osx man page for mpi_sizeof

MPI_Sizeof(3OpenMPI)													      MPI_Sizeof(3OpenMPI)

NAME
       MPI_Sizeof - Returns the size, in bytes, of the given type

SYNTAX
Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_SIZEOF(X, SIZE, IERROR)
       <type>	 X
       INTEGER	 SIZE, IERROR

INPUT PARAMETER
       X	 A Fortran variable of numeric intrisic type (choice).

OUTPUT PARAMETERS
       SIZE	 Size of machine representation of that type (integer).

       IERROR	 Error status (integer).

DESCRIPTION
       MPI_SIZEOF  returns the size (in bytes) of the machine representation of the given variable. It is a generic Fortran type and has a Fortran
       binding only. This routine is similar to the sizeof builtin in C/C++. However, if given an array argument, it returns the size of the  base
       element, not the size of the whole array.

NOTES
       This function is not available in C/C++ because it is not necessary.

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 the MPI man page for a full list of MPI error codes.

Open MPI 1.2							  September 2006					      MPI_Sizeof(3OpenMPI)