dgeevx.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 581 行 · 第 1/4 页

</span><span class="comment">*</span><span class="comment">        (Workspace: need 2*N-1, prefer N+(N-1)*NB)
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DORGHR.422"></a><a href="dorghr.f.html#DORGHR.1">DORGHR</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">        (Workspace: need 1, prefer HSWORK (see comments) )
</span><span class="comment">*</span><span class="comment">
</span>         IWRK = ITAU
         CALL <a name="DHSEQR.429"></a><a href="dhseqr.f.html#DHSEQR.1">DHSEQR</a>( <span class="string">'S'</span>, <span class="string">'V'</span>, N, ILO, IHI, A, LDA, WR, WI, 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">        If condition numbers desired, compute Schur form
</span><span class="comment">*</span><span class="comment">
</span>         IF( WNTSNN ) THEN
            JOB = <span class="string">'E'</span>
         ELSE
            JOB = <span class="string">'S'</span>
         END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        (Workspace: need 1, prefer HSWORK (see comments) )
</span><span class="comment">*</span><span class="comment">
</span>         IWRK = ITAU
         CALL <a name="DHSEQR.446"></a><a href="dhseqr.f.html#DHSEQR.1">DHSEQR</a>( JOB, <span class="string">'N'</span>, N, ILO, IHI, A, LDA, WR, WI, 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="DHSEQR.450"></a><a href="dhseqr.f.html#DHSEQR.1">DHSEQR</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">        (Workspace: need 3*N)
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DTREVC.460"></a><a href="dtrevc.f.html#DTREVC.1">DTREVC</a>( SIDE, <span class="string">'B'</span>, SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
     $                N, NOUT, WORK( IWRK ), IERR )
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Compute condition numbers if desired
</span><span class="comment">*</span><span class="comment">     (Workspace: need N*N+6*N unless SENSE = 'E')
</span><span class="comment">*</span><span class="comment">
</span>      IF( .NOT.WNTSNN ) THEN
         CALL <a name="DTRSNA.468"></a><a href="dtrsna.f.html#DTRSNA.1">DTRSNA</a>( SENSE, <span class="string">'A'</span>, SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
     $                RCONDE, RCONDV, N, NOUT, WORK( IWRK ), N, IWORK,
     $                ICOND )
      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">
</span>         CALL <a name="DGEBAK.477"></a><a href="dgebak.f.html#DGEBAK.1">DGEBAK</a>( BALANC, <span class="string">'L'</span>, N, ILO, IHI, SCALE, 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
            IF( WI( I ).EQ.ZERO ) THEN
               SCL = ONE / DNRM2( N, VL( 1, I ), 1 )
               CALL DSCAL( N, SCL, VL( 1, I ), 1 )
            ELSE IF( WI( I ).GT.ZERO ) THEN
               SCL = ONE / <a name="DLAPY2.487"></a><a href="dlapy2.f.html#DLAPY2.1">DLAPY2</a>( DNRM2( N, VL( 1, I ), 1 ),
     $               DNRM2( N, VL( 1, I+1 ), 1 ) )
               CALL DSCAL( N, SCL, VL( 1, I ), 1 )
               CALL DSCAL( N, SCL, VL( 1, I+1 ), 1 )
               DO 10 K = 1, N
                  WORK( K ) = VL( K, I )**2 + VL( K, I+1 )**2
   10          CONTINUE
               K = IDAMAX( N, WORK, 1 )
               CALL <a name="DLARTG.495"></a><a href="dlartg.f.html#DLARTG.1">DLARTG</a>( VL( K, I ), VL( K, I+1 ), CS, SN, R )
               CALL DROT( N, VL( 1, I ), 1, VL( 1, I+1 ), 1, CS, SN )
               VL( K, I+1 ) = ZERO
            END IF
   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">
</span>         CALL <a name="DGEBAK.506"></a><a href="dgebak.f.html#DGEBAK.1">DGEBAK</a>( BALANC, <span class="string">'R'</span>, N, ILO, IHI, SCALE, 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
            IF( WI( I ).EQ.ZERO ) THEN
               SCL = ONE / DNRM2( N, VR( 1, I ), 1 )
               CALL DSCAL( N, SCL, VR( 1, I ), 1 )
            ELSE IF( WI( I ).GT.ZERO ) THEN
               SCL = ONE / <a name="DLAPY2.516"></a><a href="dlapy2.f.html#DLAPY2.1">DLAPY2</a>( DNRM2( N, VR( 1, I ), 1 ),
     $               DNRM2( N, VR( 1, I+1 ), 1 ) )
               CALL DSCAL( N, SCL, VR( 1, I ), 1 )
               CALL DSCAL( N, SCL, VR( 1, I+1 ), 1 )
               DO 30 K = 1, N
                  WORK( K ) = VR( K, I )**2 + VR( K, I+1 )**2
   30          CONTINUE
               K = IDAMAX( N, WORK, 1 )
               CALL <a name="DLARTG.524"></a><a href="dlartg.f.html#DLARTG.1">DLARTG</a>( VR( K, I ), VR( K, I+1 ), CS, SN, R )
               CALL DROT( N, VR( 1, I ), 1, VR( 1, I+1 ), 1, CS, SN )
               VR( K, I+1 ) = ZERO
            END IF
   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="DLASCL.535"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, N-INFO, 1, WR( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         CALL <a name="DLASCL.537"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, N-INFO, 1, WI( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         IF( INFO.EQ.0 ) THEN
            IF( ( WNTSNV .OR. WNTSNB ) .AND. ICOND.EQ.0 )
     $         CALL <a name="DLASCL.541"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, N, 1, RCONDV, N,
     $                      IERR )
         ELSE
            CALL <a name="DLASCL.544"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, ILO-1, 1, WR, N,
     $                   IERR )
            CALL <a name="DLASCL.546"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, CSCALE, ANRM, ILO-1, 1, WI, 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="DGEEVX.554"></a><a href="dgeevx.f.html#DGEEVX.1">DGEEVX</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

</pre>

 </body>
</html>