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PCLACP3(l)			       )			    PCLACP3(l)

NAME
       PCLACP3 - i an auxiliary	routine	that copies from a global parallel ar-
       ray into	a local	replicated array or vise versa

SYNOPSIS
       SUBROUTINE PCLACP3( M, I, A, DESCA, B, LDB, II, JJ, REV )

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

	   INTEGER	   DESCA( * )

	   COMPLEX	   A( *	), B( LDB, * )

PURPOSE
       PCLACP3 is an auxiliary routine that copies from	a global parallel  ar-
       ray  into a local replicated array or vise versa. Notice	that   the en-
       tire 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  vec-
       tor.  This vector stores	the information	required to establish the map-
       ping 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 as-
       sume that its process grid has dimension	p x q.
       LOCr(  K	) denotes the number of	elements of K that a process would re-
       ceive 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) COMPLEX 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) COMPLEX 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)  re-
	       ceiving	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 re-
	       ceive 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.

FURTHER	DETAILS
       Implemented by:	M. Fahey, May 28, 1999

ScaLAPACK version 1.7		13 August 2001			    PCLACP3(l)

NAME | SYNOPSIS | PURPOSE | ARGUMENTS | FURTHER DETAILS

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