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<HTML>
<HEAD><TITLE>MB03FZ - SLICOT Library Routine Documentation</TITLE>
</HEAD>
<BODY>

<H2><A Name="MB03FZ">MB03FZ</A></H2>
<H3>
Eigenvalues and right deflating subspace of a complex skew-Hamiltonian/Hamiltonian pencil in factored form
</H3>
<A HREF ="#Specification"><B>[Specification]</B></A>
<A HREF ="#Arguments"><B>[Arguments]</B></A>
<A HREF ="#Method"><B>[Method]</B></A>
<A HREF ="#References"><B>[References]</B></A>
<A HREF ="#Comments"><B>[Comments]</B></A>
<A HREF ="#Example"><B>[Example]</B></A>

<P>
<B><FONT SIZE="+1">Purpose</FONT></B>
<PRE>
  To compute the eigenvalues of a complex N-by-N skew-Hamiltonian/
  Hamiltonian pencil aS - bH, with

                          (  B  F  )      (  Z11  Z12  )
    S = J Z' J' Z and H = (        ), Z = (            ),
                          (  G -B' )      (  Z21  Z22  )
                                                                (1)
        (  0  I  )
    J = (        ).
        ( -I  0  )

  The structured Schur form of the embedded real skew-Hamiltonian/
                                                         
  skew-Hamiltonian pencil, aB_S - bB_T, with B_S = J B_Z' J' B_Z,

          (  Re(Z11)  -Im(Z11)  |  Re(Z12)  -Im(Z12)  )
          (                     |                     )
          (  Im(Z11)   Re(Z11)  |  Im(Z12)   Re(Z12)  )
          (                     |                     )
    B_Z = (---------------------+---------------------) ,
          (                     |                     )
          (  Re(Z21)  -Im(Z21)  |  Re(Z22)  -Im(Z22)  )
          (                     |                     )
          (  Im(Z21)   Re(Z21)  |  Im(Z22)   Re(Z22)  )
                                                                 (2)
          ( -Im(B)  -Re(B)  | -Im(F)  -Re(F)  )
          (                 |                 )
          (  Re(B)  -Im(B)  |  Re(F)  -Im(F)  )
          (                 |                 )
    B_T = (-----------------+-----------------) ,  T = i*H,
          (                 |                 )
          ( -Im(G)  -Re(G)  | -Im(B')  Re(B') )
          (                 |                 )
          (  Re(G)  -Im(G)  | -Re(B') -Im(B') )

  is determined and used to compute the eigenvalues. Optionally, if
  COMPQ = 'C', an orthonormal basis of the right deflating subspace,
  Def_-(S, H), of the pencil aS - bH in (1), corresponding to the
  eigenvalues with strictly negative real part, is computed. Namely,
  after transforming aB_S - bB_H, in the factored form, by unitary
  matrices, we have B_Sout = J B_Zout' J' B_Zout,

             ( BA  BD  )              ( BB  BF  )
    B_Zout = (         ) and B_Hout = (         ),               (3)
             (  0  BC  )              (  0 -BB' )

  and the eigenvalues with strictly negative real part of the
  complex pencil aB_Sout - bB_Hout are moved to the top. The 
  notation M' denotes the conjugate transpose of the matrix M.
  Optionally, if COMPU = 'C', an orthonormal basis of the companion
  subspace, range(P_U) [1], which corresponds to the eigenvalues
  with negative real part, is computed. The embedding doubles the
  multiplicities of the eigenvalues of the pencil aS - bH.

</PRE>
<A name="Specification"><B><FONT SIZE="+1">Specification</FONT></B></A>
<PRE>
      SUBROUTINE MB03FZ( COMPQ, COMPU, ORTH, N, Z, LDZ, B, LDB, FG,
     $                   LDFG, NEIG, D, LDD, C, LDC, Q, LDQ, U, LDU,
     $                   ALPHAR, ALPHAI, BETA, IWORK, LIWORK, DWORK,
     $                   LDWORK, ZWORK, LZWORK, BWORK, INFO )
C     .. Scalar Arguments ..
      CHARACTER          COMPQ, COMPU, ORTH
      INTEGER            INFO, LDB, LDC, LDD, LDFG, LDQ, LDU, LDWORK,
     $                   LDZ, LIWORK, LZWORK, N, NEIG
C     .. Array Arguments ..
      LOGICAL            BWORK( * )
      INTEGER            IWORK( * )
      DOUBLE PRECISION   ALPHAI( * ), ALPHAR( * ), BETA( * ), DWORK( * )
      COMPLEX*16         B( LDB, * ), C( LDC, * ), D( LDD, * ),
     $                   FG( LDFG, * ), Q( LDQ, * ), U( LDU, * ),
     $                   Z( LDZ, * ), ZWORK( * )

</PRE>
<A name="Arguments"><B><FONT SIZE="+1">Arguments</FONT></B></A>
<P>

<B>Mode Parameters</B>
<PRE>
  COMPQ   CHARACTER*1
          Specifies whether to compute the right deflating subspace
          corresponding to the eigenvalues of aS - bH with strictly
          negative real part.
          = 'N': do not compute the deflating subspace;
          = 'C': compute the deflating subspace and store it in the
                 leading subarray of Q.

  COMPU   CHARACTER*1
          Specifies whether to compute the companion subspace
          corresponding to the eigenvalues of aS - bH with strictly
          negative real part.
          = 'N': do not compute the companion subspace;
          = 'C': compute the companion subspace and store it in the
                 leading subarray of U.

  ORTH    CHARACTER*1
          If COMPQ = 'C' or COMPU = 'C', specifies the technique for
          computing the orthonormal bases of the deflating subspace
          and companion subspace, as follows:
          = 'P':  QR factorization with column pivoting;
          = 'S':  singular value decomposition.
          If COMPQ = 'N' and COMPU = 'N', the ORTH value is not
          used.

</PRE>
<B>Input/Output Parameters</B>
<PRE>
  N       (input) INTEGER
          Order of the pencil aS - bH.  N &gt;= 0, even.

  Z       (input/output) COMPLEX*16 array, dimension (LDZ, N)
          On entry, the leading N-by-N part of this array must
          contain the non-trivial factor Z in the factorization
          S = J Z' J' Z of the skew-Hamiltonian matrix S.
          On exit, if COMPQ = 'C' or COMPU = 'C', the leading
          N-by-N part of this array contains the upper triangular
          matrix BA in (3) (see also METHOD). The strictly lower
          triangular part is not zeroed.
          If COMPQ = 'N' and COMPU = 'N', this array is unchanged
          on exit.

  LDZ     INTEGER
          The leading dimension of the array Z.  LDZ &gt;= MAX(1, N).

  B       (input/output) COMPLEX*16 array, dimension (LDB, N)
          On entry, the leading N/2-by-N/2 part of this array must
          contain the matrix B.
          On exit, if COMPQ = 'C' or COMPU = 'C', the leading
          N-by-N part of this array contains the upper triangular
          matrix BB in (3) (see also METHOD). The strictly lower
          triangular part is not zeroed. 
          If COMPQ = 'N' and COMPU = 'N', this array is unchanged
          on exit.

  LDB     INTEGER
          The leading dimension of the array B.  LDB &gt;= MAX(1, N).

  FG      (input/output) COMPLEX*16 array, dimension (LDFG, N)
          On entry, the leading N/2-by-N/2 lower triangular part of
          this array must contain the lower triangular part of the
          Hermitian matrix G, and the N/2-by-N/2 upper triangular
          part of the submatrix in the columns 2 to N/2+1 of this
          array must contain the upper triangular part of the
          Hermitian matrix F.
          On exit, if COMPQ = 'C' or COMPU = 'C', the leading
          N-by-N part of this array contains the Hermitian matrix
          BF in (3) (see also METHOD). The strictly lower triangular
          part of the input matrix is preserved. The diagonal
          elements might have tiny imaginary parts.
          If COMPQ = 'N' and COMPU = 'N', this array is unchanged
          on exit.

  LDFG    INTEGER
          The leading dimension of the array FG.  LDFG &gt;= MAX(1, N).

  NEIG    (output) INTEGER
          If COMPQ = 'C' or COMPU = 'C', the number of eigenvalues
          in aS - bH with strictly negative real part.

  D       (output) COMPLEX*16 array, dimension (LDD, N)
          If COMPQ = 'C' or COMPU = 'C', the leading N-by-N part of
          this array contains the matrix BD in (3) (see METHOD).
          If COMPQ = 'N' and COMPU = 'N', this array is not
          referenced.

  LDD     INTEGER
          The leading dimension of the array D.
          LDD &gt;= 1,         if COMPQ = 'N' and COMPU = 'N';
          LDD &gt;= MAX(1, N), if COMPQ = 'C' or  COMPU = 'C'.

  C       (output) COMPLEX*16 array, dimension (LDC, N)
          If COMPQ = 'C' or COMPU = 'C', the leading N-by-N part of
          this array contains the lower triangular matrix BC in (3)
          (see also METHOD). The strictly upper triangular part is
          not zeroed. 
          If COMPQ = 'N' and COMPU = 'N', this array is not
          referenced.

  LDC     INTEGER
          The leading dimension of the array C.
          LDC &gt;= 1,         if COMPQ = 'N' and COMPU = 'N';
          LDC &gt;= MAX(1, N), if COMPQ = 'C' or  COMPU = 'C'.

  Q       (output) COMPLEX*16 array, dimension (LDQ, 2*N)
          On exit, if COMPQ = 'C', the leading N-by-NEIG part of
          this array contains an orthonormal basis of the right
          deflating subspace corresponding to the eigenvalues of the
          pencil aS - bH with strictly negative real part.
          The remaining entries are meaningless.
          If COMPQ = 'N', this array is not referenced.

  LDQ     INTEGER
          The leading dimension of the array Q.
          LDQ &gt;= 1,           if COMPQ = 'N';
          LDQ &gt;= MAX(1, 2*N), if COMPQ = 'C'.

  U       (output) COMPLEX*16 array, dimension (LDU, 2*N)
          On exit, if COMPU = 'C', the leading N-by-NEIG part of
          this array contains an orthonormal basis of the companion
          subspace corresponding to the eigenvalues of the
          pencil aS - bH with strictly negative real part. The
          remaining entries are meaningless.
          If COMPU = 'N', this array is not referenced.

  LDU     INTEGER
          The leading dimension of the array U.
          LDU &gt;= 1,         if COMPU = 'N';
          LDU &gt;= MAX(1, N), if COMPU = 'C'.

  ALPHAR  (output) DOUBLE PRECISION array, dimension (N)
          The real parts of each scalar alpha defining an eigenvalue
          of the pencil aS - bH.

  ALPHAI  (output) DOUBLE PRECISION array, dimension (N)
          The imaginary parts of each scalar alpha defining an
          eigenvalue of the pencil aS - bH.
          If ALPHAI(j) is zero, then the j-th eigenvalue is real.

  BETA    (output) DOUBLE PRECISION array, dimension (N)
          The scalars beta that define the eigenvalues of the pencil
          aS - bH.
          Together, the quantities alpha = (ALPHAR(j),ALPHAI(j)) and
          beta = BETA(j) represent the j-th eigenvalue of the pencil
          aS - bH, in the form lambda = alpha/beta. Since lambda may
          overflow, the ratios should not, in general, be computed.

</PRE>
<B>Workspace</B>
<PRE>
  IWORK   INTEGER array, dimension (LIWORK)

  LIWORK  INTEGER
          The dimension of the array IWORK.  LIWORK &gt;= 2*N+9.

  DWORK   DOUBLE PRECISION array, dimension (LDWORK)
          On exit, if INFO = 0, DWORK(1) returns the optimal LDWORK.
          On exit, if INFO = -26, DWORK(1) returns the minimum
          value of LDWORK.

  LDWORK  INTEGER
          The dimension of the array DWORK.
          LDWORK &gt;= c*N**2 + N + MAX(6*N, 27), where
                    c = 18, if                 COMPU = 'C';
                    c = 16, if COMPQ = 'C' and COMPU = 'N';
                    c = 13, if COMPQ = 'N' and COMPU = 'N'.
          For good performance LDWORK should be generally larger.

          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.

  ZWORK   COMPLEX*16 array, dimension (LZWORK)
          On exit, if INFO = 0, ZWORK(1) returns the optimal LZWORK.
          On exit, if INFO = -28, ZWORK(1) returns the minimum
          value of LZWORK.

  LZWORK  INTEGER
          The dimension of the array ZWORK.
          LZWORK &gt;= 8*N + 28, if COMPQ = 'C';
          LZWORK &gt;= 6*N + 28, if COMPQ = 'N' and COMPU = 'C';
          LZWORK &gt;= 1,        if COMPQ = 'N' and COMPU = 'N'.
          For good performance LZWORK should be generally larger.

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

  BWORK   LOGICAL array, dimension (LBWORK)
          LBWORK &gt;= 0, if COMPQ = 'N' and COMPU = 'N';
          LBWORK &gt;= N, if COMPQ = 'C' or  COMPU = 'C'.

</PRE>
<B>Error Indicator</B>
<PRE>
  INFO    INTEGER
          = 0: succesful exit;
          &lt; 0: if INFO = -i, the i-th argument had an illegal value;
          = 1: the algorithm was not able to reveal information
               about the eigenvalues from the 2-by-2 blocks in the
               SLICOT Library routine MB03BD (called by MB04ED);
          = 2: periodic QZ iteration failed in the SLICOT Library
               routines MB03BD or MB03BZ when trying to
               triangularize the 2-by-2 blocks;
          = 3: the singular value decomposition failed in the LAPACK
               routine ZGESVD (for ORTH = 'S').

</PRE>
<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
  First T = i*H is set. Then, the embeddings, B_Z and B_T, of the
  matrices S and T, are determined and, subsequently, the SLICOT 
  Library routine MB04ED is applied to compute the structured Schur
  form, i.e., the factorizations

  ~                (  BZ11  BZ12  )
  B_Z = U' B_Z Q = (              ) and
                   (    0   BZ22  )

  ~                     (  T11  T12  )
  B_T = J Q' J' B_T Q = (            ),
                        (   0   T11' )

  where Q is real orthogonal, U is real orthogonal symplectic, BZ11,
  BZ22' are upper triangular and T11 is upper quasi-triangular.

  Second, the SLICOT Library routine MB03IZ is applied, to compute a
                 ~                                 ~
  unitary matrix Q and a unitary symplectic matrix U, such that

                ~    ~
  ~  ~   ~   (  Z11  Z12  )
  U' B_Z Q = (       ~    ) =: B_Zout,
             (   0   Z22  )

    ~        ~    ~   (  H11  H12  )
  J Q' J'(-i*B_T) Q = (            ) =: B_Hout,
                      (   0  -H11' )
       ~    ~   
  with Z11, Z22', H11 upper triangular, and such that the spectrum

           ~       ~       ~
  Spec_-(J B_Z' J' B_Z, -i*B_T) is contained in the spectrum of the
                                                ~    ~
  2*NEIG-by-2*NEIG leading principal subpencil aZ22'*Z11 - bH11.

  Finally, the right deflating subspace and the companion subspace
  are computed. See also page 21 in [1] for more details.

</PRE>
<A name="References"><B><FONT SIZE="+1">References</FONT></B></A>
<PRE>
  [1] Benner, P., Byers, R., Mehrmann, V. and Xu, H.
      Numerical Computation of Deflating Subspaces of Embedded
      Hamiltonian Pencils.
      Tech. Rep. SFB393/99-15, Technical University Chemnitz,
      Germany, June 1999.

</PRE>
<A name="Numerical Aspects"><B><FONT SIZE="+1">Numerical Aspects</FONT></B></A>
<PRE>                                                            3
  The algorithm is numerically backward stable and needs O(N )
  complex floating point operations.

</PRE>
<A name="Comments"><B><FONT SIZE="+1">Further Comments</FONT></B></A>
<PRE>
  This routine does not perform any scaling of the matrices. Scaling
  might sometimes be useful, and it should be done externally.

</PRE>

<A name="Example"><B><FONT SIZE="+1">Example</FONT></B></A>
<P>
<B>Program Text</B>
<PRE>
*     MB03FZ EXAMPLE PROGRAM TEXT
*
*     .. Parameters ..
      INTEGER            NIN, NOUT
      PARAMETER          ( NIN = 5, NOUT = 6 )
      INTEGER            NMAX
      PARAMETER          ( NMAX = 50 )
      INTEGER            LDB, LDC, LDD, LDFG, LDQ, LDU, LDWORK, LDZ,
     $                   LIWORK, LZWORK
      PARAMETER          ( LDB  = NMAX, LDC =   NMAX, LDD = NMAX,
     $                     LDFG = NMAX, LDQ = 2*NMAX, LDU = NMAX,
     $                     LDWORK = 18*NMAX*NMAX + NMAX + 3 +
     $                              MAX( 2*NMAX, 24 ), LDZ  = NMAX,
     $                     LIWORK = 2*NMAX + 9, LZWORK = 8*NMAX + 28 )
*
*     .. Local Scalars ..
      CHARACTER          COMPQ, COMPU, ORTH
      INTEGER            I, INFO, J, M, N, NEIG
*
*     .. Local Arrays ..
      COMPLEX*16         B( LDB, NMAX ), C( LDC, NMAX ), D( LDD, NMAX ),
     $                   FG( LDFG, NMAX ), Q( LDQ, 2*NMAX ),
     $                   U( LDU, 2*NMAX ), Z( LDZ, NMAX ),
     $                   ZWORK( LZWORK )
      DOUBLE PRECISION   ALPHAI( NMAX ),  ALPHAR( NMAX ), BETA( NMAX ),
     $                   DWORK( LDWORK )
      INTEGER            IWORK( LIWORK )
      LOGICAL            BWORK( NMAX )
*
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*
*     .. External Subroutines ..
      EXTERNAL           MB03FZ
*
*     .. 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 complex
*        skew-Hamiltonian/Hamiltonian pencil, corresponding to the
*        eigenvalues with strictly negative real part.
         CALL MB03FZ( COMPQ, COMPU, ORTH, N, Z, LDZ, B, LDB, FG, LDFG,
     $                NEIG, D, LDD, C, LDC, Q, LDQ, U, LDU, ALPHAR,
     $                ALPHAI, BETA, IWORK, LIWORK, DWORK, LDWORK, ZWORK,
     $                LZWORK, BWORK, 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
            IF( LSAME( COMPQ, 'C' ) .OR. LSAME( COMPU, 'C' ) ) THEN
               WRITE( NOUT, FMT = 99994 )
               DO 20 I = 1, N
                  WRITE( NOUT, FMT = 99995 ) ( D( I, J ), J = 1, N )
   20          CONTINUE
               WRITE( NOUT, FMT = 99993 )
               DO 30 I = 1, N
                  WRITE( NOUT, FMT = 99995 ) ( C( I, J ), J = 1, N )
   30          CONTINUE
               WRITE( NOUT, FMT = 99992 )
               DO 40 I = 1, N
                  WRITE( NOUT, FMT = 99995 ) ( B( I, J ), J = 1, N )
   40          CONTINUE
               WRITE( NOUT, FMT = 99991 )
               DO 50 I = 1, N
                  WRITE( NOUT, FMT = 99995 ) ( FG( I, J ), J = 1, N )
   50          CONTINUE
            END IF
            WRITE( NOUT, FMT = 99990 )
            WRITE( NOUT, FMT = 99989 ) ( ALPHAR( I ), I = 1, N )
            WRITE( NOUT, FMT = 99988 )
            WRITE( NOUT, FMT = 99989 ) ( ALPHAI( I ), I = 1, N )
            WRITE( NOUT, FMT = 99987 )
            WRITE( NOUT, FMT = 99989 ) (   BETA( I ), I = 1, N )
            IF( LSAME( COMPQ, 'C' ) .AND. NEIG.GT.0 ) THEN
               WRITE( NOUT, FMT = 99986 )
               DO 60 I = 1, N
                  WRITE( NOUT, FMT = 99995 ) ( Q( I, J ), J = 1, NEIG )
   60          CONTINUE
            END IF
            IF( LSAME( COMPU, 'C' ) .AND. NEIG.GT.0 ) THEN
               WRITE( NOUT, FMT = 99985 )
               DO 70 I = 1, N
                  WRITE( NOUT, FMT = 99995 ) ( U( I, J ), J = 1, NEIG )
   70          CONTINUE
            END IF
            IF( LSAME( COMPQ, 'C' ) .OR. LSAME( COMPU, 'C' ) )
     $         WRITE( NOUT, FMT = 99984 ) NEIG
         END IF
      END IF
      STOP
*
99999 FORMAT ( 'MB03FZ EXAMPLE PROGRAM RESULTS', 1X )
99998 FORMAT ( 'N is out of range.', /, 'N = ', I5 )
99997 FORMAT ( 'INFO on exit from MB03FZ = ', I2 )
99996 FORMAT (/'The matrix Z on exit is ' )
99995 FORMAT ( 20( 1X, F9.4, SP, F9.4, S, 'i ') )
99994 FORMAT (/'The matrix D is ' )
99993 FORMAT (/'The matrix C is ' )
99992 FORMAT (/'The matrix B on exit is ' )
99991 FORMAT (/'The matrix F on exit is ' )
99990 FORMAT (/'The vector ALPHAR is ' )
99989 FORMAT ( 50( 1X, F8.4 ) )
99988 FORMAT (/'The vector ALPHAI is ' )
99987 FORMAT (/'The vector BETA is ' )
99986 FORMAT (/'The deflating subspace corresponding to the ',
     $         'eigenvalues with negative real part is ' )
99985 FORMAT (/'The companion subspace corresponding to the ',
     $         'eigenvalues with negative real part is ' )
99984 FORMAT (/'The number of eigenvalues in the initial pencil with ',
     $         'negative real part is ', I2 )
      END
</PRE>
<B>Program Data</B>
<PRE>
MB03FZ EXAMPLE PROGRAM DATA
	C	C	P	4
   (0.0328,0.9611)   (0.6428,0.2585)   (0.7033,0.4254)   (0.2552,0.7053)
   (0.0501,0.2510)   (0.2827,0.8865)   (0.4719,0.5387)   (0.0389,0.5676)
   (0.5551,0.4242)   (0.0643,0.2716)   (0.1165,0.7875)   (0.9144,0.3891)
   (0.0539,0.7931)   (0.0408,0.2654)   (0.9912,0.0989)   (0.0991,0.6585)
   (0.0547,0.8726)   (0.4008,0.8722)
   (0.7423,0.6166)   (0.2631,0.5872)
    0.8740            0.3697           (0.9178,0.6418)
   (0.7748,0.5358)    0.1652            0.2441          
</PRE>
<B>Program Results</B>
<PRE>
MB03FZ EXAMPLE PROGRAM RESULTS

The matrix Z on exit is 
    1.1347  -0.1694i     0.0920  -0.0894i     0.5253  +0.0280i    -0.0597  +0.1098i 
    0.0000  +0.0000i    -0.9874  -0.6015i     0.2523  -0.0600i     0.3178  -0.0902i 
    0.5551  +0.4242i     0.0643  +0.2716i     0.7553  -0.3356i     0.4772  -0.3177i 
    0.0539  +0.7931i     0.0408  +0.2654i     0.9912  +0.0989i     0.9064  -0.1055i 

The matrix D is 
   -0.7634  -0.2773i    -0.8466  -0.9586i    -0.0308  -0.0175i    -0.2754  -0.0715i 
    1.2612  -0.2643i    -0.7291  -0.3165i     0.0282  -0.1748i     0.4091  +0.0233i 
    0.3773  -0.1536i    -0.3937  -0.0480i    -0.1635  +0.1617i    -0.1775  +0.1277i 
    0.7540  -0.0280i    -0.6860  -0.8306i    -0.2446  +0.0943i    -0.0722  +0.0517i 

The matrix C is 
    0.5063  +0.1548i     0.0000  +0.0000i     0.0000  +0.0000i     0.0000  +0.0000i 
   -0.0046  +0.1049i     0.3884  +0.3420i     0.0000  +0.0000i     0.0000  +0.0000i 
   -1.1206  +0.1313i    -0.2270  -0.1753i     0.4300  -0.6107i     0.0000  +0.0000i 
   -0.6127  -0.1939i    -0.5713  -0.7913i     0.3739  -0.2943i    -1.1501  -0.0850i 

The matrix B on exit is 
    0.3322  +1.9093i    -0.1216  -0.1193i    -0.0030  +0.0330i     0.0405  +0.0592i 
    0.0000  +0.0000i     0.1863  -1.8998i     0.2983  +0.2974i     0.6636  +0.5916i 
    0.0000  +0.0000i     0.0000  +0.0000i     0.4459  -0.7452i    -0.0625  +0.2197i 
    0.0000  +0.0000i     0.0000  +0.0000i     0.0000  +0.0000i     0.1418  +0.7392i 

The matrix F on exit is 
    0.0258  +0.0000i    -0.0878  +0.1090i     0.3547  +0.5306i    -0.0138  -0.8770i 
    0.7748  +0.5358i     0.0864  +0.0000i    -0.3788  -0.2829i    -0.3303  -0.0415i 
    0.0000  +0.0000i     0.0000  +0.0000i    -0.0184  +0.0000i     0.1077  -0.0795i 
    0.0000  +0.0000i     0.0000  +0.0000i     0.0000  +0.0000i    -0.0938  +0.0000i 

The vector ALPHAR is 
   0.4295  -0.4295   0.0000   0.0000

The vector ALPHAI is 
   1.5363   1.5363  -1.4069  -0.7153

The vector BETA is 
   0.5000   0.5000   1.0000   1.0000

The deflating subspace corresponding to the eigenvalues with negative real part is 
   -0.2249  +0.4158i 
   -0.1984  -0.3100i 
    0.7286  -0.0427i 
    0.3282  -0.0251i 

The companion subspace corresponding to the eigenvalues with negative real part is 
   -0.1542  -0.0712i 
   -0.4162  -0.3021i 
   -0.0806  -0.6946i 
   -0.4580  -0.0889i 

The number of eigenvalues in the initial pencil with negative real part is  1
</PRE>

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