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HPL_reduce(3)		     HPL Library Functions		 HPL_reduce(3)

NAME
       HPL_reduce - Reduce operation.

SYNOPSIS
       #include	"hpl.h"

       int HPL_reduce( void * BUFFER, const int	COUNT, const HPL_T_TYPE	DTYPE,
       const HPL_T_OP OP, const	int ROOT, MPI_Comm COMM	);

DESCRIPTION
       HPL_reduce performs a global reduce operation across all	processes of a
       group.	Note  that  the	 input buffer is  used as workarray and	in all
       processes but the accumulating process corrupting the original data.

ARGUMENTS
       BUFFER  (local input/output)    void *
	       On entry,  BUFFER  points to  the  buffer to be	 reduced.   On
	       exit,   and   in	process	of rank	 ROOT  this array contains the
	       reduced data.  This  buffer  is also used as  workspace	during
	       the operation in	the other processes of the group.

       COUNT   (global input)	       const int
	       On  entry,   COUNT  indicates the number	of entries in  BUFFER.
	       COUNT must be at	least zero.

       DTYPE   (global input)	       const HPL_T_TYPE
	       On entry,  DTYPE	 specifies the type of the buffers operands.

       OP      (global input)	       const HPL_T_OP
	       On entry, OP is a pointer to the	local combine function.

       ROOT    (global input)	       const int
	       On entry, ROOT is the coordinate	of the accumulating process.

       COMM    (global/local input)    MPI_Comm
	       The MPI communicator identifying	the process collection.

SEE ALSO
       HPL_broadcast (3),  HPL_all_reduce (3),	HPL_barrier (3),  HPL_min (3),
       HPL_max (3), HPL_sum (3).

HPL 2.1			       October 26, 2012			 HPL_reduce(3)

NAME | SYNOPSIS | DESCRIPTION | ARGUMENTS | SEE ALSO

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