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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)
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