LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
 subroutine zchkbk ( integer NIN, integer NOUT )

ZCHKBK

Purpose:
``` ZCHKBK tests ZGEBAK, a routine for backward transformation of
the computed right or left eigenvectors if the orginal matrix
was preprocessed by balance subroutine ZGEBAL.```
Parameters
 [in] NIN ``` NIN is INTEGER The logical unit number for input. NIN > 0.``` [in] NOUT ``` NOUT is INTEGER The logical unit number for output. NOUT > 0.```
Date
November 2011

Definition at line 57 of file zchkbk.f.

57 *
58 * -- LAPACK test routine (version 3.4.0) --
59 * -- LAPACK is a software package provided by Univ. of Tennessee, --
60 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
61 * November 2011
62 *
63 * .. Scalar Arguments ..
64  INTEGER nin, nout
65 * ..
66 *
67 * ======================================================================
68 *
69 * .. Parameters ..
70  INTEGER lde
71  parameter ( lde = 20 )
72  DOUBLE PRECISION zero
73  parameter ( zero = 0.0d0 )
74 * ..
75 * .. Local Scalars ..
76  INTEGER i, ihi, ilo, info, j, knt, n, ninfo
77  DOUBLE PRECISION eps, rmax, safmin, vmax, x
78  COMPLEX*16 cdum
79 * ..
80 * .. Local Arrays ..
81  INTEGER lmax( 2 )
82  DOUBLE PRECISION scale( lde )
83  COMPLEX*16 e( lde, lde ), ein( lde, lde )
84 * ..
85 * .. External Functions ..
86  DOUBLE PRECISION dlamch
87  EXTERNAL dlamch
88 * ..
89 * .. External Subroutines ..
90  EXTERNAL zgebak
91 * ..
92 * .. Intrinsic Functions ..
93  INTRINSIC abs, dble, dimag, max
94 * ..
95 * .. Statement Functions ..
96  DOUBLE PRECISION cabs1
97 * ..
98 * .. Statement Function definitions ..
99  cabs1( cdum ) = abs( dble( cdum ) ) + abs( dimag( cdum ) )
100 * ..
101 * .. Executable Statements ..
102 *
103  lmax( 1 ) = 0
104  lmax( 2 ) = 0
105  ninfo = 0
106  knt = 0
107  rmax = zero
108  eps = dlamch( 'E' )
109  safmin = dlamch( 'S' )
110 *
111  10 CONTINUE
112 *
113  READ( nin, fmt = * )n, ilo, ihi
114  IF( n.EQ.0 )
115  \$ GO TO 60
116 *
117  READ( nin, fmt = * )( scale( i ), i = 1, n )
118  DO 20 i = 1, n
119  READ( nin, fmt = * )( e( i, j ), j = 1, n )
120  20 CONTINUE
121 *
122  DO 30 i = 1, n
123  READ( nin, fmt = * )( ein( i, j ), j = 1, n )
124  30 CONTINUE
125 *
126  knt = knt + 1
127  CALL zgebak( 'B', 'R', n, ilo, ihi, scale, n, e, lde, info )
128 *
129  IF( info.NE.0 ) THEN
130  ninfo = ninfo + 1
131  lmax( 1 ) = knt
132  END IF
133 *
134  vmax = zero
135  DO 50 i = 1, n
136  DO 40 j = 1, n
137  x = cabs1( e( i, j )-ein( i, j ) ) / eps
138  IF( cabs1( e( i, j ) ).GT.safmin )
139  \$ x = x / cabs1( e( i, j ) )
140  vmax = max( vmax, x )
141  40 CONTINUE
142  50 CONTINUE
143 *
144  IF( vmax.GT.rmax ) THEN
145  lmax( 2 ) = knt
146  rmax = vmax
147  END IF
148 *
149  GO TO 10
150 *
151  60 CONTINUE
152 *
153  WRITE( nout, fmt = 9999 )
154  9999 FORMAT( 1x, '.. test output of ZGEBAK .. ' )
155 *
156  WRITE( nout, fmt = 9998 )rmax
157  9998 FORMAT( 1x, 'value of largest test error = ', d12.3 )
158  WRITE( nout, fmt = 9997 )lmax( 1 )
159  9997 FORMAT( 1x, 'example number where info is not zero = ', i4 )
160  WRITE( nout, fmt = 9996 )lmax( 2 )
161  9996 FORMAT( 1x, 'example number having largest error = ', i4 )
162  WRITE( nout, fmt = 9995 )ninfo
163  9995 FORMAT( 1x, 'number of examples where info is not 0 = ', i4 )
164  WRITE( nout, fmt = 9994 )knt
165  9994 FORMAT( 1x, 'total number of examples tested = ', i4 )
166 *
167  RETURN
168 *
169 * End of ZCHKBK
170 *
double precision function dlamch(CMACH)
DLAMCH
Definition: dlamch.f:65
subroutine zgebak(JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)
ZGEBAK
Definition: zgebak.f:133
logical function lde(RI, RJ, LR)
Definition: dblat2.f:2945

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