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* MB03LF EXAMPLE PROGRAM TEXT
*
* .. Parameters ..
INTEGER NIN, NOUT
PARAMETER ( NIN = 5, NOUT = 6 )
INTEGER NMAX
PARAMETER ( NMAX = 50 )
INTEGER LDB, LDFG, LDQ, LDU, LDWORK, LDZ, LIWORK
PARAMETER ( LDB = NMAX/2, LDFG = NMAX/2, LDQ = 2*NMAX,
$ LDU = NMAX, LDZ = NMAX,
$ LDWORK = 10*NMAX*NMAX +
$ MAX( NMAX*NMAX +
$ MAX( NMAX/2 + 252, 432 ),
$ MAX( 8*NMAX + 48, 171 ) ),
$ LIWORK = MAX( NMAX + 18, NMAX/2 + 48,
$ 5*NMAX/2 + 1 ) )
*
* .. Local Scalars ..
CHARACTER COMPQ, COMPU, ORTH
INTEGER I, INFO, IWARN, J, M, N, NEIG
*
* .. Local Arrays ..
LOGICAL BWORK( NMAX/2 )
INTEGER IWORK( LIWORK )
DOUBLE PRECISION ALPHAI( NMAX/2 ), ALPHAR( NMAX/2 ),
$ B( LDB, NMAX/2 ), BETA( NMAX/2 ),
$ DWORK( LDWORK ), FG( LDFG, NMAX/2+1 ),
$ Q( LDQ, 2*NMAX ), U( LDU, 2*NMAX ),
$ Z( LDZ, NMAX )
*
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
*
* .. External Subroutines ..
EXTERNAL MB03LF
*
* .. Intrinsic Functions ..
INTRINSIC MAX, MOD
*
* .. Executable Statements ..
*
WRITE( NOUT, FMT = 99999 )
* Skip the heading in the data file and read in the data.
READ( NIN, FMT = * )
READ( NIN, FMT = * ) COMPQ, COMPU, ORTH, N
IF( N.LT.0 .OR. N.GT.NMAX .OR. MOD( N, 2 ).NE.0 ) THEN
WRITE( NOUT, FMT = 99998 ) N
ELSE
M = N/2
READ( NIN, FMT = * ) ( ( Z( I, J ), J = 1, N ), I = 1, N )
READ( NIN, FMT = * ) ( ( B( I, J ), J = 1, M ), I = 1, M )
READ( NIN, FMT = * ) ( ( FG( I, J ), J = 1, M+1 ), I = 1, M )
* Compute the eigenvalues and orthogonal bases of the right
* deflating subspace and companion subspace of a real
* skew-Hamiltonian/Hamiltonian pencil, corresponding to the
* eigenvalues with strictly negative real part.
CALL MB03LF( COMPQ, COMPU, ORTH, N, Z, LDZ, B, LDB, FG, LDFG,
$ NEIG, Q, LDQ, U, LDU, ALPHAR, ALPHAI, BETA, IWORK,
$ LIWORK, DWORK, LDWORK, BWORK, IWARN, INFO )
*
IF( INFO.NE.0 ) THEN
WRITE( NOUT, FMT = 99997 ) INFO
ELSE
WRITE( NOUT, FMT = 99996 )
DO 10 I = 1, N
WRITE( NOUT, FMT = 99995 ) ( Z( I, J ), J = 1, N )
10 CONTINUE
WRITE( NOUT, FMT = 99994 )
WRITE( NOUT, FMT = 99995 ) ( ALPHAR( I ), I = 1, M )
WRITE( NOUT, FMT = 99993 )
WRITE( NOUT, FMT = 99995 ) ( ALPHAI( I ), I = 1, M )
WRITE( NOUT, FMT = 99992 )
WRITE( NOUT, FMT = 99995 ) ( BETA( I ), I = 1, M )
IF( LSAME( COMPQ, 'C' ) .AND. NEIG.GT.0 ) THEN
WRITE( NOUT, FMT = 99991 )
DO 20 I = 1, N
WRITE( NOUT, FMT = 99995 ) ( Q( I, J ), J = 1, NEIG )
20 CONTINUE
END IF
IF( LSAME( COMPU, 'C' ) .AND. NEIG.GT.0 ) THEN
WRITE( NOUT, FMT = 99990 )
DO 30 I = 1, N
WRITE( NOUT, FMT = 99995 ) ( U( I, J ), J = 1, NEIG )
30 CONTINUE
END IF
IF( LSAME( COMPQ, 'C' ) .OR. LSAME( COMPU, 'C' ) )
$ WRITE( NOUT, FMT = 99989 ) NEIG
END IF
END IF
STOP
*
99999 FORMAT ( 'MB03LF EXAMPLE PROGRAM RESULTS', 1X )
99998 FORMAT ( 'N is out of range.', /, 'N = ', I5 )
99997 FORMAT ( 'INFO on exit from MB03LF = ', I2 )
99996 FORMAT (/'The matrix Z on exit is ' )
99995 FORMAT ( 50( 1X, F8.4 ) )
99994 FORMAT (/'The vector ALPHAR is ' )
99993 FORMAT (/'The vector ALPHAI is ' )
99992 FORMAT (/'The vector BETA is ' )
99991 FORMAT (/'The deflating subspace corresponding to the ',
$ 'eigenvalues with negative real part is ' )
99990 FORMAT (/'The companion subspace corresponding to the ',
$ 'eigenvalues with negative real part is ' )
99989 FORMAT (/'The number of eigenvalues in the initial pencil with ',
$ 'negative real part is ', I2 )
END
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