dgegs.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 463 行 · 第 1/3 页

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</span>      ILEFT = 1
      IRIGHT = N + 1
      IWORK = IRIGHT + N
      CALL <a name="DGGBAL.295"></a><a href="dggbal.f.html#DGGBAL.1">DGGBAL</a>( <span class="string">'P'</span>, N, A, LDA, B, LDB, ILO, IHI, WORK( ILEFT ),
     $             WORK( IRIGHT ), WORK( IWORK ), IINFO )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 1
         GO TO 10
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Reduce B to triangular form, and initialize VSL and/or VSR
</span><span class="comment">*</span><span class="comment">     Workspace layout:  (&quot;work...&quot; must have at least N words)
</span><span class="comment">*</span><span class="comment">        left_permutation, right_permutation, tau, work...
</span><span class="comment">*</span><span class="comment">
</span>      IROWS = IHI + 1 - ILO
      ICOLS = N + 1 - ILO
      ITAU = IWORK
      IWORK = ITAU + IROWS
      CALL <a name="DGEQRF.310"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>( IROWS, ICOLS, B( ILO, ILO ), LDB, WORK( ITAU ),
     $             WORK( IWORK ), LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 2
         GO TO 10
      END IF
<span class="comment">*</span><span class="comment">
</span>      CALL <a name="DORMQR.319"></a><a href="dormqr.f.html#DORMQR.1">DORMQR</a>( <span class="string">'L'</span>, <span class="string">'T'</span>, IROWS, ICOLS, IROWS, B( ILO, ILO ), LDB,
     $             WORK( ITAU ), A( ILO, ILO ), LDA, WORK( IWORK ),
     $             LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 3
         GO TO 10
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( ILVSL ) THEN
         CALL <a name="DLASET.330"></a><a href="dlaset.f.html#DLASET.1">DLASET</a>( <span class="string">'Full'</span>, N, N, ZERO, ONE, VSL, LDVSL )
         CALL <a name="DLACPY.331"></a><a href="dlacpy.f.html#DLACPY.1">DLACPY</a>( <span class="string">'L'</span>, IROWS-1, IROWS-1, B( ILO+1, ILO ), LDB,
     $                VSL( ILO+1, ILO ), LDVSL )
         CALL <a name="DORGQR.333"></a><a href="dorgqr.f.html#DORGQR.1">DORGQR</a>( IROWS, IROWS, IROWS, VSL( ILO, ILO ), LDVSL,
     $                WORK( ITAU ), WORK( IWORK ), LWORK+1-IWORK,
     $                IINFO )
         IF( IINFO.GE.0 )
     $      LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 4
            GO TO 10
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( ILVSR )
     $   CALL <a name="DLASET.345"></a><a href="dlaset.f.html#DLASET.1">DLASET</a>( <span class="string">'Full'</span>, N, N, ZERO, ONE, VSR, LDVSR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Reduce to generalized Hessenberg form
</span><span class="comment">*</span><span class="comment">
</span>      CALL <a name="DGGHRD.349"></a><a href="dgghrd.f.html#DGGHRD.1">DGGHRD</a>( JOBVSL, JOBVSR, N, ILO, IHI, A, LDA, B, LDB, VSL,
     $             LDVSL, VSR, LDVSR, IINFO )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 5
         GO TO 10
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Perform QZ algorithm, computing Schur vectors if desired
</span><span class="comment">*</span><span class="comment">     Workspace layout:  (&quot;work...&quot; must have at least 1 word)
</span><span class="comment">*</span><span class="comment">        left_permutation, right_permutation, work...
</span><span class="comment">*</span><span class="comment">
</span>      IWORK = ITAU
      CALL <a name="DHGEQZ.361"></a><a href="dhgeqz.f.html#DHGEQZ.1">DHGEQZ</a>( <span class="string">'S'</span>, JOBVSL, JOBVSR, N, ILO, IHI, A, LDA, B, LDB,
     $             ALPHAR, ALPHAI, BETA, VSL, LDVSL, VSR, LDVSR,
     $             WORK( IWORK ), LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         IF( IINFO.GT.0 .AND. IINFO.LE.N ) THEN
            INFO = IINFO
         ELSE IF( IINFO.GT.N .AND. IINFO.LE.2*N ) THEN
            INFO = IINFO - N
         ELSE
            INFO = N + 6
         END IF
         GO TO 10
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Apply permutation to VSL and VSR
</span><span class="comment">*</span><span class="comment">
</span>      IF( ILVSL ) THEN
         CALL <a name="DGGBAK.380"></a><a href="dggbak.f.html#DGGBAK.1">DGGBAK</a>( <span class="string">'P'</span>, <span class="string">'L'</span>, N, ILO, IHI, WORK( ILEFT ),
     $                WORK( IRIGHT ), N, VSL, LDVSL, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 7
            GO TO 10
         END IF
      END IF
      IF( ILVSR ) THEN
         CALL <a name="DGGBAK.388"></a><a href="dggbak.f.html#DGGBAK.1">DGGBAK</a>( <span class="string">'P'</span>, <span class="string">'R'</span>, N, ILO, IHI, WORK( ILEFT ),
     $                WORK( IRIGHT ), N, VSR, LDVSR, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 8
            GO TO 10
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Undo scaling
</span><span class="comment">*</span><span class="comment">
</span>      IF( ILASCL ) THEN
         CALL <a name="DLASCL.399"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'H'</span>, -1, -1, ANRMTO, ANRM, N, N, A, LDA, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
         CALL <a name="DLASCL.404"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, -1, -1, ANRMTO, ANRM, N, 1, ALPHAR, N,
     $                IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
         CALL <a name="DLASCL.410"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, -1, -1, ANRMTO, ANRM, N, 1, ALPHAI, N,
     $                IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( ILBSCL ) THEN
         CALL <a name="DLASCL.419"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'U'</span>, -1, -1, BNRMTO, BNRM, N, N, B, LDB, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
         CALL <a name="DLASCL.424"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, -1, -1, BNRMTO, BNRM, N, 1, BETA, N, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>   10 CONTINUE
      WORK( 1 ) = LWKOPT
<span class="comment">*</span><span class="comment">
</span>      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="DGEGS.436"></a><a href="dgegs.f.html#DGEGS.1">DGEGS</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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