1077 lines
		
	
	
		
			45 KiB
		
	
	
	
		
			Fortran
		
	
	
	
			
		
		
	
	
			1077 lines
		
	
	
		
			45 KiB
		
	
	
	
		
			Fortran
		
	
	
	
| *> \brief \b SGSVJ0 pre-processor for the routine sgesvj.
 | |
| *
 | |
| *  =========== DOCUMENTATION ===========
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| *
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| * Online html documentation available at
 | |
| *            http://www.netlib.org/lapack/explore-html/
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| *
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| *> \htmlonly
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| *> Download SGSVJ0 + dependencies
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| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sgsvj0.f">
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| *> [TGZ]</a>
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| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sgsvj0.f">
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| *> [ZIP]</a>
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| *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sgsvj0.f">
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| *> [TXT]</a>
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| *> \endhtmlonly
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| *
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| *  Definition:
 | |
| *  ===========
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| *
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| *       SUBROUTINE SGSVJ0( JOBV, M, N, A, LDA, D, SVA, MV, V, LDV, EPS,
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| *                          SFMIN, TOL, NSWEEP, WORK, LWORK, INFO )
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| *
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| *       .. Scalar Arguments ..
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| *       INTEGER            INFO, LDA, LDV, LWORK, M, MV, N, NSWEEP
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| *       REAL               EPS, SFMIN, TOL
 | |
| *       CHARACTER*1        JOBV
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| *       ..
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| *       .. Array Arguments ..
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| *       REAL               A( LDA, * ), SVA( N ), D( N ), V( LDV, * ),
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| *      $                   WORK( LWORK )
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| *       ..
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| *
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| *
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| *> \par Purpose:
 | |
| *  =============
 | |
| *>
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| *> \verbatim
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| *>
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| *> SGSVJ0 is called from SGESVJ as a pre-processor and that is its main
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| *> purpose. It applies Jacobi rotations in the same way as SGESVJ does, but
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| *> it does not check convergence (stopping criterion). Few tuning
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| *> parameters (marked by [TP]) are available for the implementer.
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| *> \endverbatim
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| *
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| *  Arguments:
 | |
| *  ==========
 | |
| *
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| *> \param[in] JOBV
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| *> \verbatim
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| *>          JOBV is CHARACTER*1
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| *>          Specifies whether the output from this procedure is used
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| *>          to compute the matrix V:
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| *>          = 'V': the product of the Jacobi rotations is accumulated
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| *>                 by postmultiplying the N-by-N array V.
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| *>                (See the description of V.)
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| *>          = 'A': the product of the Jacobi rotations is accumulated
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| *>                 by postmultiplying the MV-by-N array V.
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| *>                (See the descriptions of MV and V.)
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| *>          = 'N': the Jacobi rotations are not accumulated.
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| *> \endverbatim
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| *>
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| *> \param[in] M
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| *> \verbatim
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| *>          M is INTEGER
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| *>          The number of rows of the input matrix A.  M >= 0.
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| *> \endverbatim
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| *>
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| *> \param[in] N
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| *> \verbatim
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| *>          N is INTEGER
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| *>          The number of columns of the input matrix A.
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| *>          M >= N >= 0.
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| *> \endverbatim
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| *>
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| *> \param[in,out] A
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| *> \verbatim
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| *>          A is REAL array, dimension (LDA,N)
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| *>          On entry, M-by-N matrix A, such that A*diag(D) represents
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| *>          the input matrix.
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| *>          On exit,
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| *>          A_onexit * D_onexit represents the input matrix A*diag(D)
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| *>          post-multiplied by a sequence of Jacobi rotations, where the
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| *>          rotation threshold and the total number of sweeps are given in
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| *>          TOL and NSWEEP, respectively.
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| *>          (See the descriptions of D, TOL and NSWEEP.)
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| *> \endverbatim
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| *>
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| *> \param[in] LDA
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| *> \verbatim
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| *>          LDA is INTEGER
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| *>          The leading dimension of the array A.  LDA >= max(1,M).
 | |
| *> \endverbatim
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| *>
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| *> \param[in,out] D
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| *> \verbatim
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| *>          D is REAL array, dimension (N)
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| *>          The array D accumulates the scaling factors from the fast scaled
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| *>          Jacobi rotations.
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| *>          On entry, A*diag(D) represents the input matrix.
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| *>          On exit, A_onexit*diag(D_onexit) represents the input matrix
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| *>          post-multiplied by a sequence of Jacobi rotations, where the
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| *>          rotation threshold and the total number of sweeps are given in
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| *>          TOL and NSWEEP, respectively.
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| *>          (See the descriptions of A, TOL and NSWEEP.)
 | |
| *> \endverbatim
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| *>
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| *> \param[in,out] SVA
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| *> \verbatim
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| *>          SVA is REAL array, dimension (N)
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| *>          On entry, SVA contains the Euclidean norms of the columns of
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| *>          the matrix A*diag(D).
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| *>          On exit, SVA contains the Euclidean norms of the columns of
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| *>          the matrix onexit*diag(D_onexit).
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| *> \endverbatim
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| *>
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| *> \param[in] MV
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| *> \verbatim
 | |
| *>          MV is INTEGER
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| *>          If JOBV = 'A', then MV rows of V are post-multiplied by a
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| *>                           sequence of Jacobi rotations.
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| *>          If JOBV = 'N',   then MV is not referenced.
 | |
| *> \endverbatim
 | |
| *>
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| *> \param[in,out] V
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| *> \verbatim
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| *>          V is REAL array, dimension (LDV,N)
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| *>          If JOBV = 'V' then N rows of V are post-multiplied by a
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| *>                           sequence of Jacobi rotations.
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| *>          If JOBV = 'A' then MV rows of V are post-multiplied by a
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| *>                           sequence of Jacobi rotations.
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| *>          If JOBV = 'N',   then V is not referenced.
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| *> \endverbatim
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| *>
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| *> \param[in] LDV
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| *> \verbatim
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| *>          LDV is INTEGER
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| *>          The leading dimension of the array V,  LDV >= 1.
 | |
| *>          If JOBV = 'V', LDV >= N.
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| *>          If JOBV = 'A', LDV >= MV.
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| *> \endverbatim
 | |
| *>
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| *> \param[in] EPS
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| *> \verbatim
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| *>          EPS is REAL
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| *>          EPS = SLAMCH('Epsilon')
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| *> \endverbatim
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| *>
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| *> \param[in] SFMIN
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| *> \verbatim
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| *>          SFMIN is REAL
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| *>          SFMIN = SLAMCH('Safe Minimum')
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| *> \endverbatim
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| *>
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| *> \param[in] TOL
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| *> \verbatim
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| *>          TOL is REAL
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| *>          TOL is the threshold for Jacobi rotations. For a pair
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| *>          A(:,p), A(:,q) of pivot columns, the Jacobi rotation is
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| *>          applied only if ABS(COS(angle(A(:,p),A(:,q)))) > TOL.
 | |
| *> \endverbatim
 | |
| *>
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| *> \param[in] NSWEEP
 | |
| *> \verbatim
 | |
| *>          NSWEEP is INTEGER
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| *>          NSWEEP is the number of sweeps of Jacobi rotations to be
 | |
| *>          performed.
 | |
| *> \endverbatim
 | |
| *>
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| *> \param[out] WORK
 | |
| *> \verbatim
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| *>          WORK is REAL array, dimension (LWORK)
 | |
| *> \endverbatim
 | |
| *>
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| *> \param[in] LWORK
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| *> \verbatim
 | |
| *>          LWORK is INTEGER
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| *>          LWORK is the dimension of WORK. LWORK >= M.
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| *> \endverbatim
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| *>
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| *> \param[out] INFO
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| *> \verbatim
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| *>          INFO is INTEGER
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| *>          = 0:  successful exit.
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| *>          < 0:  if INFO = -i, then the i-th argument had an illegal value
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| *> \endverbatim
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| *
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| *  Authors:
 | |
| *  ========
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| *
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| *> \author Univ. of Tennessee
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| *> \author Univ. of California Berkeley
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| *> \author Univ. of Colorado Denver
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| *> \author NAG Ltd.
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| *
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| *> \ingroup realOTHERcomputational
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| *
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| *> \par Further Details:
 | |
| *  =====================
 | |
| *>
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| *> SGSVJ0 is used just to enable SGESVJ to call a simplified version of
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| *> itself to work on a submatrix of the original matrix.
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| *>
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| *> \par Contributors:
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| *  ==================
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| *>
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| *> Zlatko Drmac (Zagreb, Croatia) and Kresimir Veselic (Hagen, Germany)
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| *>
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| *> \par Bugs, Examples and Comments:
 | |
| *  =================================
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| *>
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| *> Please report all bugs and send interesting test examples and comments to
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| *> drmac@math.hr. Thank you.
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| *
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| *  =====================================================================
 | |
|       SUBROUTINE SGSVJ0( JOBV, M, N, A, LDA, D, SVA, MV, V, LDV, EPS,
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|      $                   SFMIN, TOL, NSWEEP, WORK, LWORK, INFO )
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| *
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| *  -- LAPACK computational routine --
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| *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
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| *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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| *
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| *     .. Scalar Arguments ..
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|       INTEGER            INFO, LDA, LDV, LWORK, M, MV, N, NSWEEP
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|       REAL               EPS, SFMIN, TOL
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|       CHARACTER*1        JOBV
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| *     ..
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| *     .. Array Arguments ..
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|       REAL               A( LDA, * ), SVA( N ), D( N ), V( LDV, * ),
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|      $                   WORK( LWORK )
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| *     ..
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| *
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| *  =====================================================================
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| *
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| *     .. Local Parameters ..
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|       REAL               ZERO, HALF, ONE
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|       PARAMETER          ( ZERO = 0.0E0, HALF = 0.5E0, ONE = 1.0E0)
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| *     ..
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| *     .. Local Scalars ..
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|       REAL               AAPP, AAPP0, AAPQ, AAQQ, APOAQ, AQOAP, BIG,
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|      $                   BIGTHETA, CS, MXAAPQ, MXSINJ, ROOTBIG, ROOTEPS,
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|      $                   ROOTSFMIN, ROOTTOL, SMALL, SN, T, TEMP1, THETA,
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|      $                   THSIGN
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|       INTEGER            BLSKIP, EMPTSW, i, ibr, IERR, igl, IJBLSK, ir1,
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|      $                   ISWROT, jbc, jgl, KBL, LKAHEAD, MVL, NBL,
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|      $                   NOTROT, p, PSKIPPED, q, ROWSKIP, SWBAND
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|       LOGICAL            APPLV, ROTOK, RSVEC
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| *     ..
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| *     .. Local Arrays ..
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|       REAL               FASTR( 5 )
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| *     ..
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| *     .. Intrinsic Functions ..
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|       INTRINSIC          ABS, MAX, FLOAT, MIN, SIGN, SQRT
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| *     ..
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| *     .. External Functions ..
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|       REAL               SDOT, SNRM2
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|       INTEGER            ISAMAX
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|       LOGICAL            LSAME
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|       EXTERNAL           ISAMAX, LSAME, SDOT, SNRM2
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| *     ..
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| *     .. External Subroutines ..
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|       EXTERNAL           SAXPY, SCOPY, SLASCL, SLASSQ, SROTM, SSWAP,
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|      $                   XERBLA
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| *     ..
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| *     .. Executable Statements ..
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| *
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| *     Test the input parameters.
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| *
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|       APPLV = LSAME( JOBV, 'A' )
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|       RSVEC = LSAME( JOBV, 'V' )
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|       IF( .NOT.( RSVEC .OR. APPLV .OR. LSAME( JOBV, 'N' ) ) ) THEN
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|          INFO = -1
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|       ELSE IF( M.LT.0 ) THEN
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|          INFO = -2
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|       ELSE IF( ( N.LT.0 ) .OR. ( N.GT.M ) ) THEN
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|          INFO = -3
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|       ELSE IF( LDA.LT.M ) THEN
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|          INFO = -5
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|       ELSE IF( ( RSVEC.OR.APPLV ) .AND. ( MV.LT.0 ) ) THEN
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|          INFO = -8
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|       ELSE IF( ( RSVEC.AND.( LDV.LT.N ) ).OR.
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|      $         ( APPLV.AND.( LDV.LT.MV ) ) ) THEN
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|          INFO = -10
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|       ELSE IF( TOL.LE.EPS ) THEN
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|          INFO = -13
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|       ELSE IF( NSWEEP.LT.0 ) THEN
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|          INFO = -14
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|       ELSE IF( LWORK.LT.M ) THEN
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|          INFO = -16
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|       ELSE
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|          INFO = 0
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|       END IF
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| *
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| *     #:(
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|       IF( INFO.NE.0 ) THEN
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|          CALL XERBLA( 'SGSVJ0', -INFO )
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|          RETURN
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|       END IF
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| *
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|       IF( RSVEC ) THEN
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|          MVL = N
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|       ELSE IF( APPLV ) THEN
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|          MVL = MV
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|       END IF
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|       RSVEC = RSVEC .OR. APPLV
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| 
 | |
|       ROOTEPS = SQRT( EPS )
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|       ROOTSFMIN = SQRT( SFMIN )
 | |
|       SMALL = SFMIN / EPS
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|       BIG = ONE / SFMIN
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|       ROOTBIG = ONE / ROOTSFMIN
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|       BIGTHETA = ONE / ROOTEPS
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|       ROOTTOL = SQRT( TOL )
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| *
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| *     .. Row-cyclic Jacobi SVD algorithm with column pivoting ..
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| *
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|       EMPTSW = ( N*( N-1 ) ) / 2
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|       NOTROT = 0
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|       FASTR( 1 ) = ZERO
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| *
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| *     .. Row-cyclic pivot strategy with de Rijk's pivoting ..
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| *
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| 
 | |
|       SWBAND = 0
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| *[TP] SWBAND is a tuning parameter. It is meaningful and effective
 | |
| *     if SGESVJ is used as a computational routine in the preconditioned
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| *     Jacobi SVD algorithm SGESVJ. For sweeps i=1:SWBAND the procedure
 | |
| *     ......
 | |
| 
 | |
|       KBL = MIN( 8, N )
 | |
| *[TP] KBL is a tuning parameter that defines the tile size in the
 | |
| *     tiling of the p-q loops of pivot pairs. In general, an optimal
 | |
| *     value of KBL depends on the matrix dimensions and on the
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| *     parameters of the computer's memory.
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| *
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|       NBL = N / KBL
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|       IF( ( NBL*KBL ).NE.N )NBL = NBL + 1
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| 
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|       BLSKIP = ( KBL**2 ) + 1
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| *[TP] BLKSKIP is a tuning parameter that depends on SWBAND and KBL.
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| 
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|       ROWSKIP = MIN( 5, KBL )
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| *[TP] ROWSKIP is a tuning parameter.
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| 
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|       LKAHEAD = 1
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| *[TP] LKAHEAD is a tuning parameter.
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|       SWBAND = 0
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|       PSKIPPED = 0
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| *
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|       DO 1993 i = 1, NSWEEP
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| *     .. go go go ...
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| *
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|          MXAAPQ = ZERO
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|          MXSINJ = ZERO
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|          ISWROT = 0
 | |
| *
 | |
|          NOTROT = 0
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|          PSKIPPED = 0
 | |
| *
 | |
|          DO 2000 ibr = 1, NBL
 | |
| 
 | |
|             igl = ( ibr-1 )*KBL + 1
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| *
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|             DO 1002 ir1 = 0, MIN( LKAHEAD, NBL-ibr )
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| *
 | |
|                igl = igl + ir1*KBL
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| *
 | |
|                DO 2001 p = igl, MIN( igl+KBL-1, N-1 )
 | |
| 
 | |
| *     .. de Rijk's pivoting
 | |
|                   q = ISAMAX( N-p+1, SVA( p ), 1 ) + p - 1
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|                   IF( p.NE.q ) THEN
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|                      CALL SSWAP( M, A( 1, p ), 1, A( 1, q ), 1 )
 | |
|                      IF( RSVEC )CALL SSWAP( MVL, V( 1, p ), 1,
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|      $                                      V( 1, q ), 1 )
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|                      TEMP1 = SVA( p )
 | |
|                      SVA( p ) = SVA( q )
 | |
|                      SVA( q ) = TEMP1
 | |
|                      TEMP1 = D( p )
 | |
|                      D( p ) = D( q )
 | |
|                      D( q ) = TEMP1
 | |
|                   END IF
 | |
| *
 | |
|                   IF( ir1.EQ.0 ) THEN
 | |
| *
 | |
| *        Column norms are periodically updated by explicit
 | |
| *        norm computation.
 | |
| *        Caveat:
 | |
| *        Some BLAS implementations compute SNRM2(M,A(1,p),1)
 | |
| *        as SQRT(SDOT(M,A(1,p),1,A(1,p),1)), which may result in
 | |
| *        overflow for ||A(:,p)||_2 > SQRT(overflow_threshold), and
 | |
| *        underflow for ||A(:,p)||_2 < SQRT(underflow_threshold).
 | |
| *        Hence, SNRM2 cannot be trusted, not even in the case when
 | |
| *        the true norm is far from the under(over)flow boundaries.
 | |
| *        If properly implemented SNRM2 is available, the IF-THEN-ELSE
 | |
| *        below should read "AAPP = SNRM2( M, A(1,p), 1 ) * D(p)".
 | |
| *
 | |
|                      IF( ( SVA( p ).LT.ROOTBIG ) .AND.
 | |
|      $                   ( SVA( p ).GT.ROOTSFMIN ) ) THEN
 | |
|                         SVA( p ) = SNRM2( M, A( 1, p ), 1 )*D( p )
 | |
|                      ELSE
 | |
|                         TEMP1 = ZERO
 | |
|                         AAPP = ONE
 | |
|                         CALL SLASSQ( M, A( 1, p ), 1, TEMP1, AAPP )
 | |
|                         SVA( p ) = TEMP1*SQRT( AAPP )*D( p )
 | |
|                      END IF
 | |
|                      AAPP = SVA( p )
 | |
|                   ELSE
 | |
|                      AAPP = SVA( p )
 | |
|                   END IF
 | |
| 
 | |
| *
 | |
|                   IF( AAPP.GT.ZERO ) THEN
 | |
| *
 | |
|                      PSKIPPED = 0
 | |
| *
 | |
|                      DO 2002 q = p + 1, MIN( igl+KBL-1, N )
 | |
| *
 | |
|                         AAQQ = SVA( q )
 | |
| 
 | |
|                         IF( AAQQ.GT.ZERO ) THEN
 | |
| *
 | |
|                            AAPP0 = AAPP
 | |
|                            IF( AAQQ.GE.ONE ) THEN
 | |
|                               ROTOK = ( SMALL*AAPP ).LE.AAQQ
 | |
|                               IF( AAPP.LT.( BIG / AAQQ ) ) THEN
 | |
|                                  AAPQ = ( SDOT( M, A( 1, p ), 1, A( 1,
 | |
|      $                                  q ), 1 )*D( p )*D( q ) / AAQQ )
 | |
|      $                                  / AAPP
 | |
|                               ELSE
 | |
|                                  CALL SCOPY( M, A( 1, p ), 1, WORK, 1 )
 | |
|                                  CALL SLASCL( 'G', 0, 0, AAPP, D( p ),
 | |
|      $                                        M, 1, WORK, LDA, IERR )
 | |
|                                  AAPQ = SDOT( M, WORK, 1, A( 1, q ),
 | |
|      $                                  1 )*D( q ) / AAQQ
 | |
|                               END IF
 | |
|                            ELSE
 | |
|                               ROTOK = AAPP.LE.( AAQQ / SMALL )
 | |
|                               IF( AAPP.GT.( SMALL / AAQQ ) ) THEN
 | |
|                                  AAPQ = ( SDOT( M, A( 1, p ), 1, A( 1,
 | |
|      $                                  q ), 1 )*D( p )*D( q ) / AAQQ )
 | |
|      $                                  / AAPP
 | |
|                               ELSE
 | |
|                                  CALL SCOPY( M, A( 1, q ), 1, WORK, 1 )
 | |
|                                  CALL SLASCL( 'G', 0, 0, AAQQ, D( q ),
 | |
|      $                                        M, 1, WORK, LDA, IERR )
 | |
|                                  AAPQ = SDOT( M, WORK, 1, A( 1, p ),
 | |
|      $                                  1 )*D( p ) / AAPP
 | |
|                               END IF
 | |
|                            END IF
 | |
| *
 | |
|                            MXAAPQ = MAX( MXAAPQ, ABS( AAPQ ) )
 | |
| *
 | |
| *        TO rotate or NOT to rotate, THAT is the question ...
 | |
| *
 | |
|                            IF( ABS( AAPQ ).GT.TOL ) THEN
 | |
| *
 | |
| *           .. rotate
 | |
| *           ROTATED = ROTATED + ONE
 | |
| *
 | |
|                               IF( ir1.EQ.0 ) THEN
 | |
|                                  NOTROT = 0
 | |
|                                  PSKIPPED = 0
 | |
|                                  ISWROT = ISWROT + 1
 | |
|                               END IF
 | |
| *
 | |
|                               IF( ROTOK ) THEN
 | |
| *
 | |
|                                  AQOAP = AAQQ / AAPP
 | |
|                                  APOAQ = AAPP / AAQQ
 | |
|                                  THETA = -HALF*ABS( AQOAP-APOAQ ) / AAPQ
 | |
| *
 | |
|                                  IF( ABS( THETA ).GT.BIGTHETA ) THEN
 | |
| *
 | |
|                                     T = HALF / THETA
 | |
|                                     FASTR( 3 ) = T*D( p ) / D( q )
 | |
|                                     FASTR( 4 ) = -T*D( q ) / D( p )
 | |
|                                     CALL SROTM( M, A( 1, p ), 1,
 | |
|      $                                          A( 1, q ), 1, FASTR )
 | |
|                                     IF( RSVEC )CALL SROTM( MVL,
 | |
|      $                                              V( 1, p ), 1,
 | |
|      $                                              V( 1, q ), 1,
 | |
|      $                                              FASTR )
 | |
|                                     SVA( q ) = AAQQ*SQRT( MAX( ZERO,
 | |
|      $                                         ONE+T*APOAQ*AAPQ ) )
 | |
|                                     AAPP = AAPP*SQRT( MAX( ZERO,
 | |
|      $                                         ONE-T*AQOAP*AAPQ ) )
 | |
|                                     MXSINJ = MAX( MXSINJ, ABS( T ) )
 | |
| *
 | |
|                                  ELSE
 | |
| *
 | |
| *                 .. choose correct signum for THETA and rotate
 | |
| *
 | |
|                                     THSIGN = -SIGN( ONE, AAPQ )
 | |
|                                     T = ONE / ( THETA+THSIGN*
 | |
|      $                                  SQRT( ONE+THETA*THETA ) )
 | |
|                                     CS = SQRT( ONE / ( ONE+T*T ) )
 | |
|                                     SN = T*CS
 | |
| *
 | |
|                                     MXSINJ = MAX( MXSINJ, ABS( SN ) )
 | |
|                                     SVA( q ) = AAQQ*SQRT( MAX( ZERO,
 | |
|      $                                         ONE+T*APOAQ*AAPQ ) )
 | |
|                                     AAPP = AAPP*SQRT( MAX( ZERO,
 | |
|      $                                     ONE-T*AQOAP*AAPQ ) )
 | |
| *
 | |
|                                     APOAQ = D( p ) / D( q )
 | |
|                                     AQOAP = D( q ) / D( p )
 | |
|                                     IF( D( p ).GE.ONE ) THEN
 | |
|                                        IF( D( q ).GE.ONE ) THEN
 | |
|                                           FASTR( 3 ) = T*APOAQ
 | |
|                                           FASTR( 4 ) = -T*AQOAP
 | |
|                                           D( p ) = D( p )*CS
 | |
|                                           D( q ) = D( q )*CS
 | |
|                                           CALL SROTM( M, A( 1, p ), 1,
 | |
|      $                                                A( 1, q ), 1,
 | |
|      $                                                FASTR )
 | |
|                                           IF( RSVEC )CALL SROTM( MVL,
 | |
|      $                                        V( 1, p ), 1, V( 1, q ),
 | |
|      $                                        1, FASTR )
 | |
|                                        ELSE
 | |
|                                           CALL SAXPY( M, -T*AQOAP,
 | |
|      $                                                A( 1, q ), 1,
 | |
|      $                                                A( 1, p ), 1 )
 | |
|                                           CALL SAXPY( M, CS*SN*APOAQ,
 | |
|      $                                                A( 1, p ), 1,
 | |
|      $                                                A( 1, q ), 1 )
 | |
|                                           D( p ) = D( p )*CS
 | |
|                                           D( q ) = D( q ) / CS
 | |
|                                           IF( RSVEC ) THEN
 | |
|                                              CALL SAXPY( MVL, -T*AQOAP,
 | |
|      $                                                   V( 1, q ), 1,
 | |
|      $                                                   V( 1, p ), 1 )
 | |
|                                              CALL SAXPY( MVL,
 | |
|      $                                                   CS*SN*APOAQ,
 | |
|      $                                                   V( 1, p ), 1,
 | |
|      $                                                   V( 1, q ), 1 )
 | |
|                                           END IF
 | |
|                                        END IF
 | |
|                                     ELSE
 | |
|                                        IF( D( q ).GE.ONE ) THEN
 | |
|                                           CALL SAXPY( M, T*APOAQ,
 | |
|      $                                                A( 1, p ), 1,
 | |
|      $                                                A( 1, q ), 1 )
 | |
|                                           CALL SAXPY( M, -CS*SN*AQOAP,
 | |
|      $                                                A( 1, q ), 1,
 | |
|      $                                                A( 1, p ), 1 )
 | |
|                                           D( p ) = D( p ) / CS
 | |
|                                           D( q ) = D( q )*CS
 | |
|                                           IF( RSVEC ) THEN
 | |
|                                              CALL SAXPY( MVL, T*APOAQ,
 | |
|      $                                                   V( 1, p ), 1,
 | |
|      $                                                   V( 1, q ), 1 )
 | |
|                                              CALL SAXPY( MVL,
 | |
|      $                                                   -CS*SN*AQOAP,
 | |
|      $                                                   V( 1, q ), 1,
 | |
|      $                                                   V( 1, p ), 1 )
 | |
|                                           END IF
 | |
|                                        ELSE
 | |
|                                           IF( D( p ).GE.D( q ) ) THEN
 | |
|                                              CALL SAXPY( M, -T*AQOAP,
 | |
|      $                                                   A( 1, q ), 1,
 | |
|      $                                                   A( 1, p ), 1 )
 | |
|                                              CALL SAXPY( M, CS*SN*APOAQ,
 | |
|      $                                                   A( 1, p ), 1,
 | |
|      $                                                   A( 1, q ), 1 )
 | |
|                                              D( p ) = D( p )*CS
 | |
|                                              D( q ) = D( q ) / CS
 | |
|                                              IF( RSVEC ) THEN
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               -T*AQOAP,
 | |
|      $                                               V( 1, q ), 1,
 | |
|      $                                               V( 1, p ), 1 )
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               CS*SN*APOAQ,
 | |
|      $                                               V( 1, p ), 1,
 | |
|      $                                               V( 1, q ), 1 )
 | |
|                                              END IF
 | |
|                                           ELSE
 | |
|                                              CALL SAXPY( M, T*APOAQ,
 | |
|      $                                                   A( 1, p ), 1,
 | |
|      $                                                   A( 1, q ), 1 )
 | |
|                                              CALL SAXPY( M,
 | |
|      $                                                   -CS*SN*AQOAP,
 | |
|      $                                                   A( 1, q ), 1,
 | |
|      $                                                   A( 1, p ), 1 )
 | |
|                                              D( p ) = D( p ) / CS
 | |
|                                              D( q ) = D( q )*CS
 | |
|                                              IF( RSVEC ) THEN
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               T*APOAQ, V( 1, p ),
 | |
|      $                                               1, V( 1, q ), 1 )
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               -CS*SN*AQOAP,
 | |
|      $                                               V( 1, q ), 1,
 | |
|      $                                               V( 1, p ), 1 )
 | |
|                                              END IF
 | |
|                                           END IF
 | |
|                                        END IF
 | |
|                                     END IF
 | |
|                                  END IF
 | |
| *
 | |
|                               ELSE
 | |
| *              .. have to use modified Gram-Schmidt like transformation
 | |
|                                  CALL SCOPY( M, A( 1, p ), 1, WORK, 1 )
 | |
|                                  CALL SLASCL( 'G', 0, 0, AAPP, ONE, M,
 | |
|      $                                        1, WORK, LDA, IERR )
 | |
|                                  CALL SLASCL( 'G', 0, 0, AAQQ, ONE, M,
 | |
|      $                                        1, A( 1, q ), LDA, IERR )
 | |
|                                  TEMP1 = -AAPQ*D( p ) / D( q )
 | |
|                                  CALL SAXPY( M, TEMP1, WORK, 1,
 | |
|      $                                       A( 1, q ), 1 )
 | |
|                                  CALL SLASCL( 'G', 0, 0, ONE, AAQQ, M,
 | |
|      $                                        1, A( 1, q ), LDA, IERR )
 | |
|                                  SVA( q ) = AAQQ*SQRT( MAX( ZERO,
 | |
|      $                                      ONE-AAPQ*AAPQ ) )
 | |
|                                  MXSINJ = MAX( MXSINJ, SFMIN )
 | |
|                               END IF
 | |
| *           END IF ROTOK THEN ... ELSE
 | |
| *
 | |
| *           In the case of cancellation in updating SVA(q), SVA(p)
 | |
| *           recompute SVA(q), SVA(p).
 | |
|                               IF( ( SVA( q ) / AAQQ )**2.LE.ROOTEPS )
 | |
|      $                            THEN
 | |
|                                  IF( ( AAQQ.LT.ROOTBIG ) .AND.
 | |
|      $                               ( AAQQ.GT.ROOTSFMIN ) ) THEN
 | |
|                                     SVA( q ) = SNRM2( M, A( 1, q ), 1 )*
 | |
|      $                                         D( q )
 | |
|                                  ELSE
 | |
|                                     T = ZERO
 | |
|                                     AAQQ = ONE
 | |
|                                     CALL SLASSQ( M, A( 1, q ), 1, T,
 | |
|      $                                           AAQQ )
 | |
|                                     SVA( q ) = T*SQRT( AAQQ )*D( q )
 | |
|                                  END IF
 | |
|                               END IF
 | |
|                               IF( ( AAPP / AAPP0 ).LE.ROOTEPS ) THEN
 | |
|                                  IF( ( AAPP.LT.ROOTBIG ) .AND.
 | |
|      $                               ( AAPP.GT.ROOTSFMIN ) ) THEN
 | |
|                                     AAPP = SNRM2( M, A( 1, p ), 1 )*
 | |
|      $                                     D( p )
 | |
|                                  ELSE
 | |
|                                     T = ZERO
 | |
|                                     AAPP = ONE
 | |
|                                     CALL SLASSQ( M, A( 1, p ), 1, T,
 | |
|      $                                           AAPP )
 | |
|                                     AAPP = T*SQRT( AAPP )*D( p )
 | |
|                                  END IF
 | |
|                                  SVA( p ) = AAPP
 | |
|                               END IF
 | |
| *
 | |
|                            ELSE
 | |
| *        A(:,p) and A(:,q) already numerically orthogonal
 | |
|                               IF( ir1.EQ.0 )NOTROT = NOTROT + 1
 | |
|                               PSKIPPED = PSKIPPED + 1
 | |
|                            END IF
 | |
|                         ELSE
 | |
| *        A(:,q) is zero column
 | |
|                            IF( ir1.EQ.0 )NOTROT = NOTROT + 1
 | |
|                            PSKIPPED = PSKIPPED + 1
 | |
|                         END IF
 | |
| *
 | |
|                         IF( ( i.LE.SWBAND ) .AND.
 | |
|      $                      ( PSKIPPED.GT.ROWSKIP ) ) THEN
 | |
|                            IF( ir1.EQ.0 )AAPP = -AAPP
 | |
|                            NOTROT = 0
 | |
|                            GO TO 2103
 | |
|                         END IF
 | |
| *
 | |
|  2002                CONTINUE
 | |
| *     END q-LOOP
 | |
| *
 | |
|  2103                CONTINUE
 | |
| *     bailed out of q-loop
 | |
| 
 | |
|                      SVA( p ) = AAPP
 | |
| 
 | |
|                   ELSE
 | |
|                      SVA( p ) = AAPP
 | |
|                      IF( ( ir1.EQ.0 ) .AND. ( AAPP.EQ.ZERO ) )
 | |
|      $                   NOTROT = NOTROT + MIN( igl+KBL-1, N ) - p
 | |
|                   END IF
 | |
| *
 | |
|  2001          CONTINUE
 | |
| *     end of the p-loop
 | |
| *     end of doing the block ( ibr, ibr )
 | |
|  1002       CONTINUE
 | |
| *     end of ir1-loop
 | |
| *
 | |
| *........................................................
 | |
| * ... go to the off diagonal blocks
 | |
| *
 | |
|             igl = ( ibr-1 )*KBL + 1
 | |
| *
 | |
|             DO 2010 jbc = ibr + 1, NBL
 | |
| *
 | |
|                jgl = ( jbc-1 )*KBL + 1
 | |
| *
 | |
| *        doing the block at ( ibr, jbc )
 | |
| *
 | |
|                IJBLSK = 0
 | |
|                DO 2100 p = igl, MIN( igl+KBL-1, N )
 | |
| *
 | |
|                   AAPP = SVA( p )
 | |
| *
 | |
|                   IF( AAPP.GT.ZERO ) THEN
 | |
| *
 | |
|                      PSKIPPED = 0
 | |
| *
 | |
|                      DO 2200 q = jgl, MIN( jgl+KBL-1, N )
 | |
| *
 | |
|                         AAQQ = SVA( q )
 | |
| *
 | |
|                         IF( AAQQ.GT.ZERO ) THEN
 | |
|                            AAPP0 = AAPP
 | |
| *
 | |
| *     .. M x 2 Jacobi SVD ..
 | |
| *
 | |
| *        .. Safe Gram matrix computation ..
 | |
| *
 | |
|                            IF( AAQQ.GE.ONE ) THEN
 | |
|                               IF( AAPP.GE.AAQQ ) THEN
 | |
|                                  ROTOK = ( SMALL*AAPP ).LE.AAQQ
 | |
|                               ELSE
 | |
|                                  ROTOK = ( SMALL*AAQQ ).LE.AAPP
 | |
|                               END IF
 | |
|                               IF( AAPP.LT.( BIG / AAQQ ) ) THEN
 | |
|                                  AAPQ = ( SDOT( M, A( 1, p ), 1, A( 1,
 | |
|      $                                  q ), 1 )*D( p )*D( q ) / AAQQ )
 | |
|      $                                  / AAPP
 | |
|                               ELSE
 | |
|                                  CALL SCOPY( M, A( 1, p ), 1, WORK, 1 )
 | |
|                                  CALL SLASCL( 'G', 0, 0, AAPP, D( p ),
 | |
|      $                                        M, 1, WORK, LDA, IERR )
 | |
|                                  AAPQ = SDOT( M, WORK, 1, A( 1, q ),
 | |
|      $                                  1 )*D( q ) / AAQQ
 | |
|                               END IF
 | |
|                            ELSE
 | |
|                               IF( AAPP.GE.AAQQ ) THEN
 | |
|                                  ROTOK = AAPP.LE.( AAQQ / SMALL )
 | |
|                               ELSE
 | |
|                                  ROTOK = AAQQ.LE.( AAPP / SMALL )
 | |
|                               END IF
 | |
|                               IF( AAPP.GT.( SMALL / AAQQ ) ) THEN
 | |
|                                  AAPQ = ( SDOT( M, A( 1, p ), 1, A( 1,
 | |
|      $                                  q ), 1 )*D( p )*D( q ) / AAQQ )
 | |
|      $                                  / AAPP
 | |
|                               ELSE
 | |
|                                  CALL SCOPY( M, A( 1, q ), 1, WORK, 1 )
 | |
|                                  CALL SLASCL( 'G', 0, 0, AAQQ, D( q ),
 | |
|      $                                        M, 1, WORK, LDA, IERR )
 | |
|                                  AAPQ = SDOT( M, WORK, 1, A( 1, p ),
 | |
|      $                                  1 )*D( p ) / AAPP
 | |
|                               END IF
 | |
|                            END IF
 | |
| *
 | |
|                            MXAAPQ = MAX( MXAAPQ, ABS( AAPQ ) )
 | |
| *
 | |
| *        TO rotate or NOT to rotate, THAT is the question ...
 | |
| *
 | |
|                            IF( ABS( AAPQ ).GT.TOL ) THEN
 | |
|                               NOTROT = 0
 | |
| *           ROTATED  = ROTATED + 1
 | |
|                               PSKIPPED = 0
 | |
|                               ISWROT = ISWROT + 1
 | |
| *
 | |
|                               IF( ROTOK ) THEN
 | |
| *
 | |
|                                  AQOAP = AAQQ / AAPP
 | |
|                                  APOAQ = AAPP / AAQQ
 | |
|                                  THETA = -HALF*ABS( AQOAP-APOAQ ) / AAPQ
 | |
|                                  IF( AAQQ.GT.AAPP0 )THETA = -THETA
 | |
| *
 | |
|                                  IF( ABS( THETA ).GT.BIGTHETA ) THEN
 | |
|                                     T = HALF / THETA
 | |
|                                     FASTR( 3 ) = T*D( p ) / D( q )
 | |
|                                     FASTR( 4 ) = -T*D( q ) / D( p )
 | |
|                                     CALL SROTM( M, A( 1, p ), 1,
 | |
|      $                                          A( 1, q ), 1, FASTR )
 | |
|                                     IF( RSVEC )CALL SROTM( MVL,
 | |
|      $                                              V( 1, p ), 1,
 | |
|      $                                              V( 1, q ), 1,
 | |
|      $                                              FASTR )
 | |
|                                     SVA( q ) = AAQQ*SQRT( MAX( ZERO,
 | |
|      $                                         ONE+T*APOAQ*AAPQ ) )
 | |
|                                     AAPP = AAPP*SQRT( MAX( ZERO,
 | |
|      $                                     ONE-T*AQOAP*AAPQ ) )
 | |
|                                     MXSINJ = MAX( MXSINJ, ABS( T ) )
 | |
|                                  ELSE
 | |
| *
 | |
| *                 .. choose correct signum for THETA and rotate
 | |
| *
 | |
|                                     THSIGN = -SIGN( ONE, AAPQ )
 | |
|                                     IF( AAQQ.GT.AAPP0 )THSIGN = -THSIGN
 | |
|                                     T = ONE / ( THETA+THSIGN*
 | |
|      $                                  SQRT( ONE+THETA*THETA ) )
 | |
|                                     CS = SQRT( ONE / ( ONE+T*T ) )
 | |
|                                     SN = T*CS
 | |
|                                     MXSINJ = MAX( MXSINJ, ABS( SN ) )
 | |
|                                     SVA( q ) = AAQQ*SQRT( MAX( ZERO,
 | |
|      $                                         ONE+T*APOAQ*AAPQ ) )
 | |
|                                     AAPP = AAPP*SQRT( MAX( ZERO,
 | |
|      $                                         ONE-T*AQOAP*AAPQ ) )
 | |
| *
 | |
|                                     APOAQ = D( p ) / D( q )
 | |
|                                     AQOAP = D( q ) / D( p )
 | |
|                                     IF( D( p ).GE.ONE ) THEN
 | |
| *
 | |
|                                        IF( D( q ).GE.ONE ) THEN
 | |
|                                           FASTR( 3 ) = T*APOAQ
 | |
|                                           FASTR( 4 ) = -T*AQOAP
 | |
|                                           D( p ) = D( p )*CS
 | |
|                                           D( q ) = D( q )*CS
 | |
|                                           CALL SROTM( M, A( 1, p ), 1,
 | |
|      $                                                A( 1, q ), 1,
 | |
|      $                                                FASTR )
 | |
|                                           IF( RSVEC )CALL SROTM( MVL,
 | |
|      $                                        V( 1, p ), 1, V( 1, q ),
 | |
|      $                                        1, FASTR )
 | |
|                                        ELSE
 | |
|                                           CALL SAXPY( M, -T*AQOAP,
 | |
|      $                                                A( 1, q ), 1,
 | |
|      $                                                A( 1, p ), 1 )
 | |
|                                           CALL SAXPY( M, CS*SN*APOAQ,
 | |
|      $                                                A( 1, p ), 1,
 | |
|      $                                                A( 1, q ), 1 )
 | |
|                                           IF( RSVEC ) THEN
 | |
|                                              CALL SAXPY( MVL, -T*AQOAP,
 | |
|      $                                                   V( 1, q ), 1,
 | |
|      $                                                   V( 1, p ), 1 )
 | |
|                                              CALL SAXPY( MVL,
 | |
|      $                                                   CS*SN*APOAQ,
 | |
|      $                                                   V( 1, p ), 1,
 | |
|      $                                                   V( 1, q ), 1 )
 | |
|                                           END IF
 | |
|                                           D( p ) = D( p )*CS
 | |
|                                           D( q ) = D( q ) / CS
 | |
|                                        END IF
 | |
|                                     ELSE
 | |
|                                        IF( D( q ).GE.ONE ) THEN
 | |
|                                           CALL SAXPY( M, T*APOAQ,
 | |
|      $                                                A( 1, p ), 1,
 | |
|      $                                                A( 1, q ), 1 )
 | |
|                                           CALL SAXPY( M, -CS*SN*AQOAP,
 | |
|      $                                                A( 1, q ), 1,
 | |
|      $                                                A( 1, p ), 1 )
 | |
|                                           IF( RSVEC ) THEN
 | |
|                                              CALL SAXPY( MVL, T*APOAQ,
 | |
|      $                                                   V( 1, p ), 1,
 | |
|      $                                                   V( 1, q ), 1 )
 | |
|                                              CALL SAXPY( MVL,
 | |
|      $                                                   -CS*SN*AQOAP,
 | |
|      $                                                   V( 1, q ), 1,
 | |
|      $                                                   V( 1, p ), 1 )
 | |
|                                           END IF
 | |
|                                           D( p ) = D( p ) / CS
 | |
|                                           D( q ) = D( q )*CS
 | |
|                                        ELSE
 | |
|                                           IF( D( p ).GE.D( q ) ) THEN
 | |
|                                              CALL SAXPY( M, -T*AQOAP,
 | |
|      $                                                   A( 1, q ), 1,
 | |
|      $                                                   A( 1, p ), 1 )
 | |
|                                              CALL SAXPY( M, CS*SN*APOAQ,
 | |
|      $                                                   A( 1, p ), 1,
 | |
|      $                                                   A( 1, q ), 1 )
 | |
|                                              D( p ) = D( p )*CS
 | |
|                                              D( q ) = D( q ) / CS
 | |
|                                              IF( RSVEC ) THEN
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               -T*AQOAP,
 | |
|      $                                               V( 1, q ), 1,
 | |
|      $                                               V( 1, p ), 1 )
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               CS*SN*APOAQ,
 | |
|      $                                               V( 1, p ), 1,
 | |
|      $                                               V( 1, q ), 1 )
 | |
|                                              END IF
 | |
|                                           ELSE
 | |
|                                              CALL SAXPY( M, T*APOAQ,
 | |
|      $                                                   A( 1, p ), 1,
 | |
|      $                                                   A( 1, q ), 1 )
 | |
|                                              CALL SAXPY( M,
 | |
|      $                                                   -CS*SN*AQOAP,
 | |
|      $                                                   A( 1, q ), 1,
 | |
|      $                                                   A( 1, p ), 1 )
 | |
|                                              D( p ) = D( p ) / CS
 | |
|                                              D( q ) = D( q )*CS
 | |
|                                              IF( RSVEC ) THEN
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               T*APOAQ, V( 1, p ),
 | |
|      $                                               1, V( 1, q ), 1 )
 | |
|                                                 CALL SAXPY( MVL,
 | |
|      $                                               -CS*SN*AQOAP,
 | |
|      $                                               V( 1, q ), 1,
 | |
|      $                                               V( 1, p ), 1 )
 | |
|                                              END IF
 | |
|                                           END IF
 | |
|                                        END IF
 | |
|                                     END IF
 | |
|                                  END IF
 | |
| *
 | |
|                               ELSE
 | |
|                                  IF( AAPP.GT.AAQQ ) THEN
 | |
|                                     CALL SCOPY( M, A( 1, p ), 1, WORK,
 | |
|      $                                          1 )
 | |
|                                     CALL SLASCL( 'G', 0, 0, AAPP, ONE,
 | |
|      $                                           M, 1, WORK, LDA, IERR )
 | |
|                                     CALL SLASCL( 'G', 0, 0, AAQQ, ONE,
 | |
|      $                                           M, 1, A( 1, q ), LDA,
 | |
|      $                                           IERR )
 | |
|                                     TEMP1 = -AAPQ*D( p ) / D( q )
 | |
|                                     CALL SAXPY( M, TEMP1, WORK, 1,
 | |
|      $                                          A( 1, q ), 1 )
 | |
|                                     CALL SLASCL( 'G', 0, 0, ONE, AAQQ,
 | |
|      $                                           M, 1, A( 1, q ), LDA,
 | |
|      $                                           IERR )
 | |
|                                     SVA( q ) = AAQQ*SQRT( MAX( ZERO,
 | |
|      $                                         ONE-AAPQ*AAPQ ) )
 | |
|                                     MXSINJ = MAX( MXSINJ, SFMIN )
 | |
|                                  ELSE
 | |
|                                     CALL SCOPY( M, A( 1, q ), 1, WORK,
 | |
|      $                                          1 )
 | |
|                                     CALL SLASCL( 'G', 0, 0, AAQQ, ONE,
 | |
|      $                                           M, 1, WORK, LDA, IERR )
 | |
|                                     CALL SLASCL( 'G', 0, 0, AAPP, ONE,
 | |
|      $                                           M, 1, A( 1, p ), LDA,
 | |
|      $                                           IERR )
 | |
|                                     TEMP1 = -AAPQ*D( q ) / D( p )
 | |
|                                     CALL SAXPY( M, TEMP1, WORK, 1,
 | |
|      $                                          A( 1, p ), 1 )
 | |
|                                     CALL SLASCL( 'G', 0, 0, ONE, AAPP,
 | |
|      $                                           M, 1, A( 1, p ), LDA,
 | |
|      $                                           IERR )
 | |
|                                     SVA( p ) = AAPP*SQRT( MAX( ZERO,
 | |
|      $                                         ONE-AAPQ*AAPQ ) )
 | |
|                                     MXSINJ = MAX( MXSINJ, SFMIN )
 | |
|                                  END IF
 | |
|                               END IF
 | |
| *           END IF ROTOK THEN ... ELSE
 | |
| *
 | |
| *           In the case of cancellation in updating SVA(q)
 | |
| *           .. recompute SVA(q)
 | |
|                               IF( ( SVA( q ) / AAQQ )**2.LE.ROOTEPS )
 | |
|      $                            THEN
 | |
|                                  IF( ( AAQQ.LT.ROOTBIG ) .AND.
 | |
|      $                               ( AAQQ.GT.ROOTSFMIN ) ) THEN
 | |
|                                     SVA( q ) = SNRM2( M, A( 1, q ), 1 )*
 | |
|      $                                         D( q )
 | |
|                                  ELSE
 | |
|                                     T = ZERO
 | |
|                                     AAQQ = ONE
 | |
|                                     CALL SLASSQ( M, A( 1, q ), 1, T,
 | |
|      $                                           AAQQ )
 | |
|                                     SVA( q ) = T*SQRT( AAQQ )*D( q )
 | |
|                                  END IF
 | |
|                               END IF
 | |
|                               IF( ( AAPP / AAPP0 )**2.LE.ROOTEPS ) THEN
 | |
|                                  IF( ( AAPP.LT.ROOTBIG ) .AND.
 | |
|      $                               ( AAPP.GT.ROOTSFMIN ) ) THEN
 | |
|                                     AAPP = SNRM2( M, A( 1, p ), 1 )*
 | |
|      $                                     D( p )
 | |
|                                  ELSE
 | |
|                                     T = ZERO
 | |
|                                     AAPP = ONE
 | |
|                                     CALL SLASSQ( M, A( 1, p ), 1, T,
 | |
|      $                                           AAPP )
 | |
|                                     AAPP = T*SQRT( AAPP )*D( p )
 | |
|                                  END IF
 | |
|                                  SVA( p ) = AAPP
 | |
|                               END IF
 | |
| *              end of OK rotation
 | |
|                            ELSE
 | |
|                               NOTROT = NOTROT + 1
 | |
|                               PSKIPPED = PSKIPPED + 1
 | |
|                               IJBLSK = IJBLSK + 1
 | |
|                            END IF
 | |
|                         ELSE
 | |
|                            NOTROT = NOTROT + 1
 | |
|                            PSKIPPED = PSKIPPED + 1
 | |
|                            IJBLSK = IJBLSK + 1
 | |
|                         END IF
 | |
| *
 | |
|                         IF( ( i.LE.SWBAND ) .AND. ( IJBLSK.GE.BLSKIP ) )
 | |
|      $                      THEN
 | |
|                            SVA( p ) = AAPP
 | |
|                            NOTROT = 0
 | |
|                            GO TO 2011
 | |
|                         END IF
 | |
|                         IF( ( i.LE.SWBAND ) .AND.
 | |
|      $                      ( PSKIPPED.GT.ROWSKIP ) ) THEN
 | |
|                            AAPP = -AAPP
 | |
|                            NOTROT = 0
 | |
|                            GO TO 2203
 | |
|                         END IF
 | |
| *
 | |
|  2200                CONTINUE
 | |
| *        end of the q-loop
 | |
|  2203                CONTINUE
 | |
| *
 | |
|                      SVA( p ) = AAPP
 | |
| *
 | |
|                   ELSE
 | |
|                      IF( AAPP.EQ.ZERO )NOTROT = NOTROT +
 | |
|      $                   MIN( jgl+KBL-1, N ) - jgl + 1
 | |
|                      IF( AAPP.LT.ZERO )NOTROT = 0
 | |
|                   END IF
 | |
| 
 | |
|  2100          CONTINUE
 | |
| *     end of the p-loop
 | |
|  2010       CONTINUE
 | |
| *     end of the jbc-loop
 | |
|  2011       CONTINUE
 | |
| *2011 bailed out of the jbc-loop
 | |
|             DO 2012 p = igl, MIN( igl+KBL-1, N )
 | |
|                SVA( p ) = ABS( SVA( p ) )
 | |
|  2012       CONTINUE
 | |
| *
 | |
|  2000    CONTINUE
 | |
| *2000 :: end of the ibr-loop
 | |
| *
 | |
| *     .. update SVA(N)
 | |
|          IF( ( SVA( N ).LT.ROOTBIG ) .AND. ( SVA( N ).GT.ROOTSFMIN ) )
 | |
|      $       THEN
 | |
|             SVA( N ) = SNRM2( M, A( 1, N ), 1 )*D( N )
 | |
|          ELSE
 | |
|             T = ZERO
 | |
|             AAPP = ONE
 | |
|             CALL SLASSQ( M, A( 1, N ), 1, T, AAPP )
 | |
|             SVA( N ) = T*SQRT( AAPP )*D( N )
 | |
|          END IF
 | |
| *
 | |
| *     Additional steering devices
 | |
| *
 | |
|          IF( ( i.LT.SWBAND ) .AND. ( ( MXAAPQ.LE.ROOTTOL ) .OR.
 | |
|      $       ( ISWROT.LE.N ) ) )SWBAND = i
 | |
| *
 | |
|          IF( ( i.GT.SWBAND+1 ) .AND. ( MXAAPQ.LT.FLOAT( N )*TOL ) .AND.
 | |
|      $       ( FLOAT( N )*MXAAPQ*MXSINJ.LT.TOL ) ) THEN
 | |
|             GO TO 1994
 | |
|          END IF
 | |
| *
 | |
|          IF( NOTROT.GE.EMPTSW )GO TO 1994
 | |
| 
 | |
|  1993 CONTINUE
 | |
| *     end i=1:NSWEEP loop
 | |
| * #:) Reaching this point means that the procedure has completed the given
 | |
| *     number of iterations.
 | |
|       INFO = NSWEEP - 1
 | |
|       GO TO 1995
 | |
|  1994 CONTINUE
 | |
| * #:) Reaching this point means that during the i-th sweep all pivots were
 | |
| *     below the given tolerance, causing early exit.
 | |
| *
 | |
|       INFO = 0
 | |
| * #:) INFO = 0 confirms successful iterations.
 | |
|  1995 CONTINUE
 | |
| *
 | |
| *     Sort the vector D.
 | |
|       DO 5991 p = 1, N - 1
 | |
|          q = ISAMAX( N-p+1, SVA( p ), 1 ) + p - 1
 | |
|          IF( p.NE.q ) THEN
 | |
|             TEMP1 = SVA( p )
 | |
|             SVA( p ) = SVA( q )
 | |
|             SVA( q ) = TEMP1
 | |
|             TEMP1 = D( p )
 | |
|             D( p ) = D( q )
 | |
|             D( q ) = TEMP1
 | |
|             CALL SSWAP( M, A( 1, p ), 1, A( 1, q ), 1 )
 | |
|             IF( RSVEC )CALL SSWAP( MVL, V( 1, p ), 1, V( 1, q ), 1 )
 | |
|          END IF
 | |
|  5991 CONTINUE
 | |
| *
 | |
|       RETURN
 | |
| *     ..
 | |
| *     .. END OF SGSVJ0
 | |
| *     ..
 | |
|       END
 |