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来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 422 行 · 第 1/3 页

<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Functions ..
</span>      LOGICAL            <a name="LSAME.125"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
      INTEGER            <a name="ILAENV.126"></a><a href="hfy-index.html#ILAENV">ILAENV</a>, ISAMAX
      REAL               <a name="CLANGE.127"></a><a href="clange.f.html#CLANGE.1">CLANGE</a>, SCNRM2, <a name="SLAMCH.127"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
      EXTERNAL           <a name="LSAME.128"></a><a href="lsame.f.html#LSAME.1">LSAME</a>, <a name="ILAENV.128"></a><a href="hfy-index.html#ILAENV">ILAENV</a>, ISAMAX, <a name="CLANGE.128"></a><a href="clange.f.html#CLANGE.1">CLANGE</a>, SCNRM2, <a name="SLAMCH.128"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          AIMAG, CMPLX, CONJG, MAX, REAL, SQRT
<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">     Test the input arguments
</span><span class="comment">*</span><span class="comment">
</span>      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      WANTVL = <a name="LSAME.139"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBVL, <span class="string">'V'</span> )
      WANTVR = <a name="LSAME.140"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBVR, <span class="string">'V'</span> )
      IF( ( .NOT.WANTVL ) .AND. ( .NOT.<a name="LSAME.141"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBVL, <span class="string">'N'</span> ) ) ) THEN
         INFO = -1
      ELSE IF( ( .NOT.WANTVR ) .AND. ( .NOT.<a name="LSAME.143"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBVR, <span class="string">'N'</span> ) ) ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDVL.LT.1 .OR. ( WANTVL .AND. LDVL.LT.N ) ) THEN
         INFO = -8
      ELSE IF( LDVR.LT.1 .OR. ( WANTVR .AND. LDVR.LT.N ) ) THEN
         INFO = -10
      END IF

<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Compute workspace
</span><span class="comment">*</span><span class="comment">      (Note: Comments in the code beginning &quot;Workspace:&quot; describe the
</span><span class="comment">*</span><span class="comment">       minimal amount of workspace needed at that point in the code,
</span><span class="comment">*</span><span class="comment">       as well as the preferred amount for good performance.
</span><span class="comment">*</span><span class="comment">       CWorkspace refers to complex workspace, and RWorkspace to real
</span><span class="comment">*</span><span class="comment">       workspace. NB refers to the optimal block size for the
</span><span class="comment">*</span><span class="comment">       immediately following subroutine, as returned by <a name="ILAENV.162"></a><a href="hfy-index.html#ILAENV">ILAENV</a>.
</span><span class="comment">*</span><span class="comment">       HSWORK refers to the workspace preferred by <a name="CHSEQR.163"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>, as
</span><span class="comment">*</span><span class="comment">       calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
</span><span class="comment">*</span><span class="comment">       the worst case.)
</span><span class="comment">*</span><span class="comment">
</span>      IF( INFO.EQ.0 ) THEN
         IF( N.EQ.0 ) THEN
            MINWRK = 1
            MAXWRK = 1
         ELSE
            MAXWRK = N + N*<a name="ILAENV.172"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="CGEHRD.172"></a><a href="cgehrd.f.html#CGEHRD.1">CGEHRD</a>'</span>, <span class="string">' '</span>, N, 1, N, 0 )
            MINWRK = 2*N
            IF( WANTVL ) THEN
               MAXWRK = MAX( MAXWRK, N + ( N - 1 )*<a name="ILAENV.175"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="CUNGHR.175"></a><a href="cunghr.f.html#CUNGHR.1">CUNGHR</a>'</span>,
     $                       <span class="string">' '</span>, N, 1, N, -1 ) )
               CALL <a name="CHSEQR.177"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>( <span class="string">'S'</span>, <span class="string">'V'</span>, N, 1, N, A, LDA, W, VL, LDVL,
     $                WORK, -1, INFO )
            ELSE IF( WANTVR ) THEN
               MAXWRK = MAX( MAXWRK, N + ( N - 1 )*<a name="ILAENV.180"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="CUNGHR.180"></a><a href="cunghr.f.html#CUNGHR.1">CUNGHR</a>'</span>,
     $                       <span class="string">' '</span>, N, 1, N, -1 ) )
               CALL <a name="CHSEQR.182"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>( <span class="string">'S'</span>, <span class="string">'V'</span>, N, 1, N, A, LDA, W, VR, LDVR,
     $                WORK, -1, INFO )
            ELSE
               CALL <a name="CHSEQR.185"></a><a href="chseqr.f.html#CHSEQR.1">CHSEQR</a>( <span class="string">'E'</span>, <span class="string">'N'</span>, N, 1, N, A, LDA, W, VR, LDVR,
     $                WORK, -1, INFO )
            END IF
            HSWORK = WORK( 1 )
            MAXWRK = MAX( MAXWRK, HSWORK, MINWRK )
         END IF
         WORK( 1 ) = MAXWRK
<span class="comment">*</span><span class="comment">
</span>         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -12
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.199"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="CGEEV.199"></a><a href="cgeev.f.html#CGEEV.1">CGEEV</a> '</span>, -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         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
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Get machine constants
</span><span class="comment">*</span><span class="comment">
</span>      EPS = <a name="SLAMCH.212"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>( <span class="string">'P'</span> )
      SMLNUM = <a name="SLAMCH.213"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>( <span class="string">'S'</span> )
      BIGNUM = ONE / SMLNUM
      CALL <a name="SLABAD.215"></a><a href="slabad.f.html#SLABAD.1">SLABAD</a>( SMLNUM, BIGNUM )
      SMLNUM = SQRT( SMLNUM ) / EPS
      BIGNUM = ONE / SMLNUM
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Scale A if max element outside range [SMLNUM,BIGNUM]
</span><span class="comment">*</span><span class="comment">
</span>      ANRM = <a name="CLANGE.221"></a><a href="clange.f.html#CLANGE.1">CLANGE</a>( <span class="string">'M'</span>, N, N, A, LDA, DUM )
      SCALEA = .FALSE.
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = SMLNUM
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = BIGNUM
      END IF
      IF( SCALEA )
     $   CALL <a name="CLASCL.231"></a><a href="clascl.f.html#CLASCL.1">CLASCL</a>( <span class="string">'G'</span>, 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Balance the matrix
</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>      IBAL = 1
      CALL <a name="CGEBAL.238"></a><a href="cgebal.f.html#CGEBAL.1">CGEBAL</a>( <span class="string">'B'</span>, N, A, LDA, ILO, IHI, RWORK( IBAL ), IERR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Reduce to upper Hessenberg form
</span><span class="comment">*</span><span class="comment">     (CWorkspace: need 2*N, prefer N+N*NB)
</span><span class="comment">*</span><span class="comment">     (RWorkspace: none)
</span><span class="comment">*</span><span class="comment">
</span>      ITAU = 1
      IWRK = ITAU + N
      CALL <a name="CGEHRD.246"></a><a href="cgehrd.f.html#CGEHRD.1">CGEHRD</a>( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
     $             LWORK-IWRK+1, IERR )
<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">        Want left eigenvectors
</span><span class="comment">*</span><span class="comment">        Copy Householder vectors to VL
</span><span class="comment">*</span><span class="comment">
</span>         SIDE = <span class="string">'L'</span>
         CALL <a name="CLACPY.255"></a><a href="clacpy.f.html#CLACPY.1">CLACPY</a>( <span class="string">'L'</span>, N, N, A, LDA, VL, LDVL )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Generate unitary matrix in VL
</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.261"></a><a href="cunghr.f.html#CUNGHR.1">CUNGHR</a>( N, ILO, IHI, VL, LDVL, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
<span class="comment">*</span><span class="comment">