164 lines
3.9 KiB
Fortran
164 lines
3.9 KiB
Fortran
*> \brief \b DCHKBK
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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 DCHKBK( 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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*> DCHKBK tests DGEBAK, a routine for backward transformation of
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*> the computed right or left eigenvectors if the orginal matrix
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*> was preprocessed by balance subroutine DGEBAL.
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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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*> \date November 2011
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*
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*> \ingroup double_eig
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*
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* =====================================================================
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SUBROUTINE DCHKBK( NIN, NOUT )
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*
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* -- LAPACK test routine (version 3.4.0) --
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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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* November 2011
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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 LDE
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PARAMETER ( LDE = 20 )
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DOUBLE PRECISION ZERO
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PARAMETER ( ZERO = 0.0D0 )
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* ..
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* .. Local Scalars ..
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INTEGER I, IHI, ILO, INFO, J, KNT, N, NINFO
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DOUBLE PRECISION EPS, RMAX, SAFMIN, VMAX, X
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* ..
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* .. Local Arrays ..
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INTEGER LMAX( 2 )
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DOUBLE PRECISION E( LDE, LDE ), EIN( LDE, LDE ), SCALE( LDE )
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* ..
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* .. External Functions ..
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DOUBLE PRECISION DLAMCH
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EXTERNAL DLAMCH
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* ..
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* .. External Subroutines ..
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EXTERNAL DGEBAK
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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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LMAX( 1 ) = 0
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LMAX( 2 ) = 0
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NINFO = 0
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KNT = 0
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RMAX = ZERO
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EPS = DLAMCH( 'E' )
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SAFMIN = DLAMCH( 'S' )
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*
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10 CONTINUE
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*
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READ( NIN, FMT = * )N, ILO, IHI
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IF( N.EQ.0 )
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$ GO TO 60
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*
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READ( NIN, FMT = * )( SCALE( I ), I = 1, N )
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DO 20 I = 1, N
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READ( NIN, FMT = * )( E( 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 = * )( EIN( I, J ), J = 1, N )
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30 CONTINUE
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*
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KNT = KNT + 1
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CALL DGEBAK( 'B', 'R', N, ILO, IHI, SCALE, N, E, LDE, INFO )
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*
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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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VMAX = ZERO
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DO 50 I = 1, N
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DO 40 J = 1, N
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X = ABS( E( I, J )-EIN( I, J ) ) / EPS
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IF( ABS( E( I, J ) ).GT.SAFMIN )
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$ X = X / ABS( E( I, J ) )
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VMAX = MAX( VMAX, X )
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40 CONTINUE
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50 CONTINUE
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*
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IF( VMAX.GT.RMAX ) THEN
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LMAX( 2 ) = 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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60 CONTINUE
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*
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WRITE( NOUT, FMT = 9999 )
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9999 FORMAT( 1X, '.. test output of DGEBAK .. ' )
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*
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WRITE( NOUT, FMT = 9998 )RMAX
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9998 FORMAT( 1X, 'value of largest test error = ', D12.3 )
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WRITE( NOUT, FMT = 9997 )LMAX( 1 )
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9997 FORMAT( 1X, 'example number where info is not zero = ', I4 )
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WRITE( NOUT, FMT = 9996 )LMAX( 2 )
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9996 FORMAT( 1X, 'example number having largest error = ', I4 )
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WRITE( NOUT, FMT = 9995 )NINFO
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9995 FORMAT( 1X, 'number of examples where info is not 0 = ', I4 )
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WRITE( NOUT, FMT = 9994 )KNT
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9994 FORMAT( 1X, '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 DCHKBK
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*
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END
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