240 lines
		
	
	
		
			6.5 KiB
		
	
	
	
		
			Fortran
		
	
	
	
			
		
		
	
	
			240 lines
		
	
	
		
			6.5 KiB
		
	
	
	
		
			Fortran
		
	
	
	
*> \brief \b DCHKGK
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*
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*  =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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*            http://www.netlib.org/lapack/explore-html/
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*
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*  Definition:
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*  ===========
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*
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*       SUBROUTINE DCHKGK( NIN, NOUT )
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*
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*       .. Scalar Arguments ..
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*       INTEGER            NIN, NOUT
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*       ..
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*
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*
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*> \par Purpose:
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*  =============
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*>
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*> \verbatim
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*>
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*> DCHKGK tests DGGBAK, a routine for backward balancing  of
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*> a matrix pair (A, B).
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*> \endverbatim
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*
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*  Arguments:
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*  ==========
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*
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*> \param[in] NIN
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*> \verbatim
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*>          NIN is INTEGER
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*>          The logical unit number for input.  NIN > 0.
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*> \endverbatim
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*>
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*> \param[in] NOUT
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*> \verbatim
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*>          NOUT is INTEGER
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*>          The logical unit number for output.  NOUT > 0.
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*> \endverbatim
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*
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*  Authors:
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*  ========
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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 double_eig
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*
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*  =====================================================================
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      SUBROUTINE DCHKGK( NIN, NOUT )
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*
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*  -- LAPACK test 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            NIN, NOUT
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*     ..
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*
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*  =====================================================================
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*
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*     .. Parameters ..
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      INTEGER            LDA, LDB, LDVL, LDVR
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      PARAMETER          ( LDA = 50, LDB = 50, LDVL = 50, LDVR = 50 )
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      INTEGER            LDE, LDF, LDWORK
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      PARAMETER          ( LDE = 50, LDF = 50, LDWORK = 50 )
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      DOUBLE PRECISION   ZERO, ONE
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      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
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*     ..
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*     .. Local Scalars ..
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      INTEGER            I, IHI, ILO, INFO, J, KNT, M, N, NINFO
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      DOUBLE PRECISION   ANORM, BNORM, EPS, RMAX, VMAX
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*     ..
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*     .. Local Arrays ..
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      INTEGER            LMAX( 4 )
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      DOUBLE PRECISION   A( LDA, LDA ), AF( LDA, LDA ), B( LDB, LDB ),
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     $                   BF( LDB, LDB ), E( LDE, LDE ), F( LDF, LDF ),
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     $                   LSCALE( LDA ), RSCALE( LDA ), VL( LDVL, LDVL ),
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     $                   VLF( LDVL, LDVL ), VR( LDVR, LDVR ),
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     $                   VRF( LDVR, LDVR ), WORK( LDWORK, LDWORK )
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*     ..
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*     .. External Functions ..
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      DOUBLE PRECISION   DLAMCH, DLANGE
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      EXTERNAL           DLAMCH, DLANGE
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*     ..
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*     .. External Subroutines ..
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      EXTERNAL           DGEMM, DGGBAK, DGGBAL, DLACPY
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*     ..
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*     .. Intrinsic Functions ..
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      INTRINSIC          ABS, MAX
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*     ..
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*     .. Executable Statements ..
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*
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*     Initialization
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*
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      LMAX( 1 ) = 0
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      LMAX( 2 ) = 0
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      LMAX( 3 ) = 0
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      LMAX( 4 ) = 0
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      NINFO = 0
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      KNT = 0
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      RMAX = ZERO
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*
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      EPS = DLAMCH( 'Precision' )
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*
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   10 CONTINUE
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      READ( NIN, FMT = * )N, M
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      IF( N.EQ.0 )
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     $   GO TO 100
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*
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      DO 20 I = 1, N
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         READ( NIN, FMT = * )( A( I, J ), J = 1, N )
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   20 CONTINUE
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*
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      DO 30 I = 1, N
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         READ( NIN, FMT = * )( B( I, J ), J = 1, N )
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   30 CONTINUE
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*
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      DO 40 I = 1, N
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         READ( NIN, FMT = * )( VL( I, J ), J = 1, M )
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   40 CONTINUE
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*
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      DO 50 I = 1, N
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         READ( NIN, FMT = * )( VR( I, J ), J = 1, M )
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   50 CONTINUE
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*
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      KNT = KNT + 1
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*
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      ANORM = DLANGE( 'M', N, N, A, LDA, WORK )
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      BNORM = DLANGE( 'M', N, N, B, LDB, WORK )
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*
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      CALL DLACPY( 'FULL', N, N, A, LDA, AF, LDA )
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      CALL DLACPY( 'FULL', N, N, B, LDB, BF, LDB )
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*
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      CALL DGGBAL( 'B', N, A, LDA, B, LDB, ILO, IHI, LSCALE, RSCALE,
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     $             WORK, INFO )
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      IF( INFO.NE.0 ) THEN
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         NINFO = NINFO + 1
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         LMAX( 1 ) = KNT
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      END IF
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*
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      CALL DLACPY( 'FULL', N, M, VL, LDVL, VLF, LDVL )
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      CALL DLACPY( 'FULL', N, M, VR, LDVR, VRF, LDVR )
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*
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      CALL DGGBAK( 'B', 'L', N, ILO, IHI, LSCALE, RSCALE, M, VL, LDVL,
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     $             INFO )
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      IF( INFO.NE.0 ) THEN
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         NINFO = NINFO + 1
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         LMAX( 2 ) = KNT
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      END IF
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*
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      CALL DGGBAK( 'B', 'R', N, ILO, IHI, LSCALE, RSCALE, M, VR, LDVR,
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     $             INFO )
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      IF( INFO.NE.0 ) THEN
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         NINFO = NINFO + 1
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         LMAX( 3 ) = KNT
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      END IF
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*
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*     Test of DGGBAK
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*
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*     Check tilde(VL)'*A*tilde(VR) - VL'*tilde(A)*VR
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*     where tilde(A) denotes the transformed matrix.
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*
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      CALL DGEMM( 'N', 'N', N, M, N, ONE, AF, LDA, VR, LDVR, ZERO, WORK,
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     $            LDWORK )
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      CALL DGEMM( 'T', 'N', M, M, N, ONE, VL, LDVL, WORK, LDWORK, ZERO,
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     $            E, LDE )
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*
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      CALL DGEMM( 'N', 'N', N, M, N, ONE, A, LDA, VRF, LDVR, ZERO, WORK,
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     $            LDWORK )
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      CALL DGEMM( 'T', 'N', M, M, N, ONE, VLF, LDVL, WORK, LDWORK, ZERO,
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     $            F, LDF )
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*
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      VMAX = ZERO
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      DO 70 J = 1, M
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         DO 60 I = 1, M
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            VMAX = MAX( VMAX, ABS( E( I, J )-F( I, J ) ) )
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   60    CONTINUE
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   70 CONTINUE
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      VMAX = VMAX / ( EPS*MAX( ANORM, BNORM ) )
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      IF( VMAX.GT.RMAX ) THEN
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         LMAX( 4 ) = KNT
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         RMAX = VMAX
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      END IF
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*
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*     Check tilde(VL)'*B*tilde(VR) - VL'*tilde(B)*VR
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*
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      CALL DGEMM( 'N', 'N', N, M, N, ONE, BF, LDB, VR, LDVR, ZERO, WORK,
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     $            LDWORK )
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      CALL DGEMM( 'T', 'N', M, M, N, ONE, VL, LDVL, WORK, LDWORK, ZERO,
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     $            E, LDE )
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*
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      CALL DGEMM( 'N', 'N', N, M, N, ONE, B, LDB, VRF, LDVR, ZERO, WORK,
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     $            LDWORK )
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      CALL DGEMM( 'T', 'N', M, M, N, ONE, VLF, LDVL, WORK, LDWORK, ZERO,
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     $            F, LDF )
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*
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      VMAX = ZERO
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      DO 90 J = 1, M
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         DO 80 I = 1, M
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            VMAX = MAX( VMAX, ABS( E( I, J )-F( I, J ) ) )
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   80    CONTINUE
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   90 CONTINUE
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      VMAX = VMAX / ( EPS*MAX( ANORM, BNORM ) )
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      IF( VMAX.GT.RMAX ) THEN
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         LMAX( 4 ) = KNT
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         RMAX = VMAX
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      END IF
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*
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      GO TO 10
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*
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  100 CONTINUE
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*
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      WRITE( NOUT, FMT = 9999 )
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 9999 FORMAT( 1X, '.. test output of DGGBAK .. ' )
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*
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      WRITE( NOUT, FMT = 9998 )RMAX
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 9998 FORMAT( ' value of largest test error                  =', D12.3 )
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      WRITE( NOUT, FMT = 9997 )LMAX( 1 )
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 9997 FORMAT( ' example number where DGGBAL info is not 0    =', I4 )
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      WRITE( NOUT, FMT = 9996 )LMAX( 2 )
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 9996 FORMAT( ' example number where DGGBAK(L) info is not 0 =', I4 )
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      WRITE( NOUT, FMT = 9995 )LMAX( 3 )
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 9995 FORMAT( ' example number where DGGBAK(R) info is not 0 =', I4 )
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      WRITE( NOUT, FMT = 9994 )LMAX( 4 )
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 9994 FORMAT( ' example number having largest error          =', I4 )
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      WRITE( NOUT, FMT = 9993 )NINFO
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 9993 FORMAT( ' number of examples where info is not 0       =', I4 )
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      WRITE( NOUT, FMT = 9992 )KNT
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 9992 FORMAT( ' total number of examples tested              =', I4 )
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*
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      RETURN
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*
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*     End of DCHKGK
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*
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      END
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