LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
cchkbk.f
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00001 *> \brief \b CCHKBK
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       SUBROUTINE CCHKBK( NIN, NOUT )
00012 * 
00013 *       .. Scalar Arguments ..
00014 *       INTEGER            NIN, NOUT
00015 *       ..
00016 *  
00017 *
00018 *> \par Purpose:
00019 *  =============
00020 *>
00021 *> \verbatim
00022 *>
00023 *> CCHKBK tests CGEBAK, a routine for backward transformation of
00024 *> the computed right or left eigenvectors if the orginal matrix
00025 *> was preprocessed by balance subroutine CGEBAL.
00026 *> \endverbatim
00027 *
00028 *  Arguments:
00029 *  ==========
00030 *
00031 *> \param[in] NIN
00032 *> \verbatim
00033 *>          NIN is INTEGER
00034 *>          The logical unit number for input.  NIN > 0.
00035 *> \endverbatim
00036 *>
00037 *> \param[in] NOUT
00038 *> \verbatim
00039 *>          NOUT is INTEGER
00040 *>          The logical unit number for output.  NOUT > 0.
00041 *> \endverbatim
00042 *
00043 *  Authors:
00044 *  ========
00045 *
00046 *> \author Univ. of Tennessee 
00047 *> \author Univ. of California Berkeley 
00048 *> \author Univ. of Colorado Denver 
00049 *> \author NAG Ltd. 
00050 *
00051 *> \date November 2011
00052 *
00053 *> \ingroup complex_eig
00054 *
00055 *  =====================================================================
00056       SUBROUTINE CCHKBK( NIN, NOUT )
00057 *
00058 *  -- LAPACK test routine (version 3.4.0) --
00059 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00060 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00061 *     November 2011
00062 *
00063 *     .. Scalar Arguments ..
00064       INTEGER            NIN, NOUT
00065 *     ..
00066 *
00067 * ======================================================================
00068 *
00069 *     .. Parameters ..
00070       INTEGER            LDE
00071       PARAMETER          ( LDE = 20 )
00072       REAL               ZERO
00073       PARAMETER          ( ZERO = 0.0E0 )
00074 *     ..
00075 *     .. Local Scalars ..
00076       INTEGER            I, IHI, ILO, INFO, J, KNT, N, NINFO
00077       REAL               EPS, RMAX, SAFMIN, VMAX, X
00078       COMPLEX            CDUM
00079 *     ..
00080 *     .. Local Arrays ..
00081       INTEGER            LMAX( 2 )
00082       REAL               SCALE( LDE )
00083       COMPLEX            E( LDE, LDE ), EIN( LDE, LDE )
00084 *     ..
00085 *     .. External Functions ..
00086       REAL               SLAMCH
00087       EXTERNAL           SLAMCH
00088 *     ..
00089 *     .. External Subroutines ..
00090       EXTERNAL           CGEBAK
00091 *     ..
00092 *     .. Intrinsic Functions ..
00093       INTRINSIC          ABS, AIMAG, MAX, REAL
00094 *     ..
00095 *     .. Statement Functions ..
00096       REAL               CABS1
00097 *     ..
00098 *     .. Statement Function definitions ..
00099       CABS1( CDUM ) = ABS( REAL( CDUM ) ) + ABS( AIMAG( CDUM ) )
00100 *     ..
00101 *     .. Executable Statements ..
00102 *
00103       LMAX( 1 ) = 0
00104       LMAX( 2 ) = 0
00105       NINFO = 0
00106       KNT = 0
00107       RMAX = ZERO
00108       EPS = SLAMCH( 'E' )
00109       SAFMIN = SLAMCH( 'S' )
00110 *
00111    10 CONTINUE
00112 *
00113       READ( NIN, FMT = * )N, ILO, IHI
00114       IF( N.EQ.0 )
00115      $   GO TO 60
00116 *
00117       READ( NIN, FMT = * )( SCALE( I ), I = 1, N )
00118       DO 20 I = 1, N
00119          READ( NIN, FMT = * )( E( I, J ), J = 1, N )
00120    20 CONTINUE
00121 *
00122       DO 30 I = 1, N
00123          READ( NIN, FMT = * )( EIN( I, J ), J = 1, N )
00124    30 CONTINUE
00125 *
00126       KNT = KNT + 1
00127       CALL CGEBAK( 'B', 'R', N, ILO, IHI, SCALE, N, E, LDE, INFO )
00128 *
00129       IF( INFO.NE.0 ) THEN
00130          NINFO = NINFO + 1
00131          LMAX( 1 ) = KNT
00132       END IF
00133 *
00134       VMAX = ZERO
00135       DO 50 I = 1, N
00136          DO 40 J = 1, N
00137             X = CABS1( E( I, J )-EIN( I, J ) ) / EPS
00138             IF( CABS1( E( I, J ) ).GT.SAFMIN )
00139      $         X = X / CABS1( E( I, J ) )
00140             VMAX = MAX( VMAX, X )
00141    40    CONTINUE
00142    50 CONTINUE
00143 *
00144       IF( VMAX.GT.RMAX ) THEN
00145          LMAX( 2 ) = KNT
00146          RMAX = VMAX
00147       END IF
00148 *
00149       GO TO 10
00150 *
00151    60 CONTINUE
00152 *
00153       WRITE( NOUT, FMT = 9999 )
00154  9999 FORMAT( 1X, '.. test output of CGEBAK .. ' )
00155 *
00156       WRITE( NOUT, FMT = 9998 )RMAX
00157  9998 FORMAT( 1X, 'value of largest test error             = ', E12.3 )
00158       WRITE( NOUT, FMT = 9997 )LMAX( 1 )
00159  9997 FORMAT( 1X, 'example number where info is not zero   = ', I4 )
00160       WRITE( NOUT, FMT = 9996 )LMAX( 2 )
00161  9996 FORMAT( 1X, 'example number having largest error     = ', I4 )
00162       WRITE( NOUT, FMT = 9995 )NINFO
00163  9995 FORMAT( 1X, 'number of examples where info is not 0  = ', I4 )
00164       WRITE( NOUT, FMT = 9994 )KNT
00165  9994 FORMAT( 1X, 'total number of examples tested         = ', I4 )
00166 *
00167       RETURN
00168 *
00169 *     End of CCHKBK
00170 *
00171       END
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