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来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 741 行 · 第 1/5 页

</span><span class="comment">*</span><span class="comment">  INFO    (output) INTEGER
</span><span class="comment">*</span><span class="comment">          = 0:  successful exit.
</span><span class="comment">*</span><span class="comment">          &lt; 0:  if INFO = -i, the i-th argument had an illegal value.
</span><span class="comment">*</span><span class="comment">          &gt; 0:  <a name="DBDSDC.134"></a><a href="dbdsdc.f.html#DBDSDC.1">DBDSDC</a> did not converge, updating process failed.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Further Details
</span><span class="comment">*</span><span class="comment">  ===============
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Based on contributions by
</span><span class="comment">*</span><span class="comment">     Ming Gu and Huan Ren, Computer Science Division, University of
</span><span class="comment">*</span><span class="comment">     California at Berkeley, USA
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Parameters ..
</span>      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      LOGICAL            LQUERY, WNTQA, WNTQAS, WNTQN, WNTQO, WNTQS
      INTEGER            BDSPAC, BLK, CHUNK, I, IE, IERR, IL,
     $                   IR, ISCL, ITAU, ITAUP, ITAUQ, IU, IVT, LDWKVT,
     $                   LDWRKL, LDWRKR, LDWRKU, MAXWRK, MINMN, MINWRK,
     $                   MNTHR, NWORK, WRKBL
      DOUBLE PRECISION   ANRM, BIGNUM, EPS, SMLNUM
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Arrays ..
</span>      INTEGER            IDUM( 1 )
      DOUBLE PRECISION   DUM( 1 )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           <a name="DBDSDC.162"></a><a href="dbdsdc.f.html#DBDSDC.1">DBDSDC</a>, <a name="DGEBRD.162"></a><a href="dgebrd.f.html#DGEBRD.1">DGEBRD</a>, <a name="DGELQF.162"></a><a href="dgelqf.f.html#DGELQF.1">DGELQF</a>, DGEMM, <a name="DGEQRF.162"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>, <a name="DLACPY.162"></a><a href="dlacpy.f.html#DLACPY.1">DLACPY</a>,
     $                   <a name="DLASCL.163"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>, <a name="DLASET.163"></a><a href="dlaset.f.html#DLASET.1">DLASET</a>, <a name="DORGBR.163"></a><a href="dorgbr.f.html#DORGBR.1">DORGBR</a>, <a name="DORGLQ.163"></a><a href="dorglq.f.html#DORGLQ.1">DORGLQ</a>, <a name="DORGQR.163"></a><a href="dorgqr.f.html#DORGQR.1">DORGQR</a>, <a name="DORMBR.163"></a><a href="dormbr.f.html#DORMBR.1">DORMBR</a>,
     $                   <a name="XERBLA.164"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Functions ..
</span>      LOGICAL            <a name="LSAME.167"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
      INTEGER            <a name="ILAENV.168"></a><a href="hfy-index.html#ILAENV">ILAENV</a>
      DOUBLE PRECISION   <a name="DLAMCH.169"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>, <a name="DLANGE.169"></a><a href="dlange.f.html#DLANGE.1">DLANGE</a>
      EXTERNAL           <a name="DLAMCH.170"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>, <a name="DLANGE.170"></a><a href="dlange.f.html#DLANGE.1">DLANGE</a>, <a name="ILAENV.170"></a><a href="hfy-index.html#ILAENV">ILAENV</a>, <a name="LSAME.170"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          INT, MAX, MIN, 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
      MINMN = MIN( M, N )
      WNTQA = <a name="LSAME.181"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBZ, <span class="string">'A'</span> )
      WNTQS = <a name="LSAME.182"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBZ, <span class="string">'S'</span> )
      WNTQAS = WNTQA .OR. WNTQS
      WNTQO = <a name="LSAME.184"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBZ, <span class="string">'O'</span> )
      WNTQN = <a name="LSAME.185"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBZ, <span class="string">'N'</span> )
      LQUERY = ( LWORK.EQ.-1 )
<span class="comment">*</span><span class="comment">
</span>      IF( .NOT.( WNTQA .OR. WNTQS .OR. WNTQO .OR. WNTQN ) ) THEN
         INFO = -1
      ELSE IF( M.LT.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDU.LT.1 .OR. ( WNTQAS .AND. LDU.LT.M ) .OR.
     $         ( WNTQO .AND. M.LT.N .AND. LDU.LT.M ) ) THEN
         INFO = -8
      ELSE IF( LDVT.LT.1 .OR. ( WNTQA .AND. LDVT.LT.N ) .OR.
     $         ( WNTQS .AND. LDVT.LT.MINMN ) .OR.
     $         ( WNTQO .AND. M.GE.N .AND. LDVT.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">       NB refers to the optimal block size for the immediately
</span><span class="comment">*</span><span class="comment">       following subroutine, as returned by <a name="ILAENV.210"></a><a href="hfy-index.html#ILAENV">ILAENV</a>.)
</span><span class="comment">*</span><span class="comment">
</span>      IF( INFO.EQ.0 ) THEN
         MINWRK = 1
         MAXWRK = 1
         IF( M.GE.N .AND. MINMN.GT.0 ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Compute space needed for <a name="DBDSDC.217"></a><a href="dbdsdc.f.html#DBDSDC.1">DBDSDC</a>
</span><span class="comment">*</span><span class="comment">
</span>            MNTHR = INT( MINMN*11.0D0 / 6.0D0 )
            IF( WNTQN ) THEN
               BDSPAC = 7*N
            ELSE
               BDSPAC = 3*N*N + 4*N
            END IF
            IF( M.GE.MNTHR ) THEN
               IF( WNTQN ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">                 Path 1 (M much larger than N, JOBZ='N')
</span><span class="comment">*</span><span class="comment">
</span>                  WRKBL = N + N*<a name="ILAENV.230"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEQRF.230"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>'</span>, <span class="string">' '</span>, M, N, -1,
     $                    -1 )
                  WRKBL = MAX( WRKBL, 3*N+2*N*
     $                    <a name="ILAENV.233"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEBRD.233"></a><a href="dgebrd.f.html#DGEBRD.1">DGEBRD</a>'</span>, <span class="string">' '</span>, N, N, -1, -1 ) )
                  MAXWRK = MAX( WRKBL, BDSPAC+N )
                  MINWRK = BDSPAC + N
               ELSE IF( WNTQO ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">                 Path 2 (M much larger than N, JOBZ='O')
</span><span class="comment">*</span><span class="comment">
</span>                  WRKBL = N + N*<a name="ILAENV.240"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEQRF.240"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>'</span>, <span class="string">' '</span>, M, N, -1, -1 )
                  WRKBL = MAX( WRKBL, N+N*<a name="ILAENV.241"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORGQR.241"></a><a href="dorgqr.f.html#DORGQR.1">DORGQR</a>'</span>, <span class="string">' '</span>, M,
     $                    N, N, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+2*N*
     $                    <a name="ILAENV.244"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEBRD.244"></a><a href="dgebrd.f.html#DGEBRD.1">DGEBRD</a>'</span>, <span class="string">' '</span>, N, N, -1, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+N*
     $                    <a name="ILAENV.246"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMBR.246"></a><a href="dormbr.f.html#DORMBR.1">DORMBR</a>'</span>, <span class="string">'QLN'</span>, N, N, N, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+N*
     $                    <a name="ILAENV.248"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMBR.248"></a><a href="dormbr.f.html#DORMBR.1">DORMBR</a>'</span>, <span class="string">'PRT'</span>, N, N, N, -1 ) )
                  WRKBL = MAX( WRKBL, BDSPAC+3*N )
                  MAXWRK = WRKBL + 2*N*N
                  MINWRK = BDSPAC + 2*N*N + 3*N
               ELSE IF( WNTQS ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">                 Path 3 (M much larger than N, JOBZ='S')
</span><span class="comment">*</span><span class="comment">
</span>                  WRKBL = N + N*<a name="ILAENV.256"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEQRF.256"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>'</span>, <span class="string">' '</span>, M, N, -1, -1 )
                  WRKBL = MAX( WRKBL, N+N*<a name="ILAENV.257"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORGQR.257"></a><a href="dorgqr.f.html#DORGQR.1">DORGQR</a>'</span>, <span class="string">' '</span>, M,
     $                    N, N, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+2*N*
     $                    <a name="ILAENV.260"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEBRD.260"></a><a href="dgebrd.f.html#DGEBRD.1">DGEBRD</a>'</span>, <span class="string">' '</span>, N, N, -1, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+N*
     $                    <a name="ILAENV.262"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMBR.262"></a><a href="dormbr.f.html#DORMBR.1">DORMBR</a>'</span>, <span class="string">'QLN'</span>, N, N, N, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+N*
     $                    <a name="ILAENV.264"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMBR.264"></a><a href="dormbr.f.html#DORMBR.1">DORMBR</a>'</span>, <span class="string">'PRT'</span>, N, N, N, -1 ) )
                  WRKBL = MAX( WRKBL, BDSPAC+3*N )
                  MAXWRK = WRKBL + N*N
                  MINWRK = BDSPAC + N*N + 3*N
               ELSE IF( WNTQA ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">                 Path 4 (M much larger than N, JOBZ='A')
</span><span class="comment">*</span><span class="comment">
</span>                  WRKBL = N + N*<a name="ILAENV.272"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEQRF.272"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>'</span>, <span class="string">' '</span>, M, N, -1, -1 )
                  WRKBL = MAX( WRKBL, N+M*<a name="ILAENV.273"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORGQR.273"></a><a href="dorgqr.f.html#DORGQR.1">DORGQR</a>'</span>, <span class="string">' '</span>, M,
     $                    M, N, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+2*N*
     $                    <a name="ILAENV.276"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEBRD.276"></a><a href="dgebrd.f.html#DGEBRD.1">DGEBRD</a>'</span>, <span class="string">' '</span>, N, N, -1, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+N*
     $                    <a name="ILAENV.278"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMBR.278"></a><a href="dormbr.f.html#DORMBR.1">DORMBR</a>'</span>, <span class="string">'QLN'</span>, N, N, N, -1 ) )
                  WRKBL = MAX( WRKBL, 3*N+N*