1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
*> \brief \b SCHKBK
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* SUBROUTINE SCHKBK( NIN, NOUT )
*
* .. Scalar Arguments ..
* INTEGER NIN, NOUT
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> SCHKBK tests SGEBAK, a routine for backward transformation of
*> the computed right or left eigenvectors if the original matrix
*> was preprocessed by balance subroutine SGEBAL.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] NIN
*> \verbatim
*> NIN is INTEGER
*> The logical unit number for input. NIN > 0.
*> \endverbatim
*>
*> \param[in] NOUT
*> \verbatim
*> NOUT is INTEGER
*> The logical unit number for output. NOUT > 0.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2011
*
*> \ingroup single_eig
*
* =====================================================================
SUBROUTINE SCHKBK( NIN, NOUT )
*
* -- LAPACK test routine (version 3.4.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2011
*
* .. Scalar Arguments ..
INTEGER NIN, NOUT
* ..
*
* ======================================================================
*
* .. Parameters ..
INTEGER LDE
PARAMETER ( LDE = 20 )
REAL ZERO
PARAMETER ( ZERO = 0.0E0 )
* ..
* .. Local Scalars ..
INTEGER I, IHI, ILO, INFO, J, KNT, N, NINFO
REAL EPS, RMAX, SAFMIN, VMAX, X
* ..
* .. Local Arrays ..
INTEGER LMAX( 2 )
REAL E( LDE, LDE ), EIN( LDE, LDE ), SCALE( LDE )
* ..
* .. External Functions ..
REAL SLAMCH
EXTERNAL SLAMCH
* ..
* .. External Subroutines ..
EXTERNAL SGEBAK
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, MAX
* ..
* .. Executable Statements ..
*
LMAX( 1 ) = 0
LMAX( 2 ) = 0
NINFO = 0
KNT = 0
RMAX = ZERO
EPS = SLAMCH( 'E' )
SAFMIN = SLAMCH( 'S' )
*
10 CONTINUE
*
READ( NIN, FMT = * )N, ILO, IHI
IF( N.EQ.0 )
$ GO TO 60
*
READ( NIN, FMT = * )( SCALE( I ), I = 1, N )
DO 20 I = 1, N
READ( NIN, FMT = * )( E( I, J ), J = 1, N )
20 CONTINUE
*
DO 30 I = 1, N
READ( NIN, FMT = * )( EIN( I, J ), J = 1, N )
30 CONTINUE
*
KNT = KNT + 1
CALL SGEBAK( 'B', 'R', N, ILO, IHI, SCALE, N, E, LDE, INFO )
*
IF( INFO.NE.0 ) THEN
NINFO = NINFO + 1
LMAX( 1 ) = KNT
END IF
*
VMAX = ZERO
DO 50 I = 1, N
DO 40 J = 1, N
X = ABS( E( I, J )-EIN( I, J ) ) / EPS
IF( ABS( E( I, J ) ).GT.SAFMIN )
$ X = X / ABS( E( I, J ) )
VMAX = MAX( VMAX, X )
40 CONTINUE
50 CONTINUE
*
IF( VMAX.GT.RMAX ) THEN
LMAX( 2 ) = KNT
RMAX = VMAX
END IF
*
GO TO 10
*
60 CONTINUE
*
WRITE( NOUT, FMT = 9999 )
9999 FORMAT( 1X, '.. test output of SGEBAK .. ' )
*
WRITE( NOUT, FMT = 9998 )RMAX
9998 FORMAT( 1X, 'value of largest test error = ', E12.3 )
WRITE( NOUT, FMT = 9997 )LMAX( 1 )
9997 FORMAT( 1X, 'example number where info is not zero = ', I4 )
WRITE( NOUT, FMT = 9996 )LMAX( 2 )
9996 FORMAT( 1X, 'example number having largest error = ', I4 )
WRITE( NOUT, FMT = 9995 )NINFO
9995 FORMAT( 1X, 'number of examples where info is not 0 = ', I4 )
WRITE( NOUT, FMT = 9994 )KNT
9994 FORMAT( 1X, 'total number of examples tested = ', I4 )
*
RETURN
*
* End of SCHKBK
*
END
|
