MPI_Pack_size

Returns the upper bound on the amount of space needed to pack a message

Synopsis

#include "mpi.h"
int MPI_Pack_size ( int incount, MPI_Datatype datatype, MPI_Comm comm, 
                   int *size )

Input Parameters

	incount	count argument to packing call (integer)
	datatype	datatype argument to packing call (handle)
	comm	communicator argument to packing call (handle)

Output Parameter

size

upper bound on size of packed message, in bytes (integer)

Notes

The MPI standard document describes this in terms of MPI_Pack, but it applies to both MPI_Pack and MPI_Unpack. That is, the value size is the maximum that is needed by either MPI_Pack or MPI_Unpack.

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_Errhandler_set; 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.

MPI_SUCCESS

No error; MPI routine completed successfully.

MPI_ERR_COMM

Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).

MPI_ERR_TYPE

Invalid datatype argument. May be an uncommitted MPI_Datatype (see MPI_Type_commit).

MPI_ERR_ARG

Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK).

Location:pack_size.c