Skip to content

Latest commit

 

History

History
86 lines (57 loc) · 1.89 KB

MPI_Pack_size.3.rst

File metadata and controls

86 lines (57 loc) · 1.89 KB
Raw

MPI_Pack_size

:ref:`MPI_Pack_size` - Returns the upper bound on the amount of space needed to pack a message.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Pack_size(int incount, MPI_Datatype datatype, MPI_Comm comm,
     int *size)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_PACK_SIZE(INCOUNT, DATATYPE, COMM, SIZE, IERROR)
     INTEGER INCOUNT, DATATYPE, COMM, SIZE, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Pack_size(incount, datatype, comm, size, ierror)
     INTEGER, INTENT(IN) :: incount
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     TYPE(MPI_Comm), INTENT(IN) :: comm
     INTEGER, INTENT(OUT) :: size
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • incount: Count argument to packing call (integer).
  • datatype: Datatype argument to packing call (handle).
  • comm: Communicator argument to packing call (handle).

OUTPUT PARAMETERS

  • size: Upper bound on size of packed message, in bytes (integer).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_Pack_size` allows the application to find out how much space is needed to pack a message. A call to MPI_Pack_size(incount, datatype, comm, size) returns in size an upper bound on the increment in position that would occur in a call to :ref:`MPI_Pack`, with the same values for incount, datatype, and comm.

Rationale: The call returns an upper bound, rather than an exact bound, since the exact amount of space needed to pack the message may depend on the context (e.g., first message packed in a packing unit may take more space).

ERRORS

.. seealso::
   * :ref:`MPI_Pack`
   * :ref:`MPI_Unpack`