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version 1.7, 2010/12/21 13:53:55 version 1.8, 2011/11/21 20:43:21
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   *> \brief \b ZSTEQR
   *
   *  =========== DOCUMENTATION ===========
   *
   * Online html documentation available at 
   *            http://www.netlib.org/lapack/explore-html/ 
   *
   *> \htmlonly
   *> Download ZSTEQR + dependencies 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zsteqr.f"> 
   *> [TGZ]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zsteqr.f"> 
   *> [ZIP]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zsteqr.f"> 
   *> [TXT]</a>
   *> \endhtmlonly 
   *
   *  Definition:
   *  ===========
   *
   *       SUBROUTINE ZSTEQR( COMPZ, N, D, E, Z, LDZ, WORK, INFO )
   * 
   *       .. Scalar Arguments ..
   *       CHARACTER          COMPZ
   *       INTEGER            INFO, LDZ, N
   *       ..
   *       .. Array Arguments ..
   *       DOUBLE PRECISION   D( * ), E( * ), WORK( * )
   *       COMPLEX*16         Z( LDZ, * )
   *       ..
   *  
   *
   *> \par Purpose:
   *  =============
   *>
   *> \verbatim
   *>
   *> ZSTEQR computes all eigenvalues and, optionally, eigenvectors of a
   *> symmetric tridiagonal matrix using the implicit QL or QR method.
   *> The eigenvectors of a full or band complex Hermitian matrix can also
   *> be found if ZHETRD or ZHPTRD or ZHBTRD has been used to reduce this
   *> matrix to tridiagonal form.
   *> \endverbatim
   *
   *  Arguments:
   *  ==========
   *
   *> \param[in] COMPZ
   *> \verbatim
   *>          COMPZ is CHARACTER*1
   *>          = 'N':  Compute eigenvalues only.
   *>          = 'V':  Compute eigenvalues and eigenvectors of the original
   *>                  Hermitian matrix.  On entry, Z must contain the
   *>                  unitary matrix used to reduce the original matrix
   *>                  to tridiagonal form.
   *>          = 'I':  Compute eigenvalues and eigenvectors of the
   *>                  tridiagonal matrix.  Z is initialized to the identity
   *>                  matrix.
   *> \endverbatim
   *>
   *> \param[in] N
   *> \verbatim
   *>          N is INTEGER
   *>          The order of the matrix.  N >= 0.
   *> \endverbatim
   *>
   *> \param[in,out] D
   *> \verbatim
   *>          D is DOUBLE PRECISION array, dimension (N)
   *>          On entry, the diagonal elements of the tridiagonal matrix.
   *>          On exit, if INFO = 0, the eigenvalues in ascending order.
   *> \endverbatim
   *>
   *> \param[in,out] E
   *> \verbatim
   *>          E is DOUBLE PRECISION array, dimension (N-1)
   *>          On entry, the (n-1) subdiagonal elements of the tridiagonal
   *>          matrix.
   *>          On exit, E has been destroyed.
   *> \endverbatim
   *>
   *> \param[in,out] Z
   *> \verbatim
   *>          Z is COMPLEX*16 array, dimension (LDZ, N)
   *>          On entry, if  COMPZ = 'V', then Z contains the unitary
   *>          matrix used in the reduction to tridiagonal form.
   *>          On exit, if INFO = 0, then if COMPZ = 'V', Z contains the
   *>          orthonormal eigenvectors of the original Hermitian matrix,
   *>          and if COMPZ = 'I', Z contains the orthonormal eigenvectors
   *>          of the symmetric tridiagonal matrix.
   *>          If COMPZ = 'N', then Z is not referenced.
   *> \endverbatim
   *>
   *> \param[in] LDZ
   *> \verbatim
   *>          LDZ is INTEGER
   *>          The leading dimension of the array Z.  LDZ >= 1, and if
   *>          eigenvectors are desired, then  LDZ >= max(1,N).
   *> \endverbatim
   *>
   *> \param[out] WORK
   *> \verbatim
   *>          WORK is DOUBLE PRECISION array, dimension (max(1,2*N-2))
   *>          If COMPZ = 'N', then WORK is not referenced.
   *> \endverbatim
   *>
   *> \param[out] INFO
   *> \verbatim
   *>          INFO is INTEGER
   *>          = 0:  successful exit
   *>          < 0:  if INFO = -i, the i-th argument had an illegal value
   *>          > 0:  the algorithm has failed to find all the eigenvalues in
   *>                a total of 30*N iterations; if INFO = i, then i
   *>                elements of E have not converged to zero; on exit, D
   *>                and E contain the elements of a symmetric tridiagonal
   *>                matrix which is unitarily similar to the original
   *>                matrix.
   *> \endverbatim
   *
   *  Authors:
   *  ========
   *
   *> \author Univ. of Tennessee 
   *> \author Univ. of California Berkeley 
   *> \author Univ. of Colorado Denver 
   *> \author NAG Ltd. 
   *
   *> \date November 2011
   *
   *> \ingroup complex16OTHERcomputational
   *
   *  =====================================================================
       SUBROUTINE ZSTEQR( COMPZ, N, D, E, Z, LDZ, WORK, INFO )        SUBROUTINE ZSTEQR( COMPZ, N, D, E, Z, LDZ, WORK, INFO )
 *  *
 *  -- LAPACK routine (version 3.2) --  *  -- 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..--
 *     November 2006  *     November 2011
 *  *
 *     .. Scalar Arguments ..  *     .. Scalar Arguments ..
       CHARACTER          COMPZ        CHARACTER          COMPZ
Line 14 Line 146
       COMPLEX*16         Z( LDZ, * )        COMPLEX*16         Z( LDZ, * )
 *     ..  *     ..
 *  *
 *  Purpose  
 *  =======  
 *  
 *  ZSTEQR computes all eigenvalues and, optionally, eigenvectors of a  
 *  symmetric tridiagonal matrix using the implicit QL or QR method.  
 *  The eigenvectors of a full or band complex Hermitian matrix can also  
 *  be found if ZHETRD or ZHPTRD or ZHBTRD has been used to reduce this  
 *  matrix to tridiagonal form.  
 *  
 *  Arguments  
 *  =========  
 *  
 *  COMPZ   (input) CHARACTER*1  
 *          = 'N':  Compute eigenvalues only.  
 *          = 'V':  Compute eigenvalues and eigenvectors of the original  
 *                  Hermitian matrix.  On entry, Z must contain the  
 *                  unitary matrix used to reduce the original matrix  
 *                  to tridiagonal form.  
 *          = 'I':  Compute eigenvalues and eigenvectors of the  
 *                  tridiagonal matrix.  Z is initialized to the identity  
 *                  matrix.  
 *  
 *  N       (input) INTEGER  
 *          The order of the matrix.  N >= 0.  
 *  
 *  D       (input/output) DOUBLE PRECISION array, dimension (N)  
 *          On entry, the diagonal elements of the tridiagonal matrix.  
 *          On exit, if INFO = 0, the eigenvalues in ascending order.  
 *  
 *  E       (input/output) DOUBLE PRECISION array, dimension (N-1)  
 *          On entry, the (n-1) subdiagonal elements of the tridiagonal  
 *          matrix.  
 *          On exit, E has been destroyed.  
 *  
 *  Z       (input/output) COMPLEX*16 array, dimension (LDZ, N)  
 *          On entry, if  COMPZ = 'V', then Z contains the unitary  
 *          matrix used in the reduction to tridiagonal form.  
 *          On exit, if INFO = 0, then if COMPZ = 'V', Z contains the  
 *          orthonormal eigenvectors of the original Hermitian matrix,  
 *          and if COMPZ = 'I', Z contains the orthonormal eigenvectors  
 *          of the symmetric tridiagonal matrix.  
 *          If COMPZ = 'N', then Z is not referenced.  
 *  
 *  LDZ     (input) INTEGER  
 *          The leading dimension of the array Z.  LDZ >= 1, and if  
 *          eigenvectors are desired, then  LDZ >= max(1,N).  
 *  
 *  WORK    (workspace) DOUBLE PRECISION array, dimension (max(1,2*N-2))  
 *          If COMPZ = 'N', then WORK is not referenced.  
 *  
 *  INFO    (output) INTEGER  
 *          = 0:  successful exit  
 *          < 0:  if INFO = -i, the i-th argument had an illegal value  
 *          > 0:  the algorithm has failed to find all the eigenvalues in  
 *                a total of 30*N iterations; if INFO = i, then i  
 *                elements of E have not converged to zero; on exit, D  
 *                and E contain the elements of a symmetric tridiagonal  
 *                matrix which is unitarily similar to the original  
 *                matrix.  
 *  
 *  =====================================================================  *  =====================================================================
 *  *
 *     .. Parameters ..  *     .. Parameters ..
Removed from v.1.7  
changed lines
  Added in v.1.8

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