slaed7.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 312 行 · 第 1/2 页

</span><span class="comment">*</span><span class="comment">         in a Givens rotation.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  GIVNUM (input) REAL array, dimension (2, N lg N)
</span><span class="comment">*</span><span class="comment">         Each number indicates the S value to be used in the
</span><span class="comment">*</span><span class="comment">         corresponding Givens rotation.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  WORK   (workspace) REAL array, dimension (3*N+QSIZ*N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  IWORK  (workspace) INTEGER array, dimension (4*N)
</span><span class="comment">*</span><span class="comment">
</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:  if INFO = 1, an eigenvalue did not converge
</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">     Jeff Rutter, Computer Science Division, University of California
</span><span class="comment">*</span><span class="comment">     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>      REAL               ONE, ZERO
      PARAMETER          ( ONE = 1.0E0, ZERO = 0.0E0 )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      INTEGER            COLTYP, CURR, I, IDLMDA, INDX, INDXC, INDXP,
     $                   IQ2, IS, IW, IZ, K, LDQ2, N1, N2, PTR
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           SGEMM, <a name="SLAED8.171"></a><a href="slaed8.f.html#SLAED8.1">SLAED8</a>, <a name="SLAED9.171"></a><a href="slaed9.f.html#SLAED9.1">SLAED9</a>, <a name="SLAEDA.171"></a><a href="slaeda.f.html#SLAEDA.1">SLAEDA</a>, <a name="SLAMRG.171"></a><a href="slamrg.f.html#SLAMRG.1">SLAMRG</a>, <a name="XERBLA.171"></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">     .. Intrinsic Functions ..
</span>      INTRINSIC          MAX, MIN
<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 parameters.
</span><span class="comment">*</span><span class="comment">
</span>      INFO = 0
<span class="comment">*</span><span class="comment">
</span>      IF( ICOMPQ.LT.0 .OR. ICOMPQ.GT.1 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( ICOMPQ.EQ.1 .AND. QSIZ.LT.N ) THEN
         INFO = -4
      ELSE IF( LDQ.LT.MAX( 1, N ) ) THEN
         INFO = -9
      ELSE IF( MIN( 1, N ).GT.CUTPNT .OR. N.LT.CUTPNT ) THEN
         INFO = -12
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.194"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="SLAED7.194"></a><a href="slaed7.f.html#SLAED7.1">SLAED7</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
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     The following values are for bookkeeping purposes only.  They are
</span><span class="comment">*</span><span class="comment">     integer pointers which indicate the portion of the workspace
</span><span class="comment">*</span><span class="comment">     used by a particular array in <a name="SLAED8.205"></a><a href="slaed8.f.html#SLAED8.1">SLAED8</a> and <a name="SLAED9.205"></a><a href="slaed9.f.html#SLAED9.1">SLAED9</a>.
</span><span class="comment">*</span><span class="comment">
</span>      IF( ICOMPQ.EQ.1 ) THEN
         LDQ2 = QSIZ
      ELSE
         LDQ2 = N
      END IF
<span class="comment">*</span><span class="comment">
</span>      IZ = 1
      IDLMDA = IZ + N
      IW = IDLMDA + N
      IQ2 = IW + N
      IS = IQ2 + N*LDQ2
<span class="comment">*</span><span class="comment">
</span>      INDX = 1
      INDXC = INDX + N
      COLTYP = INDXC + N
      INDXP = COLTYP + N
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Form the z-vector which consists of the last row of Q_1 and the
</span><span class="comment">*</span><span class="comment">     first row of Q_2.
</span><span class="comment">*</span><span class="comment">
</span>      PTR = 1 + 2**TLVLS
      DO 10 I = 1, CURLVL - 1
         PTR = PTR + 2**( TLVLS-I )
   10 CONTINUE
      CURR = PTR + CURPBM
      CALL <a name="SLAEDA.232"></a><a href="slaeda.f.html#SLAEDA.1">SLAEDA</a>( N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR,
     $             GIVCOL, GIVNUM, QSTORE, QPTR, WORK( IZ ),
     $             WORK( IZ+N ), INFO )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     When solving the final problem, we no longer need the stored data,
</span><span class="comment">*</span><span class="comment">     so we will overwrite the data from this level onto the previously
</span><span class="comment">*</span><span class="comment">     used storage space.
</span><span class="comment">*</span><span class="comment">
</span>      IF( CURLVL.EQ.TLVLS ) THEN
         QPTR( CURR ) = 1
         PRMPTR( CURR ) = 1
         GIVPTR( CURR ) = 1
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Sort and Deflate eigenvalues.
</span><span class="comment">*</span><span class="comment">
</span>      CALL <a name="SLAED8.248"></a><a href="slaed8.f.html#SLAED8.1">SLAED8</a>( ICOMPQ, K, N, QSIZ, D, Q, LDQ, INDXQ, RHO, CUTPNT,
     $             WORK( IZ ), WORK( IDLMDA ), WORK( IQ2 ), LDQ2,
     $             WORK( IW ), PERM( PRMPTR( CURR ) ), GIVPTR( CURR+1 ),
     $             GIVCOL( 1, GIVPTR( CURR ) ),
     $             GIVNUM( 1, GIVPTR( CURR ) ), IWORK( INDXP ),
     $             IWORK( INDX ), INFO )
      PRMPTR( CURR+1 ) = PRMPTR( CURR ) + N
      GIVPTR( CURR+1 ) = GIVPTR( CURR+1 ) + GIVPTR( CURR )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Solve Secular Equation.
</span><span class="comment">*</span><span class="comment">
</span>      IF( K.NE.0 ) THEN
         CALL <a name="SLAED9.260"></a><a href="slaed9.f.html#SLAED9.1">SLAED9</a>( K, 1, K, N, D, WORK( IS ), K, RHO, WORK( IDLMDA ),
     $                WORK( IW ), QSTORE( QPTR( CURR ) ), K, INFO )
         IF( INFO.NE.0 )
     $      GO TO 30
         IF( ICOMPQ.EQ.1 ) THEN
            CALL SGEMM( <span class="string">'N'</span>, <span class="string">'N'</span>, QSIZ, K, K, ONE, WORK( IQ2 ), LDQ2,
     $                  QSTORE( QPTR( CURR ) ), K, ZERO, Q, LDQ )
         END IF
         QPTR( CURR+1 ) = QPTR( CURR ) + K**2
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Prepare the INDXQ sorting permutation.
</span><span class="comment">*</span><span class="comment">
</span>         N1 = K
         N2 = N - K
         CALL <a name="SLAMRG.274"></a><a href="slamrg.f.html#SLAMRG.1">SLAMRG</a>( N1, N2, D, 1, -1, INDXQ )
      ELSE
         QPTR( CURR+1 ) = QPTR( CURR )
         DO 20 I = 1, N
            INDXQ( I ) = I
   20    CONTINUE
      END IF
<span class="comment">*</span><span class="comment">
</span>   30 CONTINUE
      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="SLAED7.285"></a><a href="slaed7.f.html#SLAED7.1">SLAED7</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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