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MPI_Pack_size(3) man page (version 1.3.4)

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NAME

       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

       INCLUDE 'mpif.h'
       MPI_PACK_SIZE(INCOUNT, DATATYPE, COMM, SIZE, IERROR)
            INTEGER   INCOUNT, DATATYPE, COMM, SIZE, IERROR

C++ Syntax

       #include <mpi.h>
       int Datatype::Pack_size(int incount, const Comm& comm) const

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

       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  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

       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
       MPI_Pack
       MPI_Unpack

1.3.4                            Nov 11, 2009                 MPI_Pack_size(3)

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