## MB03ZD

### Computing the stable and unstable invariant subspaces for a Hamiltonian matrix with no eigenvalues on the imaginary axis

[Specification] [Arguments] [Method] [References] [Comments] [Example]

Purpose

      To compute the stable and unstable invariant subspaces for a
      Hamiltonian matrix with no eigenvalues on the imaginary axis,
      using the output of the SLICOT Library routine MB03XD.

Specification

          SUBROUTINE MB03ZD( WHICH, METH, STAB, BALANC, ORTBAL, SELECT, N,
         $                   MM, ILO, SCALE, S, LDS, T, LDT, G, LDG, U1,
         $                   LDU1, U2, LDU2, V1, LDV1, V2, LDV2, M, WR, WI,
         $                   US, LDUS, UU, LDUU, LWORK, IWORK, DWORK,
         $                   LDWORK, INFO )
    C     .. Scalar Arguments ..
          CHARACTER         BALANC, METH, ORTBAL, STAB, WHICH
          INTEGER           ILO, INFO, LDG, LDS, LDT, LDU1, LDU2, LDUS,
         $                  LDUU, LDV1, LDV2, LDWORK, M, MM, N
    C     .. Array Arguments ..
          LOGICAL           LWORK(*), SELECT(*)
          INTEGER           IWORK(*)
          DOUBLE PRECISION  DWORK(*), G(LDG,*), S(LDS,*), SCALE(*),
         $                  T(LDT,*), U1(LDU1,*), U2(LDU2,*), US(LDUS,*),
         $                  UU(LDUU,*), V1(LDV1,*), V2(LDV2,*), WI(*),
         $                  WR(*)

Arguments

Mode Parameters

      WHICH   CHARACTER*1
              Specifies the cluster of eigenvalues for which the
              invariant subspaces are computed:
              = 'A':  select all n eigenvalues;
              = 'S':  select a cluster of eigenvalues specified by
                      SELECT.

      METH    CHARACTER*1
              If WHICH = 'A' this parameter specifies the method to be
              used for computing bases of the invariant subspaces:
              = 'S':  compute the n-dimensional basis from a set of
                      n vectors;
              = 'L':  compute the n-dimensional basis from a set of
                      2*n vectors;
              = 'Q':  quick return of the set of n vectors;
              = 'R':  quick return of the set of 2*n vectors.
              When in doubt, use METH = 'S'. In some cases, METH = 'L'
              may result in more accurately computed invariant
              subspaces, see [1].
              Options METH = 'Q' or METH = 'R' return the range vectors
              Y = [ Y1; Y2 ], where Y1 and Y2 have 2*n rows and n or 2*n
              columns, respectively, which can be directly used, e.g.,
              for finding the (stabilizing) solution of a Riccati
              equation, by solving X*Y1 = Y2. Note that Y1 might be
              singular when METH = 'Q'.

      STAB    CHARACTER*1
              Specifies the type of invariant subspaces to be computed:
              = 'S':  compute the stable invariant subspace, i.e., the
                      invariant subspace belonging to those selected
                      eigenvalues that have negative real part;
              = 'U':  compute the unstable invariant subspace, i.e.,
                      the invariant subspace belonging to those
                      selected eigenvalues that have positive real
                      part;
              = 'B':  compute both the stable and unstable invariant
                      subspaces.

      BALANC  CHARACTER*1
              Specifies the type of inverse balancing transformation
              required:
              = 'N':  do nothing;
              = 'P':  do inverse transformation for permutation only;
              = 'S':  do inverse transformation for scaling only;
              = 'B':  do inverse transformations for both permutation
                      and scaling.
              BALANC must be the same as the argument BALANC supplied to
              MB03XD. Note that if the data is further post-processed,
              e.g., for solving an algebraic Riccati equation, it is
              recommended to delay inverse balancing (in particular the
              scaling part) and apply it to the final result only,
              see [2]. Inverse balancing is not used by this routine
              if METH = 'Q' or METH = 'R'.

      ORTBAL  CHARACTER*1
              If BALANC <> 'N', this option specifies how inverse
              balancing is applied to the computed invariant subspaces:
              = 'B':  apply inverse balancing before orthogonal bases
                      for the invariant subspaces are computed;
              = 'A':  apply inverse balancing after orthogonal bases
                      for the invariant subspaces have been computed;
                      this may yield non-orthogonal bases if
                      BALANC = 'S' or BALANC = 'B'.

      SELECT  (input) LOGICAL array, dimension (N)
              If WHICH = 'S', SELECT specifies the eigenvalues
              corresponding to the positive and negative square
              roots of the eigenvalues of S*T in the selected cluster.
              To select a real eigenvalue w(j), SELECT(j) must be set
              to .TRUE.. To select a complex conjugate pair of
              eigenvalues w(j) and w(j+1), corresponding to a 2-by-2
              diagonal block, both SELECT(j) and SELECT(j+1) must be set
              to .TRUE.; a complex conjugate pair of eigenvalues must be
              either both included in the cluster or both excluded.
              This array is not referenced if WHICH = 'A'.

Input/Output Parameters

      N       (input) INTEGER
              The order of the matrices S, T and G. N >= 0.

      MM      (input) INTEGER
              The number of columns in the arrays US and/or UU.
              If WHICH = 'A' and (METH = 'S' or METH = 'Q'),  MM =   N;
              if WHICH = 'A' and (METH = 'L' or METH = 'R'),  MM = 2*N;
              if WHICH = 'S',                                 MM =   M.
              The values above for MM give the numbers of vectors to be
              returned, if METH = 'Q' or METH = 'R', or the numbers of
              vectors to be used for computing a basis for the invariant
              subspace(s), if METH = 'S' or METH = 'L', or WHICH = 'S'.

      ILO     (input) INTEGER
              If BALANC <> 'N', then ILO is the integer returned by
              MB03XD.  1 <= ILO <= N+1.

      SCALE   (input) DOUBLE PRECISION array, dimension (N)
              If BALANC <> 'N', the leading N elements of this array
              must contain details of the permutation and scaling
              factors, as returned by MB03XD.
              This array is not referenced if BALANC = 'N'.

      S       (input/output) DOUBLE PRECISION array, dimension (LDS,N)
              On entry, the leading N-by-N part of this array must
              contain the matrix S in real Schur form.
              On exit, the leading N-by-N part of this array is
              overwritten.

      LDS     INTEGER
              The leading dimension of the array S.  LDS >= max(1,N).

      T       (input/output) DOUBLE PRECISION array, dimension (LDT,N)
              On entry, the leading N-by-N part of this array must
              contain the upper triangular matrix T.
              On exit, the leading N-by-N part of this array is
              overwritten.

      LDT     INTEGER
              The leading dimension of the array T.  LDT >= max(1,N).

      G       (input/output) DOUBLE PRECISION array, dimension (LDG,N)
              On entry, if METH = 'L' or METH = 'R', the leading N-by-N
              part of this array must contain a general matrix G.
              On exit, if METH = 'L' or METH = 'R', the leading N-by-N
              part of this array is overwritten.
              This array is not referenced if METH = 'S' or METH = 'Q'.

      LDG     INTEGER
              The leading dimension of the array G.  LDG >= 1.
              LDG >= max(1,N) if METH = 'L' or METH = 'R'.

      U1      (input/output) DOUBLE PRECISION array, dimension (LDU1,N)
              On entry, the leading N-by-N part of this array must
              contain the (1,1) block of an orthogonal symplectic
              matrix U.
              On exit, this array is overwritten.

      LDU1    INTEGER
              The leading dimension of the array U1.  LDU1 >= MAX(1,N).

      U2      (input/output) DOUBLE PRECISION array, dimension (LDU2,N)
              On entry, the leading N-by-N part of this array must
              contain the (2,1) block of an orthogonal symplectic
              matrix U.
              On exit, this array is overwritten.

      LDU2    INTEGER
              The leading dimension of the array U2.  LDU2 >= MAX(1,N).

      V1      (input/output) DOUBLE PRECISION array, dimension (LDV1,N)
              On entry, the leading N-by-N part of this array must
              contain the (1,1) block of an orthogonal symplectic
              matrix V.
              On exit, this array is overwritten.

      LDV1    INTEGER
              The leading dimension of the array V1.  LDV1 >= MAX(1,N).

      V2      (input/output) DOUBLE PRECISION array, dimension (LDV1,N)
              On entry, the leading N-by-N part of this array must
              contain the (2,1) block of an orthogonal symplectic
              matrix V.
              On exit, this array is overwritten.

      LDV2    INTEGER
              The leading dimension of the array V2.  LDV2 >= MAX(1,N).

      M       (output) INTEGER
              The number of selected eigenvalues.

      WR      (output) DOUBLE PRECISION array, dimension (M)
      WI      (output) DOUBLE PRECISION array, dimension (M)
              On exit, the leading M elements of WR and WI contain the
              real and imaginary parts, respectively, of the selected
              eigenvalues that have nonpositive real part. Complex
              conjugate pairs of eigenvalues with real part not equal
              to zero will appear consecutively with the eigenvalue
              having the positive imaginary part first. Note that, due
              to roundoff errors, these numbers may differ from the
              eigenvalues computed by MB03XD.

      US      (output) DOUBLE PRECISION array, dimension (LDUS,MM)
              On exit, if STAB = 'S' or STAB = 'B', the leading
              2*N-by-MM part of this array contains a basis for the
              stable invariant subspace belonging to the selected
              eigenvalues, if METH = 'S' or METH = 'L', or the range
              vectors Y, if METH = 'Q' or METH = 'R' (see parameter
              METH). This basis is orthogonal unless ORTBAL = 'A'.

      LDUS    INTEGER
              The leading dimension of the array US.  LDUS >= 1.
              If STAB = 'S' or STAB = 'B',  LDUS >= 2*N.

      UU      (output) DOUBLE PRECISION array, dimension (LDUU,MM)
              On exit, if STAB = 'U' or STAB = 'B', the leading
              2*N-by-MM part of this array contains a basis for the
              unstable invariant subspace belonging to the selected
              eigenvalues, if METH = 'S' or METH = 'L', or the range
              vectors Y, if METH = 'Q' or METH = 'R' (see parameter
              METH). This basis is orthogonal unless ORTBAL = 'A'.

      LDUU    INTEGER
              The leading dimension of the array UU.  LDUU >= 1.
              If STAB = 'U' or STAB = 'B',  LDUU >= 2*N.

Workspace

      LWORK   LOGICAL array, dimension (2*N)
              This array is only referenced if WHICH = 'A' and
              (METH = 'L' or METH = 'R').

      IWORK   INTEGER array, dimension (LIWORK)
              LIWORK = 2*N, if WHICH = 'A' and METH = 'L';
              LIWORK = N,   if WHICH = 'A' and METH = 'S';
              LIWORK = 0,   if WHICH = 'A' and METH = 'Q' or METH = 'R';
              LIWORK = M,   if WHICH = 'S'.

      DWORK   DOUBLE PRECISION array, dimension (LDWORK)
              On exit, if INFO = 0,  DWORK(1)  returns the optimal
              value of LDWORK.
              On exit, if  INFO = -35,  DWORK(1)  returns the minimum
              value of LDWORK.

      LDWORK  INTEGER
              The length of the array DWORK.
              If WHICH = 'S' or METH = 'S' or METH = 'Q':
                 LDWORK >= MAX( 1, 4*M*M + MAX( 8*M, 4*N ) ).
              If WHICH = 'A' and (METH = 'L' or METH = 'R') and
                 ( STAB = 'U' or STAB = 'S' ):
                 LDWORK >= MAX( 1, 2*N*N + 2*N, 8*N ).
              If WHICH = 'A' and (METH = 'L' or METH = 'R') and
                 STAB = 'B':
                 LDWORK >= 8*N + 1.

              If LDWORK = -1, then a workspace query is assumed;
              the routine only calculates the optimal size of the
              DWORK array, returns this value as the first entry of
              the DWORK array, and no error message related to LDWORK
              is issued by XERBLA.

Error Indicator

      INFO    INTEGER
              = 0:  successful exit;
              < 0:  if INFO = -i, the i-th argument had an illegal
                    value;
              = 1:  some of the selected eigenvalues are on or too close
                    to the imaginary axis;
              = 2:  reordering of the product S*T in routine MB03ZA
                    failed because some eigenvalues are too close to
                    separate;
              = 3:  the QR algorithm failed to compute some Schur form
                    in MB03ZA;
              = 4:  reordering of the Hamiltonian Schur form in routine
                    MB03TD failed because some eigenvalues are too close
                    to separate;
              = 5:  the computed stable invariant subspace for
                    METH = 'S' is inaccurate. This may be taken as a
                    warning and a suggestion to try METH = 'L';
              = 6:  the computed unstable invariant subspace for
                    METH = 'S' is inaccurate. This may be taken as a
                    warning and a suggestion to try METH = 'L'.

Method

      This is an implementation of Algorithm 1 in [1].

Numerical Aspects

      The method is strongly backward stable for an embedded
      (skew-)Hamiltonian matrix, see [1]. Although good results have
      been reported if the eigenvalues are not too close to the
      imaginary axis, the method is not backward stable for the original
      Hamiltonian matrix itself.

References

      [1] Benner, P., Mehrmann, V., and Xu, H.
          A new method for computing the stable invariant subspace of a
          real Hamiltonian matrix, J. Comput. Appl. Math., 86,
          pp. 17-43, 1997.

      [2] Benner, P.
          Symplectic balancing of Hamiltonian matrices.
          SIAM J. Sci. Comput., 22 (5), pp. 1885-1904, 2001.

Further Comments

      None

Example

Program Text

    *     MB03ZD EXAMPLE PROGRAM TEXT
    *
    *     .. Parameters ..
          DOUBLE PRECISION ZERO, ONE
          PARAMETER        ( ZERO = 0.0D0, ONE = 1.0D0 )
          INTEGER          NIN, NOUT
          PARAMETER        ( NIN = 5, NOUT = 6 )
          INTEGER          NMAX
          PARAMETER        ( NMAX = 200 )
          INTEGER          LDG, LDRES, LDS, LDT, LDU1, LDU2, LDUS, LDUU,
         $                 LDV1, LDV2, LDWORK
          PARAMETER        ( LDG = NMAX, LDRES = 2*NMAX, LDS = NMAX,
         $                   LDT = NMAX, LDU1 = NMAX, LDU2 = NMAX,
         $                   LDUS = 2*NMAX, LDUU = 2*NMAX, LDV1 = NMAX,
         $                   LDV2 = NMAX, LDWORK = 3*NMAX*NMAX + 7*NMAX )
    *     .. Local Scalars ..
          CHARACTER*1      BALANC, METH, ORTBAL, STAB, WHICH
          INTEGER          I, ILO, INFO, J, M, N
    *     .. Local Arrays ..
          LOGICAL          LWORK(2*NMAX), SELECT(NMAX)
          INTEGER          IWORK(2*NMAX)
          DOUBLE PRECISION DWORK(LDWORK), G(LDG, NMAX), RES(LDRES,NMAX),
         $                 S(LDS, NMAX), SCALE(NMAX), T(LDT,NMAX),
         $                 U1(LDU1,NMAX), U2(LDU2, NMAX), US(LDUS,2*NMAX),
         $                 UU(LDUU,2*NMAX), V1(LDV1,NMAX), V2(LDV2, NMAX),
         $                 WI(NMAX), WR(NMAX)
    *     .. External Functions ..
          EXTERNAL         DLANGE, LSAME
          LOGICAL          LSAME
          DOUBLE PRECISION DLANGE
    *     .. External Subroutines ..
          EXTERNAL         MB03ZD
    *     .. Executable Statements ..
          WRITE ( NOUT, FMT = 99999 )
    *     Skip the heading in the data file and read the data.
          READ ( NIN, FMT = '()' )
          READ ( NIN, FMT = * )  N, ILO, WHICH, METH, STAB, BALANC, ORTBAL
          IF ( N.LE.0 .OR. N.GT.NMAX ) THEN
             WRITE ( NOUT, FMT = 99992 ) N
          ELSE
    *
             IF ( LSAME( WHICH, 'S' ) )
         $      READ ( NIN, FMT = * ) ( SELECT(I), I = 1,N )
             READ ( NIN, FMT = * ) ( ( S(I,J), J = 1,N ), I = 1,N )
             READ ( NIN, FMT = * ) ( ( T(I,J), J = 1,N ), I = 1,N )
             IF ( LSAME( WHICH, 'A' ).AND.LSAME( METH, 'L' ) )
         $      READ ( NIN, FMT = * ) ( ( G(I,J), J = 1,N ), I = 1,N )
             IF ( LSAME( BALANC, 'P' ).OR.LSAME( BALANC, 'S' ).OR.
         $        LSAME( BALANC, 'B' ) )
         $      READ ( NIN, FMT = * ) ( SCALE(I), I = 1,N )
             READ ( NIN, FMT = * ) ( ( U1(I,J), J = 1,N ), I = 1,N )
             READ ( NIN, FMT = * ) ( ( U2(I,J), J = 1,N ), I = 1,N )
             READ ( NIN, FMT = * ) ( ( V1(I,J), J = 1,N ), I = 1,N )
             READ ( NIN, FMT = * ) ( ( V2(I,J), J = 1,N ), I = 1,N )
    *
             CALL MB03ZD( WHICH, METH, STAB, BALANC, ORTBAL, SELECT, N, 2*N,
         $                ILO, SCALE, S, LDS, T, LDT, G, LDG, U1, LDU1, U2,
         $                LDU2, V1, LDV1, V2, LDV2, M, WR, WI, US, LDUS,
         $                UU, LDUU, LWORK, IWORK, DWORK, LDWORK, INFO )
    *
             IF ( INFO.NE.0 ) THEN
                WRITE ( NOUT, FMT = 99998 ) INFO
             ELSE
                WRITE ( NOUT, FMT = 99997 )
                DO 20  I = 1, N
                   WRITE ( NOUT, FMT = 99996 ) I, WR(I), WI(I)
    20          CONTINUE
    *
                IF ( LSAME( STAB, 'S' ).OR.LSAME( STAB, 'B' ) ) THEN
                   WRITE ( NOUT, FMT = 99995 )
                   DO 30  I = 1, 2*N
                      WRITE ( NOUT, FMT = 99993 ) ( US(I,J), J = 1,M )
    30             CONTINUE
                   IF ( LSAME( ORTBAL, 'B' ).OR.LSAME( BALANC, 'N' ).OR.
         $            LSAME( BALANC, 'P' ) ) THEN
                      CALL DGEMM( 'Transpose', 'No Transpose', M, M, 2*N,
         $                        ONE, US, LDUS, US, LDUS, ZERO, RES,
         $                        LDRES )
                      DO 40  I = 1, M
                         RES(I,I) = RES(I,I) - ONE
    40                CONTINUE
                      WRITE ( NOUT, FMT = 99991 ) DLANGE( 'Frobenius', M, M,
         $                    RES, LDRES, DWORK )
                   END IF
                   CALL DGEMM( 'Transpose', 'No Transpose', M, M, N, ONE,
         $                     US, LDUS, US(N+1,1), LDUS, ZERO, RES, LDRES )
                   CALL DGEMM( 'Transpose', 'No Transpose', M, M, N, -ONE,
         $                     US(N+1,1), LDUS, US, LDUS, ONE, RES, LDRES )
                   WRITE ( NOUT, FMT = 99990 ) DLANGE( 'Frobenius', M, M,
         $                 RES, LDRES, DWORK )
                END IF
    *
                IF ( LSAME( STAB, 'U' ).OR.LSAME( STAB, 'B' ) ) THEN
                   WRITE ( NOUT, FMT = 99994 )
                   DO 50  I = 1, 2*N
                      WRITE ( NOUT, FMT = 99993 ) ( UU(I,J), J = 1,M )
    50             CONTINUE
                   IF ( LSAME( ORTBAL, 'B' ).OR.LSAME( BALANC, 'N' ).OR.
         $            LSAME( BALANC, 'P' ) ) THEN
                      CALL DGEMM( 'Transpose', 'No Transpose', M, M, 2*N,
         $                        ONE, UU, LDUU, UU, LDUU, ZERO, RES,
         $                        LDRES )
                      DO 60  I = 1, M
                         RES(I,I) = RES(I,I) - ONE
    60                CONTINUE
                      WRITE ( NOUT, FMT = 99989 ) DLANGE( 'Frobenius', M, M,
         $                    RES, LDRES, DWORK )
                   END IF
                   CALL DGEMM( 'Transpose', 'No Transpose', M, M, N, ONE,
         $                     UU, LDUU, UU(N+1,1), LDUU, ZERO, RES, LDRES )
                   CALL DGEMM( 'Transpose', 'No Transpose', M, M, N, -ONE,
         $                     UU(N+1,1), LDUU, UU, LDUU, ONE, RES, LDRES )
                   WRITE ( NOUT, FMT = 99988 ) DLANGE( 'Frobenius', M, M,
         $                 RES, LDRES, DWORK )
                END IF
             END IF
          END IF
    *
    99999 FORMAT (' MB03ZD EXAMPLE PROGRAM RESULTS',/1X)
    99998 FORMAT (' INFO on exit from MB03ZD = ',I2)
    99997 FORMAT (' The stable eigenvalues are',//'   i',6X,
         $        'WR(i)',6X,'WI(i)',/)
    99996 FORMAT (I4,3X,F8.4,3X,F8.4)
    99995 FORMAT (/' A basis for the stable invariant subspace is')
    99994 FORMAT (/' A basis for the unstable invariant subspace is')
    99993 FORMAT (20(1X,F9.3))
    99992 FORMAT (/' N is out of range.',/' N = ',I5)
    99991 FORMAT (/' Orthogonality of US: || US''*US - I ||_F = ',G7.2)
    99990 FORMAT (/' Symplecticity of US: || US''*J*US   ||_F = ',G7.2)
    99989 FORMAT (/' Orthogonality of UU: || UU''*UU - I ||_F = ',G7.2)
    99988 FORMAT (/' Symplecticity of UU: || UU''*J*UU   ||_F = ',G7.2)

          END

Program Data

    MB03ZD EXAMPLE PROGRAM DATA
    	5	1	A	L	B	N	B
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      0.0000000000000000 -0.1386140422054264 -0.3006779624777515  0.2944143257134196  0.3456440339120323
      0.0000000000000000  0.0000000000000000  0.0000000000000000 -0.2710128384740570  0.0933189808067138
      0.0000000000000000  0.0000000000000000  0.0000000000000000  0.4844146572359603  0.2004347508746697
      3.2038208121776366  0.1805955192510651  0.2466389119377561 -0.2539149302433368 -0.0359238844381195
      0.0000000000000000 -0.7196686433290816  0.0000000000000000  0.2428659121580384 -0.0594190100670832
      0.0000000000000000  0.0000000000000000 -0.1891741194498107 -0.3309578443491266 -0.0303520731950515
      0.0000000000000000  0.0000000000000000  0.0000000000000000 -0.4361574461961550  0.0000000000000000
      0.0000000000000000  0.0000000000000000  0.0000000000000000  0.0000000000000000  0.1530894573304220
     -0.0370982242678464  0.0917788436945724 -0.0560402416315252  0.1345152517579192  0.0256668227276700
      0.0652183678916931 -0.0700457231988297  0.0350041175858839 -0.2233868768749268 -0.1171980260782843
     -0.0626428681377119  0.2327575351902772 -0.1251515732208170 -0.0177816046663201  0.3696921118421182
      0.0746042309265599 -0.0828007611045140  0.0217427473546043 -0.1157775118548851 -0.3161183681200527
      0.1374372236164812  0.1002727885506992  0.4021556774753973 -0.0431072263235579  0.1067394572547867
      0.3806883009357247 -0.0347810363019649 -0.5014665065895758  0.5389691288472394  0.2685446895251367
      0.4642712665555326 -0.5942766860716395  0.4781179763952615  0.2334370556238151  0.0166790369048933
      0.2772789197782788 -0.0130145392695876 -0.2123817030594055 -0.2550292626960107 -0.5049268366774490
      0.4209268575081796  0.1499593172661228 -0.1925590746592156 -0.5472292877802402  0.4543329704184054
      0.3969669479129449  0.6321903535930828  0.3329156356041961  0.0163533225344433 -0.2638879466190024
     -0.1795922007470742  0.1908329820840911  0.0868799433942070  0.3114741142062388 -0.2579907627915167
     -0.2447897730222852 -0.1028403314750045 -0.1157840914576285 -0.1873268885694406  0.1700708002861580
     -0.2243335325285328  0.3180998613802520  0.3315380214794822  0.1977859924739963  0.5072476567310013
     -0.2128397588651423 -0.2740560593051881  0.1941418870268881 -0.3096684962457369 -0.0581576193198714
     -0.2002027567371932 -0.0040094115506855 -0.3979373387545264  0.1520881534833910 -0.2010804514091372
      0.4447147692018334 -0.6830166755147440 -0.0002576861753487  0.5781954611783305 -0.0375091627893805
      0.5121756358795817  0.0297197140254773  0.4332229148788766 -0.3240527006890552  0.5330850295256511
      0.3664711365265602  0.3288511296455119  0.0588396016404451  0.1134221597062257  0.1047567336850078
      0.4535357098437908  0.1062866148880792 -0.3964092656837774 -0.2211800890450674  0.0350667323996222
      0.4450432900616097  0.2950206358263853 -0.1617837757183893 -0.0376369332204927 -0.6746752660482623
      0.0000000000000000  0.0000000000000000  0.0000000000000000  0.0000000000000000  0.0000000000000000
      0.0299719306696789 -0.2322624725320701 -0.0280846899680325 -0.3044255686880000 -0.1077641482535519
     -0.0069083614679702  0.3351358347080056 -0.4922707032978891  0.4293545450291714  0.4372821269062001
      0.0167847133528843  0.2843629278945327  0.5958979805231146  0.3097336757510886 -0.2086733033047188
      0.0248567764822071 -0.2810759958040470 -0.1653113624869834 -0.3528780198620412 -0.0254898556119252

Program Results

    MB03ZD EXAMPLE PROGRAM RESULTS

    The stable eigenvalues are

      i      WR(i)      WI(i)

      1    -3.1941     0.0000
      2    -0.1350     0.3179
      3    -0.1350    -0.3179
      4    -0.0595     0.2793
      5    -0.0595    -0.2793

    A basis for the stable invariant subspace is
       -0.102    -0.116     0.627     0.118    -0.605
       -0.100    -0.510    -0.266     0.504     0.124
       -0.179     0.015    -0.112    -0.142     0.413
       -0.055     0.252     0.182    -0.134     0.100
       -0.078     0.576    -0.271    -0.252    -0.177
        0.340    -0.135     0.053    -0.234    -0.110
        0.528     0.108    -0.205     0.219    -0.096
        0.397    -0.429     0.161    -0.598     0.199
        0.444     0.342     0.447     0.406     0.440
        0.434     0.014    -0.383     0.072    -0.391

    Orthogonality of US: || US'*US - I ||_F = .62E-15

    Symplecticity of US: || US'*J*US   ||_F = .23E-14

    A basis for the unstable invariant subspace is
       -0.428     0.383     0.048     0.105     0.187
       -0.506    -0.100     0.541     0.245     0.223
       -0.334    -0.524    -0.044    -0.153     0.126
       -0.453     0.076     0.103    -0.525    -0.268
       -0.436     0.098    -0.752     0.209    -0.251
       -0.093    -0.089     0.258    -0.114    -0.725
       -0.112    -0.196    -0.186    -0.302     0.394
       -0.120    -0.286     0.027     0.680    -0.119
       -0.102     0.630     0.079     0.040     0.127
       -0.091    -0.171    -0.136    -0.136     0.231

    Orthogonality of UU: || UU'*UU - I ||_F = .69E-15

    Symplecticity of UU: || UU'*J*UU   ||_F = .10E-13

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