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来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 231 行 · 第 1/2 页

</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Based on contributions by
</span><span class="comment">*</span><span class="comment">     Bo Kagstrom and Peter Poromaa, Department of Computing Science,
</span><span class="comment">*</span><span class="comment">     Umea University, S-901 87 Umea, Sweden.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  [1] B. Kagstrom; A Direct Method for Reordering Eigenvalues in the
</span><span class="comment">*</span><span class="comment">      Generalized Real Schur Form of a Regular Matrix Pair (A, B), in
</span><span class="comment">*</span><span class="comment">      M.S. Moonen et al (eds), Linear Algebra for Large Scale and
</span><span class="comment">*</span><span class="comment">      Real-Time Applications, Kluwer Academic Publ. 1993, pp 195-218.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  [2] B. Kagstrom and P. Poromaa; Computing Eigenspaces with Specified
</span><span class="comment">*</span><span class="comment">      Eigenvalues of a Regular Matrix Pair (A, B) and Condition
</span><span class="comment">*</span><span class="comment">      Estimation: Theory, Algorithms and Software, Report
</span><span class="comment">*</span><span class="comment">      UMINF - 94.04, Department of Computing Science, Umea University,
</span><span class="comment">*</span><span class="comment">      S-901 87 Umea, Sweden, 1994. Also as LAPACK Working Note 87.
</span><span class="comment">*</span><span class="comment">      To appear in Numerical Algorithms, 1996.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  [3] B. Kagstrom and P. Poromaa, LAPACK-Style Algorithms and Software
</span><span class="comment">*</span><span class="comment">      for Solving the Generalized Sylvester Equation and Estimating the
</span><span class="comment">*</span><span class="comment">      Separation between Regular Matrix Pairs, Report UMINF - 93.23,
</span><span class="comment">*</span><span class="comment">      Department of Computing Science, Umea University, S-901 87 Umea,
</span><span class="comment">*</span><span class="comment">      Sweden, December 1993, Revised April 1994, Also as LAPACK working
</span><span class="comment">*</span><span class="comment">      Note 75. To appear in ACM Trans. on Math. Software, Vol 22, No 1,
</span><span class="comment">*</span><span class="comment">      1996.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      INTEGER            HERE
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           <a name="XERBLA.129"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>, <a name="ZTGEX2.129"></a><a href="ztgex2.f.html#ZTGEX2.1">ZTGEX2</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          MAX
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Executable Statements ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Decode and test input arguments.
</span>      INFO = 0
      IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -7
      ELSE IF( LDQ.LT.1 .OR. WANTQ .AND. ( LDQ.LT.MAX( 1, N ) ) ) THEN
         INFO = -9
      ELSE IF( LDZ.LT.1 .OR. WANTZ .AND. ( LDZ.LT.MAX( 1, N ) ) ) THEN
         INFO = -11
      ELSE IF( IFST.LT.1 .OR. IFST.GT.N ) THEN
         INFO = -12
      ELSE IF( ILST.LT.1 .OR. ILST.GT.N ) THEN
         INFO = -13
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.154"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="ZTGEXC.154"></a><a href="ztgexc.f.html#ZTGEXC.1">ZTGEXC</a>'</span>, -INFO )
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Quick return if possible
</span><span class="comment">*</span><span class="comment">
</span>      IF( N.LE.1 )
     $   RETURN
      IF( IFST.EQ.ILST )
     $   RETURN
<span class="comment">*</span><span class="comment">
</span>      IF( IFST.LT.ILST ) THEN
<span class="comment">*</span><span class="comment">
</span>         HERE = IFST
<span class="comment">*</span><span class="comment">
</span>   10    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Swap with next one below
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="ZTGEX2.173"></a><a href="ztgex2.f.html#ZTGEX2.1">ZTGEX2</a>( WANTQ, WANTZ, N, A, LDA, B, LDB, Q, LDQ, Z, LDZ,
     $                HERE, INFO )
         IF( INFO.NE.0 ) THEN
            ILST = HERE
            RETURN
         END IF
         HERE = HERE + 1
         IF( HERE.LT.ILST )
     $      GO TO 10
         HERE = HERE - 1
      ELSE
         HERE = IFST - 1
<span class="comment">*</span><span class="comment">
</span>   20    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Swap with next one above
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="ZTGEX2.190"></a><a href="ztgex2.f.html#ZTGEX2.1">ZTGEX2</a>( WANTQ, WANTZ, N, A, LDA, B, LDB, Q, LDQ, Z, LDZ,
     $                HERE, INFO )
         IF( INFO.NE.0 ) THEN
            ILST = HERE
            RETURN
         END IF
         HERE = HERE - 1
         IF( HERE.GE.ILST )
     $      GO TO 20
         HERE = HERE + 1
      END IF
      ILST = HERE
      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="ZTGEXC.204"></a><a href="ztgexc.f.html#ZTGEXC.1">ZTGEXC</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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