SUBROUTINE DCHKGK( NIN, NOUT ) * * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. INTEGER NIN, NOUT * .. * * Purpose * ======= * * DCHKGK tests DGGBAK, a routine for backward balancing of * a matrix pair (A, B). * * Arguments * ========= * * NIN (input) INTEGER * The logical unit number for input. NIN > 0. * * NOUT (input) INTEGER * The logical unit number for output. NOUT > 0. * * ===================================================================== * * .. Parameters .. INTEGER LDA, LDB, LDVL, LDVR PARAMETER ( LDA = 50, LDB = 50, LDVL = 50, LDVR = 50 ) INTEGER LDE, LDF, LDWORK PARAMETER ( LDE = 50, LDF = 50, LDWORK = 50 ) DOUBLE PRECISION ZERO, ONE PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 ) * .. * .. Local Scalars .. INTEGER I, IHI, ILO, INFO, J, KNT, M, N, NINFO DOUBLE PRECISION ANORM, BNORM, EPS, RMAX, VMAX * .. * .. Local Arrays .. INTEGER LMAX( 4 ) DOUBLE PRECISION A( LDA, LDA ), AF( LDA, LDA ), B( LDB, LDB ), $ BF( LDB, LDB ), E( LDE, LDE ), F( LDF, LDF ), $ LSCALE( LDA ), RSCALE( LDA ), VL( LDVL, LDVL ), $ VLF( LDVL, LDVL ), VR( LDVR, LDVR ), $ VRF( LDVR, LDVR ), WORK( LDWORK, LDWORK ) * .. * .. External Functions .. DOUBLE PRECISION DLAMCH, DLANGE EXTERNAL DLAMCH, DLANGE * .. * .. External Subroutines .. EXTERNAL DGEMM, DGGBAK, DGGBAL, DLACPY * .. * .. Intrinsic Functions .. INTRINSIC ABS, MAX * .. * .. Executable Statements .. * * Initialization * LMAX( 1 ) = 0 LMAX( 2 ) = 0 LMAX( 3 ) = 0 LMAX( 4 ) = 0 NINFO = 0 KNT = 0 RMAX = ZERO * EPS = DLAMCH( 'Precision' ) * 10 CONTINUE READ( NIN, FMT = * )N, M IF( N.EQ.0 ) $ GO TO 100 * DO 20 I = 1, N READ( NIN, FMT = * )( A( I, J ), J = 1, N ) 20 CONTINUE * DO 30 I = 1, N READ( NIN, FMT = * )( B( I, J ), J = 1, N ) 30 CONTINUE * DO 40 I = 1, N READ( NIN, FMT = * )( VL( I, J ), J = 1, M ) 40 CONTINUE * DO 50 I = 1, N READ( NIN, FMT = * )( VR( I, J ), J = 1, M ) 50 CONTINUE * KNT = KNT + 1 * ANORM = DLANGE( 'M', N, N, A, LDA, WORK ) BNORM = DLANGE( 'M', N, N, B, LDB, WORK ) * CALL DLACPY( 'FULL', N, N, A, LDA, AF, LDA ) CALL DLACPY( 'FULL', N, N, B, LDB, BF, LDB ) * CALL DGGBAL( 'B', N, A, LDA, B, LDB, ILO, IHI, LSCALE, RSCALE, $ WORK, INFO ) IF( INFO.NE.0 ) THEN NINFO = NINFO + 1 LMAX( 1 ) = KNT END IF * CALL DLACPY( 'FULL', N, M, VL, LDVL, VLF, LDVL ) CALL DLACPY( 'FULL', N, M, VR, LDVR, VRF, LDVR ) * CALL DGGBAK( 'B', 'L', N, ILO, IHI, LSCALE, RSCALE, M, VL, LDVL, $ INFO ) IF( INFO.NE.0 ) THEN NINFO = NINFO + 1 LMAX( 2 ) = KNT END IF * CALL DGGBAK( 'B', 'R', N, ILO, IHI, LSCALE, RSCALE, M, VR, LDVR, $ INFO ) IF( INFO.NE.0 ) THEN NINFO = NINFO + 1 LMAX( 3 ) = KNT END IF * * Test of DGGBAK * * Check tilde(VL)'*A*tilde(VR) - VL'*tilde(A)*VR * where tilde(A) denotes the transformed matrix. * CALL DGEMM( 'N', 'N', N, M, N, ONE, AF, LDA, VR, LDVR, ZERO, WORK, $ LDWORK ) CALL DGEMM( 'T', 'N', M, M, N, ONE, VL, LDVL, WORK, LDWORK, ZERO, $ E, LDE ) * CALL DGEMM( 'N', 'N', N, M, N, ONE, A, LDA, VRF, LDVR, ZERO, WORK, $ LDWORK ) CALL DGEMM( 'T', 'N', M, M, N, ONE, VLF, LDVL, WORK, LDWORK, ZERO, $ F, LDF ) * VMAX = ZERO DO 70 J = 1, M DO 60 I = 1, M VMAX = MAX( VMAX, ABS( E( I, J )-F( I, J ) ) ) 60 CONTINUE 70 CONTINUE VMAX = VMAX / ( EPS*MAX( ANORM, BNORM ) ) IF( VMAX.GT.RMAX ) THEN LMAX( 4 ) = KNT RMAX = VMAX END IF * * Check tilde(VL)'*B*tilde(VR) - VL'*tilde(B)*VR * CALL DGEMM( 'N', 'N', N, M, N, ONE, BF, LDB, VR, LDVR, ZERO, WORK, $ LDWORK ) CALL DGEMM( 'T', 'N', M, M, N, ONE, VL, LDVL, WORK, LDWORK, ZERO, $ E, LDE ) * CALL DGEMM( 'N', 'N', N, M, N, ONE, B, LDB, VRF, LDVR, ZERO, WORK, $ LDWORK ) CALL DGEMM( 'T', 'N', M, M, N, ONE, VLF, LDVL, WORK, LDWORK, ZERO, $ F, LDF ) * VMAX = ZERO DO 90 J = 1, M DO 80 I = 1, M VMAX = MAX( VMAX, ABS( E( I, J )-F( I, J ) ) ) 80 CONTINUE 90 CONTINUE VMAX = VMAX / ( EPS*MAX( ANORM, BNORM ) ) IF( VMAX.GT.RMAX ) THEN LMAX( 4 ) = KNT RMAX = VMAX END IF * GO TO 10 * 100 CONTINUE * WRITE( NOUT, FMT = 9999 ) 9999 FORMAT( 1X, '.. test output of DGGBAK .. ' ) * WRITE( NOUT, FMT = 9998 )RMAX 9998 FORMAT( ' value of largest test error =', D12.3 ) WRITE( NOUT, FMT = 9997 )LMAX( 1 ) 9997 FORMAT( ' example number where DGGBAL info is not 0 =', I4 ) WRITE( NOUT, FMT = 9996 )LMAX( 2 ) 9996 FORMAT( ' example number where DGGBAK(L) info is not 0 =', I4 ) WRITE( NOUT, FMT = 9995 )LMAX( 3 ) 9995 FORMAT( ' example number where DGGBAK(R) info is not 0 =', I4 ) WRITE( NOUT, FMT = 9994 )LMAX( 4 ) 9994 FORMAT( ' example number having largest error =', I4 ) WRITE( NOUT, FMT = 9993 )NINFO 9993 FORMAT( ' number of examples where info is not 0 =', I4 ) WRITE( NOUT, FMT = 9992 )KNT 9992 FORMAT( ' total number of examples tested =', I4 ) * RETURN * * End of DCHKGK * END