mpi_get_elements(3openmpi) [osx man page]

MPI_Get_elements(3OpenMPI)												MPI_Get_elements(3OpenMPI)

NAME

       MPI_Get_elements  - Returns the number of basic elements in a data type.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Get_elements(MPI_Status *status, MPI_Datatype datatype,
	    int *count)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_GET_ELEMENTS(STATUS, DATATYPE, COUNT, IERROR)
	    INTEGER   STATUS(MPI_STATUS_SIZE), DATATYPE, COUNT, IERROR

C++ Syntax
       #include <mpi.h>
       int Status::Get_elements(const Datatype& datatype) const

INPUT PARAMETERS

       status	 Return status of receive operation (status).

       datatype  Datatype used by receive operation (handle).

OUTPUT PARAMETERS

       count	 Number of received basic elements (integer).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       MPI_Get_elements  behaves  different  from  MPI_Get_count,  which  returns  the number of "top-level entries" received, i.e., the number of
       "copies" of type datatype. MPI_Get_count may return any integer value k, where 0 =< k =< count. If MPI_Get_count returns k, then the number
       of  basic elements received (and the value returned by  MPI_Get_elements) is n * k, where n is the number of basic elements in the type map
       of datatype. If the number of basic elements received is not a multiple of n, that is, if the receive operation has not received  an  inte-
       gral number of datatype "copies," then MPI_Get_count returns the value MPI_UNDEFINED.

       Example: Usage of MPI_Get_count and MPI_Get_element:

	 ...
	 CALL MPI_TYPE_CONTIGUOUS(2, MPI_REAL, Type2, ierr)
	 CALL MPI_TYPE_COMMIT(Type2, ierr)
	 ...
	 CALL MPI_COMM_RANK(comm, rank, ierr)
	 IF(rank.EQ.0) THEN
	       CALL MPI_SEND(a, 2, MPI_REAL, 1, 0, comm, ierr)
	       CALL MPI_SEND(a, 3, MPI_REAL, 1, 0, comm, ierr)
	 ELSE
	       CALL MPI_RECV(a, 2, Type2, 0, 0, comm, stat, ierr)
	       CALL MPI_GET_COUNT(stat, Type2, i, ierr)     ! returns i=1
	       CALL MPI_GET_ELEMENTS(stat, Type2, i, ierr)  ! returns i=2
	       CALL MPI_RECV(a, 2, Type2, 0, 0, comm, stat, ierr)
	       CALL MPI_GET_COUNT(stat, Type2, i, ierr) ! returns i=MPI_UNDEFINED
	       CALL MPI_GET_ELEMENTS(stat, Type2, i, ierr)  ! returns i=3
	 END IF

       The  function MPI_Get_elements can also be used after a probe to find the number of elements in the probed message. Note that the two func-
       tions MPI_Get_count and MPI_Get_elements return the same values when they are used with primitive data types.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func-
       tions  do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except  for
       I/O  function  errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be
       used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO

       MPI_Get_count

Open MPI 1.2							  September 2006					MPI_Get_elements(3OpenMPI)

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MPI_Get_elements(3)							MPI						       MPI_Get_elements(3)

NAME

       MPI_Get_elements -  Returns the number of basic elements in a datatype

SYNOPSIS

       int MPI_Get_elements(MPI_Status *status, MPI_Datatype datatype, int *elements)

INPUT PARAMETERS

       status - return status of receive operation (Status)
       datatype
	      - datatype used by receive operation (handle)

OUTPUT PARAMETER

       count  - number of received basic elements (integer)

NOTES

       If  the size of the datatype is zero and the amount of data returned as determined by status is also zero, this routine will return a count
       of zero.  This is consistent with a clarification made by the MPI Forum.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the end of the argument  list.   ierr
       is  an integer and has the same meaning as the return value of the routine in C.  In Fortran, MPI routines are subroutines, and are invoked
       with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the function and Fortran  routines	in
       the  last  argument.  Before the value is returned, the current MPI error handler is called.  By default, this error handler aborts the MPI
       job.  The error handler may  be	changed  with  MPI_Comm_set_errhandler	(for  communicators),  MPI_File_set_errhandler	(for  files),  and
       MPI_Win_set_errhandler  (for  RMA  windows).   The  MPI-1 routine MPI_Errhandler_set may be used but its use is deprecated.  The predefined
       error handler MPI_ERRORS_RETURN may be used to cause error values to be returned.  Note that MPI does not guarentee that an MPI program can
       continue past an error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
	      - No error; MPI routine completed successfully.

LOCATION

       get_elements.c

								     4/8/2011						       MPI_Get_elements(3)

Linux and UNIX Man Pages

mpi_get_elements(3openmpi) [osx man page]

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