MPI Subroutine Reference

A_SAMPLE_MPI_SUBROUTINE, A_Sample_MPI_subroutine

Purpose

Provides a brief description of the subroutine or function.

C synopsis

Header file mpi.h supplies ANSI-C prototypes for every subroutine and function described in MPI subroutines and functions.

#include <mpi.h>
int A_Sample_MPI_subroutine (one or more parameters);

In the C prototype, a declaration of void * indicates that a pointer to any datatype is allowable.

C++ synopsis

#include mpi.h
type MPI::A_Sample_MPI_subroutine(one or more parameters);

In the C++ prototype, a declaration of void* indicates that a pointer to any datatype is allowable.

For information about predefined constants for C++, see IBM Parallel Environment for AIX: MPI Programming Guide.

FORTRAN synopsis

include 'mpif.h' or use mpi
A_SAMPLE_MPI_SUBROUTINE (ONE OR MORE PARAMETERS);

In the FORTRAN subroutines, formal parameters are described using a subroutine prototype format, even though FORTRAN does not support prototyping. The term CHOICE indicates that any FORTRAN datatype is valid.

Parameters

Argument or parameter definitions are listed as follows:

parameter_1

description of parameter_1 (type)

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·
·

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parameter_n

description of parameter_n (type)

IERROR

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

Parameter types:

IN

A call uses this parameter, but does not update an argument.

INOUT

A call uses this parameter and updates an argument.

OUT

A call returns information by way of an argument, but does not use its input value.

Description

This section contains a detailed description of the subroutine or function.

Notes

If applicable, this section contains notes about PE MPI, as it relates to the requirements of the MPI standard. PE MPI intends to comply fully with the requirements of the MPI standard. There are some issues, however, that the MPI standard leaves open to the implementation's choice.

Errors

For non-file-handle errors, a single list appears here.

For errors on a file handle, up to three lists appear:

• Fatal errors:

  Non-recoverable errors are listed here.

• Returning errors (MPI error class):

  Errors that by default return an error code to the caller appear here. These are normally recoverable errors and the error class is specified so you can identify the cause of failure.

• Errors returned by completion routine (MPI error class):

  Errors that by default return an error code to the caller at one of the WAIT or TEST calls appear here. These are normally recoverable errors and the error class is specified so you can identify the cause of failure.

In almost every subroutine, the C version is invoked as a function returning an integer. In the FORTRAN version, the routine is called as a subroutine; that is, it has no return value.

For more information about errors, see IBM Parallel Environment for AIX: Messages, which provides a listing of all the error messages issued as well as the error class to which the message belongs.

Related information

This section contains a list of the related subroutines or functions in this book.

For C and FORTRAN, MPI uses the same spelling for subroutine names. The only distinction is the capitalization. For the purpose of clarity, when referring to a subroutine without specifying whether it is the FORTRAN version or the C version, all uppercase letters are used.

FORTRAN refers to FORTRAN 77 (F77) bindings, which are officially supported for MPI. However, F77 bindings for MPI can be used by FORTRAN 90. FORTRAN 90 and High Performance FORTRAN (HPF) offer array section and assumed shape arrays as parameters on calls. These are not safe with MPI.