PSLARED2D(l)						   LAPACK routine (version 1.5) 					      PSLARED2D(l)

NAME

       PSLARED2D  -  redistribute a 1D array  It assumes that the input array, BYROW, is distributed across columns and that all process rows con-
       tain the same copy of BYROW

SYNOPSIS

       SUBROUTINE PSLARED2D( N, IA, JA, DESC, BYROW, BYALL, WORK, LWORK )

	   INTEGER	     IA, JA, LWORK, N

	   INTEGER	     DESC( * )

	   REAL 	     BYALL( * ), BYROW( * ), WORK( LWORK )

PURPOSE

       PSLARED2D redistributes a 1D array and will contain the entire array.

       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

       NP = Number of local rows in BYROW()

       N       (global input) INTEGER
	       The number of elements to be redistributed.  N >= 0.

       IA      (global input) INTEGER
	       IA must be equal to 1

       JA      (global input) INTEGER
	       JA must be equal to 1

       DESC    (global/local input) INTEGER Array of dimension DLEN_
	       A 2D array descriptor, which describes BYROW

       BYROW   (local input) distributed block cyclic REAL	      array
	       global dimension (N), local dimension NP BYCOL is distributed across the process columns All process rows are  assumed  to  contain
	       the same value

       BYALL   (global output) REAL	       global dimension( N )
	       local  dimension (N) BYALL is exactly duplicated on all processes It contains the same values as BYCOL, but it is replicated across
	       all processes rather than being distributed

	       BYALL(i) = BYCOL( NUMROC(i,NB,MYROW,0,NPROW ) on the procs whose MYROW == mod((i-1)/NB,NPROW)

       WORK    (local workspace) REAL		 dimension (LWORK)
	       Used to hold the buffers sent from one process to another

       LWORK   (local input) INTEGER size of WORK array LWORK >=
	       LWORK >= NUMROC(N, DESC( NB_ ), 0, 0, NPCOL)

LAPACK version 1.5						    12 May 1997 						      PSLARED2D(l)