Diff for /rpl/lapack/lapack/dlasd5.f between versions 1.7 and 1.8

version 1.7, 2010/12/21 13:53:33 version 1.8, 2011/11/21 20:42:58
Line 1 Line 1
   *> \brief \b DLASD5
   *
   *  =========== DOCUMENTATION ===========
   *
   * Online html documentation available at 
   *            http://www.netlib.org/lapack/explore-html/ 
   *
   *> \htmlonly
   *> Download DLASD5 + dependencies 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlasd5.f"> 
   *> [TGZ]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlasd5.f"> 
   *> [ZIP]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlasd5.f"> 
   *> [TXT]</a>
   *> \endhtmlonly 
   *
   *  Definition:
   *  ===========
   *
   *       SUBROUTINE DLASD5( I, D, Z, DELTA, RHO, DSIGMA, WORK )
   * 
   *       .. Scalar Arguments ..
   *       INTEGER            I
   *       DOUBLE PRECISION   DSIGMA, RHO
   *       ..
   *       .. Array Arguments ..
   *       DOUBLE PRECISION   D( 2 ), DELTA( 2 ), WORK( 2 ), Z( 2 )
   *       ..
   *  
   *
   *> \par Purpose:
   *  =============
   *>
   *> \verbatim
   *>
   *> This subroutine computes the square root of the I-th eigenvalue
   *> of a positive symmetric rank-one modification of a 2-by-2 diagonal
   *> matrix
   *>
   *>            diag( D ) * diag( D ) +  RHO * Z * transpose(Z) .
   *>
   *> The diagonal entries in the array D are assumed to satisfy
   *>
   *>            0 <= D(i) < D(j)  for  i < j .
   *>
   *> We also assume RHO > 0 and that the Euclidean norm of the vector
   *> Z is one.
   *> \endverbatim
   *
   *  Arguments:
   *  ==========
   *
   *> \param[in] I
   *> \verbatim
   *>          I is INTEGER
   *>         The index of the eigenvalue to be computed.  I = 1 or I = 2.
   *> \endverbatim
   *>
   *> \param[in] D
   *> \verbatim
   *>          D is DOUBLE PRECISION array, dimension ( 2 )
   *>         The original eigenvalues.  We assume 0 <= D(1) < D(2).
   *> \endverbatim
   *>
   *> \param[in] Z
   *> \verbatim
   *>          Z is DOUBLE PRECISION array, dimension ( 2 )
   *>         The components of the updating vector.
   *> \endverbatim
   *>
   *> \param[out] DELTA
   *> \verbatim
   *>          DELTA is DOUBLE PRECISION array, dimension ( 2 )
   *>         Contains (D(j) - sigma_I) in its  j-th component.
   *>         The vector DELTA contains the information necessary
   *>         to construct the eigenvectors.
   *> \endverbatim
   *>
   *> \param[in] RHO
   *> \verbatim
   *>          RHO is DOUBLE PRECISION
   *>         The scalar in the symmetric updating formula.
   *> \endverbatim
   *>
   *> \param[out] DSIGMA
   *> \verbatim
   *>          DSIGMA is DOUBLE PRECISION
   *>         The computed sigma_I, the I-th updated eigenvalue.
   *> \endverbatim
   *>
   *> \param[out] WORK
   *> \verbatim
   *>          WORK is DOUBLE PRECISION array, dimension ( 2 )
   *>         WORK contains (D(j) + sigma_I) in its  j-th component.
   *> \endverbatim
   *
   *  Authors:
   *  ========
   *
   *> \author Univ. of Tennessee 
   *> \author Univ. of California Berkeley 
   *> \author Univ. of Colorado Denver 
   *> \author NAG Ltd. 
   *
   *> \date November 2011
   *
   *> \ingroup auxOTHERauxiliary
   *
   *> \par Contributors:
   *  ==================
   *>
   *>     Ren-Cang Li, Computer Science Division, University of California
   *>     at Berkeley, USA
   *>
   *  =====================================================================
       SUBROUTINE DLASD5( I, D, Z, DELTA, RHO, DSIGMA, WORK )        SUBROUTINE DLASD5( I, D, Z, DELTA, RHO, DSIGMA, WORK )
 *  *
 *  -- LAPACK auxiliary routine (version 3.2) --  *  -- LAPACK auxiliary 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 ..
       INTEGER            I        INTEGER            I
Line 13 Line 129
       DOUBLE PRECISION   D( 2 ), DELTA( 2 ), WORK( 2 ), Z( 2 )        DOUBLE PRECISION   D( 2 ), DELTA( 2 ), WORK( 2 ), Z( 2 )
 *     ..  *     ..
 *  *
 *  Purpose  
 *  =======  
 *  
 *  This subroutine computes the square root of the I-th eigenvalue  
 *  of a positive symmetric rank-one modification of a 2-by-2 diagonal  
 *  matrix  
 *  
 *             diag( D ) * diag( D ) +  RHO *  Z * transpose(Z) .  
 *  
 *  The diagonal entries in the array D are assumed to satisfy  
 *  
 *             0 <= D(i) < D(j)  for  i < j .  
 *  
 *  We also assume RHO > 0 and that the Euclidean norm of the vector  
 *  Z is one.  
 *  
 *  Arguments  
 *  =========  
 *  
 *  I      (input) INTEGER  
 *         The index of the eigenvalue to be computed.  I = 1 or I = 2.  
 *  
 *  D      (input) DOUBLE PRECISION array, dimension ( 2 )  
 *         The original eigenvalues.  We assume 0 <= D(1) < D(2).  
 *  
 *  Z      (input) DOUBLE PRECISION array, dimension ( 2 )  
 *         The components of the updating vector.  
 *  
 *  DELTA  (output) DOUBLE PRECISION array, dimension ( 2 )  
 *         Contains (D(j) - sigma_I) in its  j-th component.  
 *         The vector DELTA contains the information necessary  
 *         to construct the eigenvectors.  
 *  
 *  RHO    (input) DOUBLE PRECISION  
 *         The scalar in the symmetric updating formula.  
 *  
 *  DSIGMA (output) DOUBLE PRECISION  
 *         The computed sigma_I, the I-th updated eigenvalue.  
 *  
 *  WORK   (workspace) DOUBLE PRECISION array, dimension ( 2 )  
 *         WORK contains (D(j) + sigma_I) in its  j-th component.  
 *  
 *  Further Details  
 *  ===============  
 *  
 *  Based on contributions by  
 *     Ren-Cang Li, Computer Science Division, University of California  
 *     at Berkeley, USA  
 *  
 *  =====================================================================  *  =====================================================================
 *  *
 *     .. Parameters ..  *     .. Parameters ..

Removed from v.1.7  
changed lines
  Added in v.1.8


CVSweb interface <joel.bertrand@systella.fr>