dlalsa.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 387 行 · 第 1/2 页

</span>      INFO = 0
<span class="comment">*</span><span class="comment">
</span>      IF( ( ICOMPQ.LT.0 ) .OR. ( ICOMPQ.GT.1 ) ) THEN
         INFO = -1
      ELSE IF( SMLSIZ.LT.3 ) THEN
         INFO = -2
      ELSE IF( N.LT.SMLSIZ ) THEN
         INFO = -3
      ELSE IF( NRHS.LT.1 ) THEN
         INFO = -4
      ELSE IF( LDB.LT.N ) THEN
         INFO = -6
      ELSE IF( LDBX.LT.N ) THEN
         INFO = -8
      ELSE IF( LDU.LT.N ) THEN
         INFO = -10
      ELSE IF( LDGCOL.LT.N ) THEN
         INFO = -19
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.196"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="DLALSA.196"></a><a href="dlalsa.f.html#DLALSA.1">DLALSA</a>'</span>, -INFO )
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Book-keeping and  setting up the computation tree.
</span><span class="comment">*</span><span class="comment">
</span>      INODE = 1
      NDIML = INODE + N
      NDIMR = NDIML + N
<span class="comment">*</span><span class="comment">
</span>      CALL <a name="DLASDT.206"></a><a href="dlasdt.f.html#DLASDT.1">DLASDT</a>( N, NLVL, ND, IWORK( INODE ), IWORK( NDIML ),
     $             IWORK( NDIMR ), SMLSIZ )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     The following code applies back the left singular vector factors.
</span><span class="comment">*</span><span class="comment">     For applying back the right singular vector factors, go to 50.
</span><span class="comment">*</span><span class="comment">
</span>      IF( ICOMPQ.EQ.1 ) THEN
         GO TO 50
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     The nodes on the bottom level of the tree were solved
</span><span class="comment">*</span><span class="comment">     by <a name="DLASDQ.217"></a><a href="dlasdq.f.html#DLASDQ.1">DLASDQ</a>. The corresponding left and right singular vector
</span><span class="comment">*</span><span class="comment">     matrices are in explicit form. First apply back the left
</span><span class="comment">*</span><span class="comment">     singular vector matrices.
</span><span class="comment">*</span><span class="comment">
</span>      NDB1 = ( ND+1 ) / 2
      DO 10 I = NDB1, ND
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        IC : center row of each node
</span><span class="comment">*</span><span class="comment">        NL : number of rows of left  subproblem
</span><span class="comment">*</span><span class="comment">        NR : number of rows of right subproblem
</span><span class="comment">*</span><span class="comment">        NLF: starting row of the left   subproblem
</span><span class="comment">*</span><span class="comment">        NRF: starting row of the right  subproblem
</span><span class="comment">*</span><span class="comment">
</span>         I1 = I - 1
         IC = IWORK( INODE+I1 )
         NL = IWORK( NDIML+I1 )
         NR = IWORK( NDIMR+I1 )
         NLF = IC - NL
         NRF = IC + 1
         CALL DGEMM( <span class="string">'T'</span>, <span class="string">'N'</span>, NL, NRHS, NL, ONE, U( NLF, 1 ), LDU,
     $               B( NLF, 1 ), LDB, ZERO, BX( NLF, 1 ), LDBX )
         CALL DGEMM( <span class="string">'T'</span>, <span class="string">'N'</span>, NR, NRHS, NR, ONE, U( NRF, 1 ), LDU,
     $               B( NRF, 1 ), LDB, ZERO, BX( NRF, 1 ), LDBX )
   10 CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Next copy the rows of B that correspond to unchanged rows
</span><span class="comment">*</span><span class="comment">     in the bidiagonal matrix to BX.
</span><span class="comment">*</span><span class="comment">
</span>      DO 20 I = 1, ND
         IC = IWORK( INODE+I-1 )
         CALL DCOPY( NRHS, B( IC, 1 ), LDB, BX( IC, 1 ), LDBX )
   20 CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Finally go through the left singular vector matrices of all
</span><span class="comment">*</span><span class="comment">     the other subproblems bottom-up on the tree.
</span><span class="comment">*</span><span class="comment">
</span>      J = 2**NLVL
      SQRE = 0
<span class="comment">*</span><span class="comment">
</span>      DO 40 LVL = NLVL, 1, -1
         LVL2 = 2*LVL - 1
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        find the first node LF and last node LL on
</span><span class="comment">*</span><span class="comment">        the current level LVL
</span><span class="comment">*</span><span class="comment">
</span>         IF( LVL.EQ.1 ) THEN
            LF = 1
            LL = 1
         ELSE
            LF = 2**( LVL-1 )
            LL = 2*LF - 1
         END IF
         DO 30 I = LF, LL
            IM1 = I - 1
            IC = IWORK( INODE+IM1 )
            NL = IWORK( NDIML+IM1 )
            NR = IWORK( NDIMR+IM1 )
            NLF = IC - NL
            NRF = IC + 1
            J = J - 1
            CALL <a name="DLALS0.277"></a><a href="dlals0.f.html#DLALS0.1">DLALS0</a>( ICOMPQ, NL, NR, SQRE, NRHS, BX( NLF, 1 ), LDBX,
     $                   B( NLF, 1 ), LDB, PERM( NLF, LVL ),
     $                   GIVPTR( J ), GIVCOL( NLF, LVL2 ), LDGCOL,
     $                   GIVNUM( NLF, LVL2 ), LDU, POLES( NLF, LVL2 ),
     $                   DIFL( NLF, LVL ), DIFR( NLF, LVL2 ),
     $                   Z( NLF, LVL ), K( J ), C( J ), S( J ), WORK,
     $                   INFO )
   30    CONTINUE
   40 CONTINUE
      GO TO 90
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     ICOMPQ = 1: applying back the right singular vector factors.
</span><span class="comment">*</span><span class="comment">
</span>   50 CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     First now go through the right singular vector matrices of all
</span><span class="comment">*</span><span class="comment">     the tree nodes top-down.
</span><span class="comment">*</span><span class="comment">
</span>      J = 0
      DO 70 LVL = 1, NLVL
         LVL2 = 2*LVL - 1
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Find the first node LF and last node LL on
</span><span class="comment">*</span><span class="comment">        the current level LVL.
</span><span class="comment">*</span><span class="comment">
</span>         IF( LVL.EQ.1 ) THEN
            LF = 1
            LL = 1
         ELSE
            LF = 2**( LVL-1 )
            LL = 2*LF - 1
         END IF
         DO 60 I = LL, LF, -1
            IM1 = I - 1
            IC = IWORK( INODE+IM1 )
            NL = IWORK( NDIML+IM1 )
            NR = IWORK( NDIMR+IM1 )
            NLF = IC - NL
            NRF = IC + 1
            IF( I.EQ.LL ) THEN
               SQRE = 0
            ELSE
               SQRE = 1
            END IF
            J = J + 1
            CALL <a name="DLALS0.322"></a><a href="dlals0.f.html#DLALS0.1">DLALS0</a>( ICOMPQ, NL, NR, SQRE, NRHS, B( NLF, 1 ), LDB,
     $                   BX( NLF, 1 ), LDBX, PERM( NLF, LVL ),
     $                   GIVPTR( J ), GIVCOL( NLF, LVL2 ), LDGCOL,
     $                   GIVNUM( NLF, LVL2 ), LDU, POLES( NLF, LVL2 ),
     $                   DIFL( NLF, LVL ), DIFR( NLF, LVL2 ),
     $                   Z( NLF, LVL ), K( J ), C( J ), S( J ), WORK,
     $                   INFO )
   60    CONTINUE
   70 CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     The nodes on the bottom level of the tree were solved
</span><span class="comment">*</span><span class="comment">     by <a name="DLASDQ.333"></a><a href="dlasdq.f.html#DLASDQ.1">DLASDQ</a>. The corresponding right singular vector
</span><span class="comment">*</span><span class="comment">     matrices are in explicit form. Apply them back.
</span><span class="comment">*</span><span class="comment">
</span>      NDB1 = ( ND+1 ) / 2
      DO 80 I = NDB1, ND
         I1 = I - 1
         IC = IWORK( INODE+I1 )
         NL = IWORK( NDIML+I1 )
         NR = IWORK( NDIMR+I1 )
         NLP1 = NL + 1
         IF( I.EQ.ND ) THEN
            NRP1 = NR
         ELSE
            NRP1 = NR + 1
         END IF
         NLF = IC - NL
         NRF = IC + 1
         CALL DGEMM( <span class="string">'T'</span>, <span class="string">'N'</span>, NLP1, NRHS, NLP1, ONE, VT( NLF, 1 ), LDU,
     $               B( NLF, 1 ), LDB, ZERO, BX( NLF, 1 ), LDBX )
         CALL DGEMM( <span class="string">'T'</span>, <span class="string">'N'</span>, NRP1, NRHS, NRP1, ONE, VT( NRF, 1 ), LDU,
     $               B( NRF, 1 ), LDB, ZERO, BX( NRF, 1 ), LDBX )
   80 CONTINUE
<span class="comment">*</span><span class="comment">
</span>   90 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="DLALSA.360"></a><a href="dlalsa.f.html#DLALSA.1">DLALSA</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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