PDLACP3(l)						   LAPACK routine (version 1.5) 						PDLACP3(l)

NAME

       PDLACP3 - i an auxiliary routine that copies from a global parallel  array into a local replicated array or vise versa

SYNOPSIS

       SUBROUTINE PDLACP3( M, I, A, DESCA, B, LDB, II, JJ, REV )

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

	   INTEGER	   DESCA( * )

	   DOUBLE	   PRECISION A( * ), B( LDB, * )

PURPOSE

       PDLACP3 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 col-
       umn.
       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) DOUBLE PRECISION 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) DOUBLE PRECISION 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

LAPACK version 1.5						    12 May 1997 							PDLACP3(l)