the array WORK.
   62: *          WORK is size >= (N+NB+1)*(NB+3)
   63: *          If LDWORK = -1, then a workspace query is assumed; the routine
   64: *           calculates:
   65: *              - the optimal size of the WORK array, returns
   66: *          this value as the first entry of the WORK array,
   67: *              - and no error message related to LDWORK is issued by XERBLA.
   68: *
   69: *  INFO    (output) INTEGER
   70: *          = 0: successful exit
   71: *          < 0: if INFO = -i, the i-th argument had an illegal value
   72: *          > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
   73: *               inverse could not be computed.
   74: *
   75: *  =====================================================================
   76: *
   77: *     .. Local Scalars ..
   78:       LOGICAL            UPPER, LQUERY
   79:       INTEGER            MINSIZE, NBMAX
   80: *     ..
   81: *     .. External Functions ..
   82:       LOGICAL            LSAME
   83:       INTEGER            ILAENV
   84:       EXTERNAL           LSAME, ILAENV
   85: *     ..
   86: *     .. External Subroutines ..
   87:       EXTERNAL           DSYTRI2X
   88: *     ..
   89: *     .. Executable Statements ..
   90: *
   91: *     Test the input parameters.
   92: *
   93:       INFO = 0
   94:       UPPER = LSAME( UPLO, 'U' )
   95:       LQUERY = ( LWORK.EQ.-1 )
   96: *     Get blocksize
   97:       NBMAX = ILAENV( 1, 'DSYTRF', UPLO, N, -1, -1, -1 )
   98:       IF ( NBMAX .GE. N ) THEN
   99:          MINSIZE = N
  100:       ELSE
  101:          MINSIZE = (N+NBMAX+1)*(NBMAX+3)
  102:       END IF
  103: *
  104:       IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
  105:          INFO = -1
  106:       ELSE IF( N.LT.0 ) THEN
  107:          INFO = -2
  108:       ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
  109:          INFO = -4
  110:       ELSE IF (LWORK .LT. MINSIZE .AND. .NOT.LQUERY ) THEN
  111:          INFO = -7
  112:       END IF
  113: *
  114: *     Quick return if possible
  115: *
  116: *
  117:       IF( INFO.NE.0 ) THEN
  118:          CALL XERBLA( 'DSYTRI2', -INFO )
  119:          RETURN
  120:       ELSE IF( LQUERY ) THEN
  121:          WORK(1)=MINSIZE
  122:          RETURN
  123:       END IF
  124:       IF( N.EQ.0 )
  125:      $   RETURN
  126:       
  127:       IF( NBMAX .GE. N ) THEN
  128:          CALL DSYTRI( UPLO, N, A, LDA, IPIV, WORK, INFO )
  129:       ELSE
  130:          CALL DSYTRI2X( UPLO, N, A, LDA, IPIV, WORK, NBMAX, INFO )
  131:       END IF
  132:       RETURN
  133: *
  134: *     End of DSYTRI2
  135: *
  136:       END