DragonFly On-Line Manual Pages

Search: Section:  

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)

Search: Section: