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version 1.8, 2011/07/22 07:38:08 version 1.9, 2011/11/21 20:42:59
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   *> \brief \b DLASY2
   *
   *  =========== DOCUMENTATION ===========
   *
   * Online html documentation available at 
   *            http://www.netlib.org/lapack/explore-html/ 
   *
   *> \htmlonly
   *> Download DLASY2 + dependencies 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlasy2.f"> 
   *> [TGZ]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlasy2.f"> 
   *> [ZIP]</a> 
   *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlasy2.f"> 
   *> [TXT]</a>
   *> \endhtmlonly 
   *
   *  Definition:
   *  ===========
   *
   *       SUBROUTINE DLASY2( LTRANL, LTRANR, ISGN, N1, N2, TL, LDTL, TR,
   *                          LDTR, B, LDB, SCALE, X, LDX, XNORM, INFO )
   * 
   *       .. Scalar Arguments ..
   *       LOGICAL            LTRANL, LTRANR
   *       INTEGER            INFO, ISGN, LDB, LDTL, LDTR, LDX, N1, N2
   *       DOUBLE PRECISION   SCALE, XNORM
   *       ..
   *       .. Array Arguments ..
   *       DOUBLE PRECISION   B( LDB, * ), TL( LDTL, * ), TR( LDTR, * ),
   *      $                   X( LDX, * )
   *       ..
   *  
   *
   *> \par Purpose:
   *  =============
   *>
   *> \verbatim
   *>
   *> DLASY2 solves for the N1 by N2 matrix X, 1 <= N1,N2 <= 2, in
   *>
   *>        op(TL)*X + ISGN*X*op(TR) = SCALE*B,
   *>
   *> where TL is N1 by N1, TR is N2 by N2, B is N1 by N2, and ISGN = 1 or
   *> -1.  op(T) = T or T**T, where T**T denotes the transpose of T.
   *> \endverbatim
   *
   *  Arguments:
   *  ==========
   *
   *> \param[in] LTRANL
   *> \verbatim
   *>          LTRANL is LOGICAL
   *>          On entry, LTRANL specifies the op(TL):
   *>             = .FALSE., op(TL) = TL,
   *>             = .TRUE., op(TL) = TL**T.
   *> \endverbatim
   *>
   *> \param[in] LTRANR
   *> \verbatim
   *>          LTRANR is LOGICAL
   *>          On entry, LTRANR specifies the op(TR):
   *>            = .FALSE., op(TR) = TR,
   *>            = .TRUE., op(TR) = TR**T.
   *> \endverbatim
   *>
   *> \param[in] ISGN
   *> \verbatim
   *>          ISGN is INTEGER
   *>          On entry, ISGN specifies the sign of the equation
   *>          as described before. ISGN may only be 1 or -1.
   *> \endverbatim
   *>
   *> \param[in] N1
   *> \verbatim
   *>          N1 is INTEGER
   *>          On entry, N1 specifies the order of matrix TL.
   *>          N1 may only be 0, 1 or 2.
   *> \endverbatim
   *>
   *> \param[in] N2
   *> \verbatim
   *>          N2 is INTEGER
   *>          On entry, N2 specifies the order of matrix TR.
   *>          N2 may only be 0, 1 or 2.
   *> \endverbatim
   *>
   *> \param[in] TL
   *> \verbatim
   *>          TL is DOUBLE PRECISION array, dimension (LDTL,2)
   *>          On entry, TL contains an N1 by N1 matrix.
   *> \endverbatim
   *>
   *> \param[in] LDTL
   *> \verbatim
   *>          LDTL is INTEGER
   *>          The leading dimension of the matrix TL. LDTL >= max(1,N1).
   *> \endverbatim
   *>
   *> \param[in] TR
   *> \verbatim
   *>          TR is DOUBLE PRECISION array, dimension (LDTR,2)
   *>          On entry, TR contains an N2 by N2 matrix.
   *> \endverbatim
   *>
   *> \param[in] LDTR
   *> \verbatim
   *>          LDTR is INTEGER
   *>          The leading dimension of the matrix TR. LDTR >= max(1,N2).
   *> \endverbatim
   *>
   *> \param[in] B
   *> \verbatim
   *>          B is DOUBLE PRECISION array, dimension (LDB,2)
   *>          On entry, the N1 by N2 matrix B contains the right-hand
   *>          side of the equation.
   *> \endverbatim
   *>
   *> \param[in] LDB
   *> \verbatim
   *>          LDB is INTEGER
   *>          The leading dimension of the matrix B. LDB >= max(1,N1).
   *> \endverbatim
   *>
   *> \param[out] SCALE
   *> \verbatim
   *>          SCALE is DOUBLE PRECISION
   *>          On exit, SCALE contains the scale factor. SCALE is chosen
   *>          less than or equal to 1 to prevent the solution overflowing.
   *> \endverbatim
   *>
   *> \param[out] X
   *> \verbatim
   *>          X is DOUBLE PRECISION array, dimension (LDX,2)
   *>          On exit, X contains the N1 by N2 solution.
   *> \endverbatim
   *>
   *> \param[in] LDX
   *> \verbatim
   *>          LDX is INTEGER
   *>          The leading dimension of the matrix X. LDX >= max(1,N1).
   *> \endverbatim
   *>
   *> \param[out] XNORM
   *> \verbatim
   *>          XNORM is DOUBLE PRECISION
   *>          On exit, XNORM is the infinity-norm of the solution.
   *> \endverbatim
   *>
   *> \param[out] INFO
   *> \verbatim
   *>          INFO is INTEGER
   *>          On exit, INFO is set to
   *>             0: successful exit.
   *>             1: TL and TR have too close eigenvalues, so TL or
   *>                TR is perturbed to get a nonsingular equation.
   *>          NOTE: In the interests of speed, this routine does not
   *>                check the inputs for errors.
   *> \endverbatim
   *
   *  Authors:
   *  ========
   *
   *> \author Univ. of Tennessee 
   *> \author Univ. of California Berkeley 
   *> \author Univ. of Colorado Denver 
   *> \author NAG Ltd. 
   *
   *> \date November 2011
   *
   *> \ingroup doubleSYauxiliary
   *
   *  =====================================================================
       SUBROUTINE DLASY2( LTRANL, LTRANR, ISGN, N1, N2, TL, LDTL, TR,        SUBROUTINE DLASY2( LTRANL, LTRANR, ISGN, N1, N2, TL, LDTL, TR,
      $                   LDTR, B, LDB, SCALE, X, LDX, XNORM, INFO )       $                   LDTR, B, LDB, SCALE, X, LDX, XNORM, INFO )
 *  *
 *  -- 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 ..
       LOGICAL            LTRANL, LTRANR        LOGICAL            LTRANL, LTRANR
Line 16 Line 189
      $                   X( LDX, * )       $                   X( LDX, * )
 *     ..  *     ..
 *  *
 *  Purpose  
 *  =======  
 *  
 *  DLASY2 solves for the N1 by N2 matrix X, 1 <= N1,N2 <= 2, in  
 *  
 *         op(TL)*X + ISGN*X*op(TR) = SCALE*B,  
 *  
 *  where TL is N1 by N1, TR is N2 by N2, B is N1 by N2, and ISGN = 1 or  
 *  -1.  op(T) = T or T**T, where T**T denotes the transpose of T.  
 *  
 *  Arguments  
 *  =========  
 *  
 *  LTRANL  (input) LOGICAL  
 *          On entry, LTRANL specifies the op(TL):  
 *             = .FALSE., op(TL) = TL,  
 *             = .TRUE., op(TL) = TL**T.  
 *  
 *  LTRANR  (input) LOGICAL  
 *          On entry, LTRANR specifies the op(TR):  
 *            = .FALSE., op(TR) = TR,  
 *            = .TRUE., op(TR) = TR**T.  
 *  
 *  ISGN    (input) INTEGER  
 *          On entry, ISGN specifies the sign of the equation  
 *          as described before. ISGN may only be 1 or -1.  
 *  
 *  N1      (input) INTEGER  
 *          On entry, N1 specifies the order of matrix TL.  
 *          N1 may only be 0, 1 or 2.  
 *  
 *  N2      (input) INTEGER  
 *          On entry, N2 specifies the order of matrix TR.  
 *          N2 may only be 0, 1 or 2.  
 *  
 *  TL      (input) DOUBLE PRECISION array, dimension (LDTL,2)  
 *          On entry, TL contains an N1 by N1 matrix.  
 *  
 *  LDTL    (input) INTEGER  
 *          The leading dimension of the matrix TL. LDTL >= max(1,N1).  
 *  
 *  TR      (input) DOUBLE PRECISION array, dimension (LDTR,2)  
 *          On entry, TR contains an N2 by N2 matrix.  
 *  
 *  LDTR    (input) INTEGER  
 *          The leading dimension of the matrix TR. LDTR >= max(1,N2).  
 *  
 *  B       (input) DOUBLE PRECISION array, dimension (LDB,2)  
 *          On entry, the N1 by N2 matrix B contains the right-hand  
 *          side of the equation.  
 *  
 *  LDB     (input) INTEGER  
 *          The leading dimension of the matrix B. LDB >= max(1,N1).  
 *  
 *  SCALE   (output) DOUBLE PRECISION  
 *          On exit, SCALE contains the scale factor. SCALE is chosen  
 *          less than or equal to 1 to prevent the solution overflowing.  
 *  
 *  X       (output) DOUBLE PRECISION array, dimension (LDX,2)  
 *          On exit, X contains the N1 by N2 solution.  
 *  
 *  LDX     (input) INTEGER  
 *          The leading dimension of the matrix X. LDX >= max(1,N1).  
 *  
 *  XNORM   (output) DOUBLE PRECISION  
 *          On exit, XNORM is the infinity-norm of the solution.  
 *  
 *  INFO    (output) INTEGER  
 *          On exit, INFO is set to  
 *             0: successful exit.  
 *             1: TL and TR have too close eigenvalues, so TL or  
 *                TR is perturbed to get a nonsingular equation.  
 *          NOTE: In the interests of speed, this routine does not  
 *                check the inputs for errors.  
 *  
 * =====================================================================  * =====================================================================
 *  *
 *     .. Parameters ..  *     .. Parameters ..
Removed from v.1.8  
changed lines
  Added in v.1.9

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