LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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◆ schkbl()

 subroutine schkbl ( integer NIN, integer NOUT )

SCHKBL

Purpose:
``` SCHKBL tests SGEBAL, a routine for balancing a general real
matrix and isolating some of its eigenvalues.```
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.```

Definition at line 53 of file schkbl.f.

54*
55* -- LAPACK test routine --
56* -- LAPACK is a software package provided by Univ. of Tennessee, --
57* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
58*
59* .. Scalar Arguments ..
60 INTEGER NIN, NOUT
61* ..
62*
63* ======================================================================
64*
65* .. Parameters ..
66 INTEGER LDA
67 parameter( lda = 20 )
68 REAL ZERO
69 parameter( zero = 0.0e+0 )
70* ..
71* .. Local Scalars ..
72 INTEGER I, IHI, IHIIN, ILO, ILOIN, INFO, J, KNT, N,
73 \$ NINFO
74 REAL ANORM, MEPS, RMAX, SFMIN, TEMP, VMAX
75* ..
76* .. Local Arrays ..
77 INTEGER LMAX( 3 )
78 REAL A( LDA, LDA ), AIN( LDA, LDA ), DUMMY( 1 ),
79 \$ SCALE( LDA ), SCALIN( LDA )
80* ..
81* .. External Functions ..
82 REAL SLAMCH, SLANGE
83 EXTERNAL slamch, slange
84* ..
85* .. External Subroutines ..
86 EXTERNAL sgebal
87* ..
88* .. Intrinsic Functions ..
89 INTRINSIC abs, max
90* ..
91* .. Executable Statements ..
92*
93 lmax( 1 ) = 0
94 lmax( 2 ) = 0
95 lmax( 3 ) = 0
96 ninfo = 0
97 knt = 0
98 rmax = zero
99 vmax = zero
100 sfmin = slamch( 'S' )
101 meps = slamch( 'E' )
102*
103 10 CONTINUE
104*
105 READ( nin, fmt = * )n
106 IF( n.EQ.0 )
107 \$ GO TO 70
108 DO 20 i = 1, n
109 READ( nin, fmt = * )( a( i, j ), j = 1, n )
110 20 CONTINUE
111*
112 READ( nin, fmt = * )iloin, ihiin
113 DO 30 i = 1, n
114 READ( nin, fmt = * )( ain( i, j ), j = 1, n )
115 30 CONTINUE
116 READ( nin, fmt = * )( scalin( i ), i = 1, n )
117*
118 anorm = slange( 'M', n, n, a, lda, dummy )
119 knt = knt + 1
120*
121 CALL sgebal( 'B', n, a, lda, ilo, ihi, scale, info )
122*
123 IF( info.NE.0 ) THEN
124 ninfo = ninfo + 1
125 lmax( 1 ) = knt
126 END IF
127*
128 IF( ilo.NE.iloin .OR. ihi.NE.ihiin ) THEN
129 ninfo = ninfo + 1
130 lmax( 2 ) = knt
131 END IF
132*
133 DO 50 i = 1, n
134 DO 40 j = 1, n
135 temp = max( a( i, j ), ain( i, j ) )
136 temp = max( temp, sfmin )
137 vmax = max( vmax, abs( a( i, j )-ain( i, j ) ) / temp )
138 40 CONTINUE
139 50 CONTINUE
140*
141 DO 60 i = 1, n
142 temp = max( scale( i ), scalin( i ) )
143 temp = max( temp, sfmin )
144 vmax = max( vmax, abs( scale( i )-scalin( i ) ) / temp )
145 60 CONTINUE
146*
147*
148 IF( vmax.GT.rmax ) THEN
149 lmax( 3 ) = knt
150 rmax = vmax
151 END IF
152*
153 GO TO 10
154*
155 70 CONTINUE
156*
157 WRITE( nout, fmt = 9999 )
158 9999 FORMAT( 1x, '.. test output of SGEBAL .. ' )
159*
160 WRITE( nout, fmt = 9998 )rmax
161 9998 FORMAT( 1x, 'value of largest test error = ', e12.3 )
162 WRITE( nout, fmt = 9997 )lmax( 1 )
163 9997 FORMAT( 1x, 'example number where info is not zero = ', i4 )
164 WRITE( nout, fmt = 9996 )lmax( 2 )
165 9996 FORMAT( 1x, 'example number where ILO or IHI wrong = ', i4 )
166 WRITE( nout, fmt = 9995 )lmax( 3 )
167 9995 FORMAT( 1x, 'example number having largest error = ', i4 )
168 WRITE( nout, fmt = 9994 )ninfo
169 9994 FORMAT( 1x, 'number of examples where info is not 0 = ', i4 )
170 WRITE( nout, fmt = 9993 )knt
171 9993 FORMAT( 1x, 'total number of examples tested = ', i4 )
172*
173 RETURN
174*
175* End of SCHKBL
176*
real function slange(NORM, M, N, A, LDA, WORK)
SLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition: slange.f:114
subroutine sgebal(JOB, N, A, LDA, ILO, IHI, SCALE, INFO)
SGEBAL
Definition: sgebal.f:160
real function slamch(CMACH)
SLAMCH
Definition: slamch.f:68
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