MPI_TYPE_EXTENT, MPI_Type_extent

Purpose

Returns the extent of any defined datatype.

C synopsis

#include <mpi.h>
int MPI_Type_extent(MPI_Datatype datatype,MPI_Aint *size);

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_TYPE_EXTENT(INTEGER DATATYPE,INTEGER EXTENT,INTEGER IERROR)

Parameters

datatype
     is the datatype (handle) (IN)

size
     is the datatype extent (integer) (OUT)

IERROR
     is the FORTRAN return code. It is always the last argument.

Description

This subroutine returns the extent of a datatype. The default extent of a
datatype is the span from the first byte to the last byte occupied by
entries in this datatype and rounded up to satisfy alignment requirements.

Notes

MPI_TYPE_GET_EXTENT supersedes MPI_TYPE_EXTENT.

Rounding for alignment is not done when MPI_UB is used to define the
datatype. Types defined with MPI_LB, MP_UB, or with any type that itself
contains MPI_LB or MPI_UB may return an extent that is not directly related
to the layout of data in memory. Refer to MPI_TYPE_STRUCT or
MPI_TYPE_CREATE_STRUCT for more information on MPI_LB and MPI_UB.

MPI_TYPE_CREATE_RESIZED can also alter default extent.

You can still use this subroutine in FORTRAN 64-bit applications if you
know that all datatype extents can be represented by an INTEGER, but you do
so at your own risk. MPI_TYPE_GET_EXTENT should be used in new codes.

Errors

Invalid datatype

MPI not initialized

MPI already finalized

Related information