pdlamr1d.f

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      SUBROUTINE pdlamr1d( N, A, IA, JA, DESCA, B, IB, JB, DESCB )
*
*  -- ScaLAPACK routine (version 1.7) --
*     University of Tennessee, Knoxville, Oak Ridge National Laboratory,
*     and University of California, Berkeley.
*     October 15, 1999
*
*     .. Scalar Arguments ..
      INTEGER            IA, IB, JA, JB, N
*     ..
*     .. Array Arguments ..
      INTEGER            DESCA( * ), DESCB( * )
      DOUBLE PRECISION   A( * ), B( * )
*     ..
*
*  Bugs
*  ====
*
*  I am not sure that this works correctly when IB and JB are not equal
*  to 1.  Indeed, I suspect that IB should always be set to 1 or ignored
*  with 1 used in its place.
*
*  PDLAMR1D has not been tested except withint the contect of
*  PDSYPTRD, the prototype reduction to tridiagonal form code.
*
*  Purpose
*
*  =======
*
*  PDLAMR1D redistributes a one-dimensional row vector from one data
*  decomposition to another.
*
*  This is an auxiliary routine called by PDSYTRD to redistribute D, E
*  and TAU.
*
*  Notes
*  =====
*
*  Although all processes call PDGEMR2D, only the processes that own
*  the first column of A send data and only processes that own the
*  first column of B receive data.  The calls to DGEBS2D/DGEBR2D
*  spread the data down.
*
*  Arguments
*  =========
*
*  N       (global input) INTEGER
*          The size of the matrix to be transposed.
*
*  A       (local output) COMPLEX*16 pointer into the
*          local memory to an array of dimension (LOCc(JA+N-1)).
*          On output, A is replicated across all processes in
*          this processor column.
*
*  IA      (global input) INTEGER
*          A's global row index, which points to the beginning of
*          the submatrix which is to be operated on.
*
*  JA      (global input) INTEGER
*          A's global column index, which points to the beginning of
*          the submatrix which is to be operated on.
*
*  DESCA   (global and local input) INTEGER array of dimension DLEN_.
*          The array descriptor for the distributed matrix A.
*
*  B       (local input/local output) COMPLEX*16 pointer into the
*          local memory to an array of dimension (LOCc(JB+N-1)).
*
*  IB      (global input) INTEGER
*          B's global row index,  NOT USED
*
*  JB      (global input) INTEGER
*          B's global column index, which points to the beginning of
*          the submatrix which is to be operated on.
*
*  DESCB   (global and local input) INTEGER array of dimension DLEN_.
*          The array descriptor for the distributed matrix B.
*
*  WORK    (local workspace) COMPLEX*16 array, dimension ( LWORK )
*
*  LWORK   (local input) INTEGER
*          The dimension of the array WORK.
*          LWORK is local input and must be at least
*          LWORK >= NB * NUMROC( N, 1, 0, 0, NPROW )
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            BLOCK_CYCLIC_2D, DLEN_, DTYPE_, CTXT_, M_, N_,
     $                   MB_, NB_, RSRC_, CSRC_, LLD_
      parameter( block_cyclic_2d = 1, dlen_ = 9, dtype_ = 1,
     $                   ctxt_ = 2, m_ = 3, n_ = 4, mb_ = 5, nb_ = 6,
     $                   rsrc_ = 7, csrc_ = 8, lld_ = 9 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, ICTXT, MYCOL, MYROW, NPCOL, NPROW, NQ
*     ..
*     .. Local Arrays ..
      INTEGER            DESCAA( DLEN_ ), DESCBB( DLEN_ )
*     ..
*     .. External Subroutines ..
      EXTERNAL           blacs_gridinfo, dgebr2d, dgebs2d, pdgemr2d
*     ..
*     .. External Functions ..
      INTEGER            NUMROC
      EXTERNAL           numroc
*     ..
*     .. Executable Statements ..
*       This is just to keep ftnchek and toolpack/1 happy
      IF( block_cyclic_2d*csrc_*ctxt_*dlen_*dtype_*lld_*mb_*m_*nb_*n_*
     $    rsrc_.LT.0 )RETURN
*
*     Quick return if possible
*
      IF( n.LE.0 )
     $   RETURN
*
      DO 10 i = 1, dlen_
         descaa( i ) = desca( i )
         descbb( i ) = descb( i )
   10 CONTINUE
*
      descaa( m_ ) = 1
      descbb( m_ ) = 1
      descaa( lld_ ) = 1
      descbb( lld_ ) = 1
*
      ictxt = descb( ctxt_ )
      CALL pdgemr2d( 1, n, a, ia, ja, descaa, b, ib, jb, descbb, ictxt )
*
      CALL blacs_gridinfo( ictxt, nprow, npcol, myrow, mycol )
      nq = numroc( n, descb( nb_ ), mycol, 0, npcol )
*
      IF( myrow.EQ.0 ) THEN
         CALL dgebs2d( ictxt, 'C', ' ', nq, 1, b, nq )
      ELSE
         CALL dgebr2d( ictxt, 'C', ' ', nq, 1, b, nq, 0, mycol )
      END IF
*
      RETURN
*
*     End of PDLAMR1D
*
      END