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version 1.9, 2011/07/22 07:38:08 version 1.10, 2011/11/21 20:43:00
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   *> \brief \b DLATRZ
   *
   *  =========== DOCUMENTATION ===========
   *
   * Online html documentation available at 
   *            http://www.netlib.org/lapack/explore-html/ 
   *
   *> \htmlonly
   *> Download DLATRZ + dependencies 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlatrz.f"> 
   *> [TGZ]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlatrz.f"> 
   *> [ZIP]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlatrz.f"> 
   *> [TXT]</a>
   *> \endhtmlonly 
   *
   *  Definition:
   *  ===========
   *
   *       SUBROUTINE DLATRZ( M, N, L, A, LDA, TAU, WORK )
   * 
   *       .. Scalar Arguments ..
   *       INTEGER            L, LDA, M, N
   *       ..
   *       .. Array Arguments ..
   *       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
   *       ..
   *  
   *
   *> \par Purpose:
   *  =============
   *>
   *> \verbatim
   *>
   *> DLATRZ factors the M-by-(M+L) real upper trapezoidal matrix
   *> [ A1 A2 ] = [ A(1:M,1:M) A(1:M,N-L+1:N) ] as ( R  0 ) * Z, by means
   *> of orthogonal transformations.  Z is an (M+L)-by-(M+L) orthogonal
   *> matrix and, R and A1 are M-by-M upper triangular matrices.
   *> \endverbatim
   *
   *  Arguments:
   *  ==========
   *
   *> \param[in] M
   *> \verbatim
   *>          M is INTEGER
   *>          The number of rows of the matrix A.  M >= 0.
   *> \endverbatim
   *>
   *> \param[in] N
   *> \verbatim
   *>          N is INTEGER
   *>          The number of columns of the matrix A.  N >= 0.
   *> \endverbatim
   *>
   *> \param[in] L
   *> \verbatim
   *>          L is INTEGER
   *>          The number of columns of the matrix A containing the
   *>          meaningful part of the Householder vectors. N-M >= L >= 0.
   *> \endverbatim
   *>
   *> \param[in,out] A
   *> \verbatim
   *>          A is DOUBLE PRECISION array, dimension (LDA,N)
   *>          On entry, the leading M-by-N upper trapezoidal part of the
   *>          array A must contain the matrix to be factorized.
   *>          On exit, the leading M-by-M upper triangular part of A
   *>          contains the upper triangular matrix R, and elements N-L+1 to
   *>          N of the first M rows of A, with the array TAU, represent the
   *>          orthogonal matrix Z as a product of M elementary reflectors.
   *> \endverbatim
   *>
   *> \param[in] LDA
   *> \verbatim
   *>          LDA is INTEGER
   *>          The leading dimension of the array A.  LDA >= max(1,M).
   *> \endverbatim
   *>
   *> \param[out] TAU
   *> \verbatim
   *>          TAU is DOUBLE PRECISION array, dimension (M)
   *>          The scalar factors of the elementary reflectors.
   *> \endverbatim
   *>
   *> \param[out] WORK
   *> \verbatim
   *>          WORK is DOUBLE PRECISION array, dimension (M)
   *> \endverbatim
   *
   *  Authors:
   *  ========
   *
   *> \author Univ. of Tennessee 
   *> \author Univ. of California Berkeley 
   *> \author Univ. of Colorado Denver 
   *> \author NAG Ltd. 
   *
   *> \date November 2011
   *
   *> \ingroup doubleOTHERcomputational
   *
   *> \par Contributors:
   *  ==================
   *>
   *>    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
   *
   *> \par Further Details:
   *  =====================
   *>
   *> \verbatim
   *>
   *>  The factorization is obtained by Householder's method.  The kth
   *>  transformation matrix, Z( k ), which is used to introduce zeros into
   *>  the ( m - k + 1 )th row of A, is given in the form
   *>
   *>     Z( k ) = ( I     0   ),
   *>              ( 0  T( k ) )
   *>
   *>  where
   *>
   *>     T( k ) = I - tau*u( k )*u( k )**T,   u( k ) = (   1    ),
   *>                                                 (   0    )
   *>                                                 ( z( k ) )
   *>
   *>  tau is a scalar and z( k ) is an l element vector. tau and z( k )
   *>  are chosen to annihilate the elements of the kth row of A2.
   *>
   *>  The scalar tau is returned in the kth element of TAU and the vector
   *>  u( k ) in the kth row of A2, such that the elements of z( k ) are
   *>  in  a( k, l + 1 ), ..., a( k, n ). The elements of R are returned in
   *>  the upper triangular part of A1.
   *>
   *>  Z is given by
   *>
   *>     Z =  Z( 1 ) * Z( 2 ) * ... * Z( m ).
   *> \endverbatim
   *>
   *  =====================================================================
       SUBROUTINE DLATRZ( M, N, L, A, LDA, TAU, WORK )        SUBROUTINE DLATRZ( M, N, L, A, LDA, TAU, WORK )
 *  *
 *  -- 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
 *  *
 *     .. Scalar Arguments ..  *     .. Scalar Arguments ..
       INTEGER            L, LDA, M, N        INTEGER            L, LDA, M, N
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       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )        DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
 *     ..  *     ..
 *  *
 *  Purpose  
 *  =======  
 *  
 *  DLATRZ factors the M-by-(M+L) real upper trapezoidal matrix  
 *  [ A1 A2 ] = [ A(1:M,1:M) A(1:M,N-L+1:N) ] as ( R  0 ) * Z, by means  
 *  of orthogonal transformations.  Z is an (M+L)-by-(M+L) orthogonal  
 *  matrix and, R and A1 are M-by-M upper triangular matrices.  
 *  
 *  Arguments  
 *  =========  
 *  
 *  M       (input) INTEGER  
 *          The number of rows of the matrix A.  M >= 0.  
 *  
 *  N       (input) INTEGER  
 *          The number of columns of the matrix A.  N >= 0.  
 *  
 *  L       (input) INTEGER  
 *          The number of columns of the matrix A containing the  
 *          meaningful part of the Householder vectors. N-M >= L >= 0.  
 *  
 *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)  
 *          On entry, the leading M-by-N upper trapezoidal part of the  
 *          array A must contain the matrix to be factorized.  
 *          On exit, the leading M-by-M upper triangular part of A  
 *          contains the upper triangular matrix R, and elements N-L+1 to  
 *          N of the first M rows of A, with the array TAU, represent the  
 *          orthogonal matrix Z as a product of M elementary reflectors.  
 *  
 *  LDA     (input) INTEGER  
 *          The leading dimension of the array A.  LDA >= max(1,M).  
 *  
 *  TAU     (output) DOUBLE PRECISION array, dimension (M)  
 *          The scalar factors of the elementary reflectors.  
 *  
 *  WORK    (workspace) DOUBLE PRECISION array, dimension (M)  
 *  
 *  Further Details  
 *  ===============  
 *  
 *  Based on contributions by  
 *    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA  
 *  
 *  The factorization is obtained by Householder's method.  The kth  
 *  transformation matrix, Z( k ), which is used to introduce zeros into  
 *  the ( m - k + 1 )th row of A, is given in the form  
 *  
 *     Z( k ) = ( I     0   ),  
 *              ( 0  T( k ) )  
 *  
 *  where  
 *  
 *     T( k ) = I - tau*u( k )*u( k )**T,   u( k ) = (   1    ),  
 *                                                 (   0    )  
 *                                                 ( z( k ) )  
 *  
 *  tau is a scalar and z( k ) is an l element vector. tau and z( k )  
 *  are chosen to annihilate the elements of the kth row of A2.  
 *  
 *  The scalar tau is returned in the kth element of TAU and the vector  
 *  u( k ) in the kth row of A2, such that the elements of z( k ) are  
 *  in  a( k, l + 1 ), ..., a( k, n ). The elements of R are returned in  
 *  the upper triangular part of A1.  
 *  
 *  Z is given by  
 *  
 *     Z =  Z( 1 ) * Z( 2 ) * ... * Z( m ).  
 *  
 *  =====================================================================  *  =====================================================================
 *  *
 *     .. Parameters ..  *     .. Parameters ..
Removed from v.1.9  
changed lines
  Added in v.1.10

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