cgeev.f.html

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</span><span class="comment">*</span><span class="comment">        Perform QR iteration, accumulating Schur vectors in VL
</span><span class="comment">*</span><span class="comment">        (CWorkspace: need 1, prefer HSWORK (see comments) )
</span><span class="comment">*</span><span class="comment">        (RWorkspace: none)
</span><span class="comment">*</span><span class="comment">
</span>         IWRK = ITAU
         CALL <a name="CHSEQR.269"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>( <span class="string">'S'</span>, <span class="string">'V'</span>, N, ILO, IHI, A, LDA, W, VL, LDVL,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
<span class="comment">*</span><span class="comment">
</span>         IF( WANTVR ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Want left and right eigenvectors
</span><span class="comment">*</span><span class="comment">           Copy Schur vectors to VR
</span><span class="comment">*</span><span class="comment">
</span>            SIDE = <span class="string">'B'</span>
            CALL <a name="CLACPY.278"></a><a href="clacpy.f.html#CLACPY.1">CLACPY</a>( <span class="string">'F'</span>, N, N, VL, LDVL, VR, LDVR )
         END IF
<span class="comment">*</span><span class="comment">
</span>      ELSE IF( WANTVR ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Want right eigenvectors
</span><span class="comment">*</span><span class="comment">        Copy Householder vectors to VR
</span><span class="comment">*</span><span class="comment">
</span>         SIDE = <span class="string">'R'</span>
         CALL <a name="CLACPY.287"></a><a href="clacpy.f.html#CLACPY.1">CLACPY</a>( <span class="string">'L'</span>, N, N, A, LDA, VR, LDVR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Generate unitary matrix in VR
</span><span class="comment">*</span><span class="comment">        (CWorkspace: need 2*N-1, prefer N+(N-1)*NB)
</span><span class="comment">*</span><span class="comment">        (RWorkspace: none)
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="CUNGHR.293"></a><a href="cunghr.f.html#CUNGHR.1">CUNGHR</a>( N, ILO, IHI, VR, LDVR, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Perform QR iteration, accumulating Schur vectors in VR
</span><span class="comment">*</span><span class="comment">        (CWorkspace: need 1, prefer HSWORK (see comments) )
</span><span class="comment">*</span><span class="comment">        (RWorkspace: none)
</span><span class="comment">*</span><span class="comment">
</span>         IWRK = ITAU
         CALL <a name="CHSEQR.301"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>( <span class="string">'S'</span>, <span class="string">'V'</span>, N, ILO, IHI, A, LDA, W, VR, LDVR,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
<span class="comment">*</span><span class="comment">
</span>      ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Compute eigenvalues only
</span><span class="comment">*</span><span class="comment">        (CWorkspace: need 1, prefer HSWORK (see comments) )
</span><span class="comment">*</span><span class="comment">        (RWorkspace: none)
</span><span class="comment">*</span><span class="comment">
</span>         IWRK = ITAU
         CALL <a name="CHSEQR.311"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>( <span class="string">'E'</span>, <span class="string">'N'</span>, N, ILO, IHI, A, LDA, W, VR, LDVR,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     If INFO &gt; 0 from <a name="CHSEQR.315"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>, then quit
</span><span class="comment">*</span><span class="comment">
</span>      IF( INFO.GT.0 )
     $   GO TO 50
<span class="comment">*</span><span class="comment">
</span>      IF( WANTVL .OR. WANTVR ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Compute left and/or right eigenvectors
</span><span class="comment">*</span><span class="comment">        (CWorkspace: need 2*N)
</span><span class="comment">*</span><span class="comment">        (RWorkspace: need 2*N)
</span><span class="comment">*</span><span class="comment">
</span>         IRWORK = IBAL + N
         CALL <a name="CTREVC.327"></a><a href="ctrevc.f.html#CTREVC.1">CTREVC</a>( SIDE, <span class="string">'B'</span>, SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
     $                N, NOUT, WORK( IWRK ), RWORK( IRWORK ), IERR )
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( WANTVL ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Undo balancing of left eigenvectors
</span><span class="comment">*</span><span class="comment">        (CWorkspace: none)
</span><span class="comment">*</span><span class="comment">        (RWorkspace: need N)
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="CGEBAK.337"></a><a href="cgebak.f.html#CGEBAK.1">CGEBAK</a>( <span class="string">'B'</span>, <span class="string">'L'</span>, N, ILO, IHI, RWORK( IBAL ), N, VL, LDVL,
     $                IERR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Normalize left eigenvectors and make largest component real
</span><span class="comment">*</span><span class="comment">
</span>         DO 20 I = 1, N
            SCL = ONE / SCNRM2( N, VL( 1, I ), 1 )
            CALL CSSCAL( N, SCL, VL( 1, I ), 1 )
            DO 10 K = 1, N
               RWORK( IRWORK+K-1 ) = REAL( VL( K, I ) )**2 +
     $                               AIMAG( VL( K, I ) )**2
   10       CONTINUE
            K = ISAMAX( N, RWORK( IRWORK ), 1 )
            TMP = CONJG( VL( K, I ) ) / SQRT( RWORK( IRWORK+K-1 ) )
            CALL CSCAL( N, TMP, VL( 1, I ), 1 )
            VL( K, I ) = CMPLX( REAL( VL( K, I ) ), ZERO )
   20    CONTINUE
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( WANTVR ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Undo balancing of right eigenvectors
</span><span class="comment">*</span><span class="comment">        (CWorkspace: none)
</span><span class="comment">*</span><span class="comment">        (RWorkspace: need N)
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="CGEBAK.362"></a><a href="cgebak.f.html#CGEBAK.1">CGEBAK</a>( <span class="string">'B'</span>, <span class="string">'R'</span>, N, ILO, IHI, RWORK( IBAL ), N, VR, LDVR,
     $                IERR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Normalize right eigenvectors and make largest component real
</span><span class="comment">*</span><span class="comment">
</span>         DO 40 I = 1, N
            SCL = ONE / SCNRM2( N, VR( 1, I ), 1 )
            CALL CSSCAL( N, SCL, VR( 1, I ), 1 )
            DO 30 K = 1, N
               RWORK( IRWORK+K-1 ) = REAL( VR( K, I ) )**2 +
     $                               AIMAG( VR( K, I ) )**2
   30       CONTINUE
            K = ISAMAX( N, RWORK( IRWORK ), 1 )
            TMP = CONJG( VR( K, I ) ) / SQRT( RWORK( IRWORK+K-1 ) )
            CALL CSCAL( N, TMP, VR( 1, I ), 1 )
            VR( K, I ) = CMPLX( REAL( VR( K, I ) ), ZERO )
   40    CONTINUE
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Undo scaling if necessary
</span><span class="comment">*</span><span class="comment">
</span>   50 CONTINUE
      IF( SCALEA ) THEN
         CALL <a name="CLASCL.385"></a><a href="clascl.f.html#CLASCL.1">CLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, N-INFO, 1, W( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         IF( INFO.GT.0 ) THEN
            CALL <a name="CLASCL.388"></a><a href="clascl.f.html#CLASCL.1">CLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, ILO-1, 1, W, N, IERR )
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      WORK( 1 ) = MAXWRK
      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="CGEEV.395"></a><a href="cgeev.f.html#CGEEV.1">CGEEV</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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