cggbak.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 245 行 · 第 1/2 页

      ELSE IF( .NOT.RIGHTV .AND. .NOT.LEFTV ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( ILO.LT.1 ) THEN
         INFO = -4
      ELSE IF( N.EQ.0 .AND. IHI.EQ.0 .AND. ILO.NE.1 ) THEN
         INFO = -4
      ELSE IF( N.GT.0 .AND. ( IHI.LT.ILO .OR. IHI.GT.MAX( 1, N ) ) )
     $   THEN
         INFO = -5
      ELSE IF( N.EQ.0 .AND. ILO.EQ.1 .AND. IHI.NE.0 ) THEN
         INFO = -5
      ELSE IF( M.LT.0 ) THEN
         INFO = -8
      ELSE IF( LDV.LT.MAX( 1, N ) ) THEN
         INFO = -10
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.124"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="CGGBAK.124"></a><a href="cggbak.f.html#CGGBAK.1">CGGBAK</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.EQ.0 )
     $   RETURN
      IF( M.EQ.0 )
     $   RETURN
      IF( <a name="LSAME.134"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOB, <span class="string">'N'</span> ) )
     $   RETURN
<span class="comment">*</span><span class="comment">
</span>      IF( ILO.EQ.IHI )
     $   GO TO 30
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Backward balance
</span><span class="comment">*</span><span class="comment">
</span>      IF( <a name="LSAME.142"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOB, <span class="string">'S'</span> ) .OR. <a name="LSAME.142"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOB, <span class="string">'B'</span> ) ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Backward transformation on right eigenvectors
</span><span class="comment">*</span><span class="comment">
</span>         IF( RIGHTV ) THEN
            DO 10 I = ILO, IHI
               CALL CSSCAL( M, RSCALE( I ), V( I, 1 ), LDV )
   10       CONTINUE
         END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Backward transformation on left eigenvectors
</span><span class="comment">*</span><span class="comment">
</span>         IF( LEFTV ) THEN
            DO 20 I = ILO, IHI
               CALL CSSCAL( M, LSCALE( I ), V( I, 1 ), LDV )
   20       CONTINUE
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Backward permutation
</span><span class="comment">*</span><span class="comment">
</span>   30 CONTINUE
      IF( <a name="LSAME.164"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOB, <span class="string">'P'</span> ) .OR. <a name="LSAME.164"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOB, <span class="string">'B'</span> ) ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Backward permutation on right eigenvectors
</span><span class="comment">*</span><span class="comment">
</span>         IF( RIGHTV ) THEN
            IF( ILO.EQ.1 )
     $         GO TO 50
            DO 40 I = ILO - 1, 1, -1
               K = RSCALE( I )
               IF( K.EQ.I )
     $            GO TO 40
               CALL CSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   40       CONTINUE
<span class="comment">*</span><span class="comment">
</span>   50       CONTINUE
            IF( IHI.EQ.N )
     $         GO TO 70
            DO 60 I = IHI + 1, N
               K = RSCALE( I )
               IF( K.EQ.I )
     $            GO TO 60
               CALL CSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   60       CONTINUE
         END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Backward permutation on left eigenvectors
</span><span class="comment">*</span><span class="comment">
</span>   70    CONTINUE
         IF( LEFTV ) THEN
            IF( ILO.EQ.1 )
     $         GO TO 90
            DO 80 I = ILO - 1, 1, -1
               K = LSCALE( I )
               IF( K.EQ.I )
     $            GO TO 80
               CALL CSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   80       CONTINUE
<span class="comment">*</span><span class="comment">
</span>   90       CONTINUE
            IF( IHI.EQ.N )
     $         GO TO 110
            DO 100 I = IHI + 1, N
               K = LSCALE( I )
               IF( K.EQ.I )
     $            GO TO 100
               CALL CSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
  100       CONTINUE
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>  110 CONTINUE
<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="CGGBAK.218"></a><a href="cggbak.f.html#CGGBAK.1">CGGBAK</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

</pre>

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