MPI_TYPE_LB, MPI_Type_lb

Purpose

Returns the lower bound of a datatype.

C synopsis

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

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_TYPE_LB(INTEGER DATATYPE,INTEGER DISPLACEMENT,INTEGER IERROR)

Parameters

datatype
     is the datatype (handle) (IN)

displacement
     is the displacement of lower bound from the origin in bytes (integer)
     (OUT)

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

Description

This subroutine returns the lower bound of a specific datatype.

In general, the lower bound is the offset of the lowest address byte in the
datatype. Datatype constructors with explicit MPI_LB and vector
constructors with negative stride can produce lb < 0. The lower bound
cannot be greater than the upper bound. For a type with MPI_LB in its
ancestry, the value returned by MPI_TYPE_LB may not be related to the
displacement of the lowest address byte. Refer to MPI_TYPE_STRUCT for more
information on MPI_LB and MPI_UB.

Notes

MPI_TYPE_GET_EXTENT supersedes MPI_TYPE_LB.

For FORTRAN 64-bit codes, an INTEGER may not be enough to represent the
lower bound. When the lower bound is known to be representable by an
INTEGER, this subroutine remains usable at your own risk. New codes should
always use MPI_TYPE_GET_EXTENT.

Errors

Invalid datatype

MPI not initialized

MPI already finalized

Related information

     MPI_TYPE_STRUCT