3 * =========== DOCUMENTATION ===========
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
11 * SUBROUTINE SCHKBK( NIN, NOUT )
13 * .. Scalar Arguments ..
23 *> SCHKBK tests SGEBAK, a routine for backward transformation of
24 *> the computed right or left eigenvectors if the original matrix
25 *> was preprocessed by balance subroutine SGEBAL.
34 *> The logical unit number for input. NIN > 0.
40 *> The logical unit number for output. NOUT > 0.
46 *> \author Univ. of Tennessee
47 *> \author Univ. of California Berkeley
48 *> \author Univ. of Colorado Denver
51 *> \date November 2011
53 *> \ingroup single_eig
55 * =====================================================================
56 SUBROUTINE SCHKBK( NIN, NOUT )
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..--
63 * .. Scalar Arguments ..
67 * ======================================================================
71 PARAMETER ( LDE = 20 )
73 PARAMETER ( ZERO = 0.0E0 )
76 INTEGER I, IHI, ILO, INFO, J, KNT, N, NINFO
77 REAL EPS, RMAX, SAFMIN, VMAX, X
81 REAL E( LDE, LDE ), EIN( LDE, LDE ), SCALE( LDE )
83 * .. External Functions ..
87 * .. External Subroutines ..
90 * .. Intrinsic Functions ..
93 * .. Executable Statements ..
101 SAFMIN = SLAMCH( 'S' )
105 READ( NIN, FMT = * )N, ILO, IHI
109 READ( NIN, FMT = * )( SCALE( I ), I = 1, N )
111 READ( NIN, FMT = * )( E( I, J ), J = 1, N )
115 READ( NIN, FMT = * )( EIN( I, J ), J = 1, N )
119 CALL SGEBAK( 'B', 'R', N, ILO, IHI, SCALE, N, E, LDE, INFO )
129 X = ABS( E( I, J )-EIN( I, J ) ) / EPS
130 IF( ABS( E( I, J ) ).GT.SAFMIN )
131 $ X = X / ABS( E( I, J ) )
132 VMAX = MAX( VMAX, X )
136 IF( VMAX.GT.RMAX ) THEN
145 WRITE( NOUT, FMT = 9999 )
146 9999 FORMAT( 1X, '.. test output of SGEBAK .. ' )
148 WRITE( NOUT, FMT = 9998 )RMAX
149 9998 FORMAT( 1X, 'value of largest test error = ', E12.3 )
150 WRITE( NOUT, FMT = 9997 )LMAX( 1 )
151 9997 FORMAT( 1X, 'example number where info is not zero = ', I4 )
152 WRITE( NOUT, FMT = 9996 )LMAX( 2 )
153 9996 FORMAT( 1X, 'example number having largest error = ', I4 )
154 WRITE( NOUT, FMT = 9995 )NINFO
155 9995 FORMAT( 1X, 'number of examples where info is not 0 = ', I4 )
156 WRITE( NOUT, FMT = 9994 )KNT
157 9994 FORMAT( 1X, 'total number of examples tested = ', I4 )