NAME

       PSLACP3  - i an auxiliary routine that copies from a global parallel  array into a local replicated array
       or vise versa

SYNOPSIS

       SUBROUTINE PSLACP3( M, I, A, DESCA, B, LDB, II, JJ, REV )

           INTEGER         I, II, JJ, LDB, M, REV

           INTEGER         DESCA( * )

           REAL            A( * ), B( LDB, * )

PURPOSE

       PSLACP3 is an auxiliary routine that copies from a global parallel
         array into a local replicated array or vise versa.  Notice that
         the entire submatrix that is copied gets placed on one node or
         more.  The receiving node can be specified precisely, or all nodes
         can receive, or just one row or column of nodes.

       Notes
       =====

       Each global data object is described by  an  associated  description  vector.   This  vector  stores  the
       information required to establish the mapping between an object element and its corresponding process and
       memory location.

       Let A be a generic term for any 2D block  cyclicly  distributed  array.   Such  a  global  array  has  an
       associated  description  vector  DESCA.  In the following comments, the character _ should be read as "of
       the global array".

       NOTATION        STORED IN      EXPLANATION
       --------------- -------------- -------------------------------------- DTYPE_A(global) DESCA( DTYPE_  )The
       descriptor type.  In this case,
                                      DTYPE_A = 1.
       CTXT_A (global) DESCA( CTXT_ ) The BLACS context handle, indicating
                                      the BLACS process grid A is distribu-
                                      ted over. The context itself is glo-
                                      bal, but the handle (the integer
                                      value) may vary.
       M_A    (global) DESCA( M_ )    The number of rows in the global
                                      array A.
       N_A    (global) DESCA( N_ )    The number of columns in the global
                                      array A.
       MB_A   (global) DESCA( MB_ )   The blocking factor used to distribute
                                      the rows of the array.
       NB_A   (global) DESCA( NB_ )   The blocking factor used to distribute
                                      the columns of the array.
       RSRC_A (global) DESCA( RSRC_ ) The process row over which the first
                                      row  of  the  array  A is distributed.  CSRC_A (global) DESCA( CSRC_ ) The
       process column over which the
                                      first column of the array A is
                                      distributed.
       LLD_A  (local)  DESCA( LLD_ )  The leading dimension of the local
                                      array.  LLD_A >= MAX(1,LOCr(M_A)).

       Let K be the number of rows or columns of a distributed matrix, and assume  that  its  process  grid  has
       dimension p x q.
       LOCr( K ) denotes the number of elements of K that a process would receive if K were distributed over the
       p processes of its process column.
       Similarly, LOCc( K ) denotes the number of elements  of  K  that  a  process  would  receive  if  K  were
       distributed over the q processes of its process row.
       The values of LOCr() and LOCc() may be determined via a call to the ScaLAPACK tool function, NUMROC:
               LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ),
               LOCc(  N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ).  An upper bound for these quantities may be
       computed by:
               LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A
               LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A

ARGUMENTS

       M       (global input) INTEGER
               M is the order of the square submatrix that is copied.  M >= 0.  Unchanged on exit

       I       (global input) INTEGER
               A(I,I) is the global location that the copying starts from.  Unchanged on exit.

       A       (global input/output) REAL array, dimension
               (DESCA(LLD_),*) On entry, the parallel matrix to be copied into or from.  On exit, if REV=1,  the
               copied data.  Unchanged on exit if REV=0.

       DESCA   (global and local input) INTEGER array of dimension DLEN_.
               The array descriptor for the distributed matrix A.

       B       (local input/output) REAL array of size (LDB,M)
               If  REV=0,  this  is  the  global portion of the array A(I:I+M-1,I:I+M-1).  If REV=1, this is the
               unchanged on exit.

       LDB     (local input) INTEGER
               The leading dimension of B.

       II      (global input) INTEGER
               By using REV 0 & 1, data can be sent out and returned again.  If REV=0, then  II  is  destination
               row index for the node(s) receiving the replicated B.  If II>=0,JJ>=0, then node (II,JJ) receives
               the data If II=-1,JJ>=0, then all rows in column JJ receive the data  If  II>=0,JJ=-1,  then  all
               cols  in  row II receive the data If II=-1,JJ=-1, then all nodes receive the data If REV<>0, then
               II is the source row index for the node(s) sending the replicated B.

       JJ      (global input) INTEGER
               Similar description as II above

       REV     (global input) INTEGER
               Use REV = 0 to send global A into locally replicated B (on node (II,JJ)).  Use REV <> 0  to  send
               locally  replicated  B from node (II,JJ) to its owner (which changes depending on its location in
               A) into the global A.

               Implemented by:  G. Henry, May 1, 1997