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version 1.8, 2011/07/22 07:38:05 version 1.9, 2011/11/21 20:42:53
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   *> \brief \b DGTCON
   *
   *  =========== DOCUMENTATION ===========
   *
   * Online html documentation available at 
   *            http://www.netlib.org/lapack/explore-html/ 
   *
   *> \htmlonly
   *> Download DGTCON + dependencies 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgtcon.f"> 
   *> [TGZ]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgtcon.f"> 
   *> [ZIP]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgtcon.f"> 
   *> [TXT]</a>
   *> \endhtmlonly 
   *
   *  Definition:
   *  ===========
   *
   *       SUBROUTINE DGTCON( NORM, N, DL, D, DU, DU2, IPIV, ANORM, RCOND,
   *                          WORK, IWORK, INFO )
   * 
   *       .. Scalar Arguments ..
   *       CHARACTER          NORM
   *       INTEGER            INFO, N
   *       DOUBLE PRECISION   ANORM, RCOND
   *       ..
   *       .. Array Arguments ..
   *       INTEGER            IPIV( * ), IWORK( * )
   *       DOUBLE PRECISION   D( * ), DL( * ), DU( * ), DU2( * ), WORK( * )
   *       ..
   *  
   *
   *> \par Purpose:
   *  =============
   *>
   *> \verbatim
   *>
   *> DGTCON estimates the reciprocal of the condition number of a real
   *> tridiagonal matrix A using the LU factorization as computed by
   *> DGTTRF.
   *>
   *> An estimate is obtained for norm(inv(A)), and the reciprocal of the
   *> condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
   *> \endverbatim
   *
   *  Arguments:
   *  ==========
   *
   *> \param[in] NORM
   *> \verbatim
   *>          NORM is CHARACTER*1
   *>          Specifies whether the 1-norm condition number or the
   *>          infinity-norm condition number is required:
   *>          = '1' or 'O':  1-norm;
   *>          = 'I':         Infinity-norm.
   *> \endverbatim
   *>
   *> \param[in] N
   *> \verbatim
   *>          N is INTEGER
   *>          The order of the matrix A.  N >= 0.
   *> \endverbatim
   *>
   *> \param[in] DL
   *> \verbatim
   *>          DL is DOUBLE PRECISION array, dimension (N-1)
   *>          The (n-1) multipliers that define the matrix L from the
   *>          LU factorization of A as computed by DGTTRF.
   *> \endverbatim
   *>
   *> \param[in] D
   *> \verbatim
   *>          D is DOUBLE PRECISION array, dimension (N)
   *>          The n diagonal elements of the upper triangular matrix U from
   *>          the LU factorization of A.
   *> \endverbatim
   *>
   *> \param[in] DU
   *> \verbatim
   *>          DU is DOUBLE PRECISION array, dimension (N-1)
   *>          The (n-1) elements of the first superdiagonal of U.
   *> \endverbatim
   *>
   *> \param[in] DU2
   *> \verbatim
   *>          DU2 is DOUBLE PRECISION array, dimension (N-2)
   *>          The (n-2) elements of the second superdiagonal of U.
   *> \endverbatim
   *>
   *> \param[in] IPIV
   *> \verbatim
   *>          IPIV is INTEGER array, dimension (N)
   *>          The pivot indices; for 1 <= i <= n, row i of the matrix was
   *>          interchanged with row IPIV(i).  IPIV(i) will always be either
   *>          i or i+1; IPIV(i) = i indicates a row interchange was not
   *>          required.
   *> \endverbatim
   *>
   *> \param[in] ANORM
   *> \verbatim
   *>          ANORM is DOUBLE PRECISION
   *>          If NORM = '1' or 'O', the 1-norm of the original matrix A.
   *>          If NORM = 'I', the infinity-norm of the original matrix A.
   *> \endverbatim
   *>
   *> \param[out] RCOND
   *> \verbatim
   *>          RCOND is DOUBLE PRECISION
   *>          The reciprocal of the condition number of the matrix A,
   *>          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
   *>          estimate of the 1-norm of inv(A) computed in this routine.
   *> \endverbatim
   *>
   *> \param[out] WORK
   *> \verbatim
   *>          WORK is DOUBLE PRECISION array, dimension (2*N)
   *> \endverbatim
   *>
   *> \param[out] IWORK
   *> \verbatim
   *>          IWORK is INTEGER array, dimension (N)
   *> \endverbatim
   *>
   *> \param[out] INFO
   *> \verbatim
   *>          INFO is INTEGER
   *>          = 0:  successful exit
   *>          < 0:  if INFO = -i, the i-th argument had an illegal value
   *> \endverbatim
   *
   *  Authors:
   *  ========
   *
   *> \author Univ. of Tennessee 
   *> \author Univ. of California Berkeley 
   *> \author Univ. of Colorado Denver 
   *> \author NAG Ltd. 
   *
   *> \date November 2011
   *
   *> \ingroup doubleOTHERcomputational
   *
   *  =====================================================================
       SUBROUTINE DGTCON( NORM, N, DL, D, DU, DU2, IPIV, ANORM, RCOND,        SUBROUTINE DGTCON( NORM, N, DL, D, DU, DU2, IPIV, ANORM, RCOND,
      $                   WORK, IWORK, INFO )       $                   WORK, IWORK, INFO )
 *  *
 *  -- LAPACK routine (version 3.3.1) --  *  -- LAPACK computational routine (version 3.4.0) --
 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --  *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--  *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
 *  -- April 2011                                                      --  *     November 2011
 *  
 *     Modified to call DLACN2 in place of DLACON, 5 Feb 03, SJH.  
 *  *
 *     .. Scalar Arguments ..  *     .. Scalar Arguments ..
       CHARACTER          NORM        CHARACTER          NORM
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       DOUBLE PRECISION   D( * ), DL( * ), DU( * ), DU2( * ), WORK( * )        DOUBLE PRECISION   D( * ), DL( * ), DU( * ), DU2( * ), WORK( * )
 *     ..  *     ..
 *  *
 *  Purpose  
 *  =======  
 *  
 *  DGTCON estimates the reciprocal of the condition number of a real  
 *  tridiagonal matrix A using the LU factorization as computed by  
 *  DGTTRF.  
 *  
 *  An estimate is obtained for norm(inv(A)), and the reciprocal of the  
 *  condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).  
 *  
 *  Arguments  
 *  =========  
 *  
 *  NORM    (input) CHARACTER*1  
 *          Specifies whether the 1-norm condition number or the  
 *          infinity-norm condition number is required:  
 *          = '1' or 'O':  1-norm;  
 *          = 'I':         Infinity-norm.  
 *  
 *  N       (input) INTEGER  
 *          The order of the matrix A.  N >= 0.  
 *  
 *  DL      (input) DOUBLE PRECISION array, dimension (N-1)  
 *          The (n-1) multipliers that define the matrix L from the  
 *          LU factorization of A as computed by DGTTRF.  
 *  
 *  D       (input) DOUBLE PRECISION array, dimension (N)  
 *          The n diagonal elements of the upper triangular matrix U from  
 *          the LU factorization of A.  
 *  
 *  DU      (input) DOUBLE PRECISION array, dimension (N-1)  
 *          The (n-1) elements of the first superdiagonal of U.  
 *  
 *  DU2     (input) DOUBLE PRECISION array, dimension (N-2)  
 *          The (n-2) elements of the second superdiagonal of U.  
 *  
 *  IPIV    (input) INTEGER array, dimension (N)  
 *          The pivot indices; for 1 <= i <= n, row i of the matrix was  
 *          interchanged with row IPIV(i).  IPIV(i) will always be either  
 *          i or i+1; IPIV(i) = i indicates a row interchange was not  
 *          required.  
 *  
 *  ANORM   (input) DOUBLE PRECISION  
 *          If NORM = '1' or 'O', the 1-norm of the original matrix A.  
 *          If NORM = 'I', the infinity-norm of the original matrix A.  
 *  
 *  RCOND   (output) DOUBLE PRECISION  
 *          The reciprocal of the condition number of the matrix A,  
 *          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an  
 *          estimate of the 1-norm of inv(A) computed in this routine.  
 *  
 *  WORK    (workspace) DOUBLE PRECISION array, dimension (2*N)  
 *  
 *  IWORK   (workspace) INTEGER array, dimension (N)  
 *  
 *  INFO    (output) INTEGER  
 *          = 0:  successful exit  
 *          < 0:  if INFO = -i, the i-th argument had an illegal value  
 *  
 *  =====================================================================  *  =====================================================================
 *  *
 *     .. Parameters ..  *     .. Parameters ..
Removed from v.1.8  
changed lines
  Added in v.1.9

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