81 строка
3.2 KiB
Plaintext
81 строка
3.2 KiB
Plaintext
.\" Copyright 2013 Los Alamos National Security, LLC. All rights reserved.
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.\" Copyright 2010 Cisco Systems, Inc. All rights reserved.
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.\" Copyright 2006-2008 Sun Microsystems, Inc.
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.\" Copyright (c) 1996 Thinking Machines Corporation
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.TH MPI_Comm_create_group 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
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.SH NAME
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\fBMPI_Comm_create_group\fP \- Creates a new communicator.
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.SH SYNTAX
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.ft R
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.SH C Syntax
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.nf
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#include <mpi.h>
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int MPI_Comm_create_group(MPI_Comm \fIcomm\fP, MPI_Group\fI group\fP, int\fI tag\fP, MPI_Comm\fI *newcomm\fP)
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.fi
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.SH Fortran Syntax
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.nf
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INCLUDE 'mpif.h'
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MPI_COMM_CREATE_GROUP(\fICOMM, GROUP, TAG, NEWCOMM, IERROR\fP)
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INTEGER \fICOMM, GROUP, TAG, NEWCOMM, IERROR\fP
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.fi
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.SH INPUT PARAMETERS
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.ft R
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.TP 1i
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comm
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Communicator (handle).
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.TP 1i
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group
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Group, which is a subset of the group of comm (handle).
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.TP 1i
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tag
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Tag (integer).
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.SH OUTPUT PARAMETERS
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.ft R
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.TP 1i
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newcomm
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New communicator (handle).
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.ft R
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.TP 1i
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IERROR
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Fortran only: Error status (integer).
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.SH DESCRIPTION
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.ft R
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MPI_Comm_create_group is similar to MPI_Comm_create; however,
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MPI_Comm_create must be called by all processes in the group of
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comm, whereas MPI_Comm_create_group must be called by all processes in group,
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which is a subgroup of the group of \fIcomm\fP. In addition, MPI_Comm_create_group
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requires that \fIcomm\fP is an intracommunicator. MPI_Comm_create_group returns a new
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intracommunicator, \fInewcomm\fP, for which the group argument defines the communication
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group. No cached information propagates from \fIcomm\fP to \fInewcomm\fP.
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Each process must provide a group argument that is a subgroup of the group associated with \fIcomm\fP;
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this could be MPI_GROUP_EMPTY. If a non-empty group is specified, then all processes in that
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group must call the function, and each of these processes must provide the same arguments,
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including a group that contains the same members with the same ordering. Otherwise
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the call is erroneous. If the calling process is a member of the group given as the \fIgroup\fP
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argument, then newcomm is a communicator with group as its associated group. If the
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calling process is not a member of group, e.g., \fIgroup\fP is MPI_GROUP_EMPTY, then the call
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is a local operation and MPI_COMM_NULL is returned as \fInewcomm\fP.
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.sp
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.LP
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.SH NOTES
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MPI_Comm_create_group provides a means of making a subset of processes for the purpose of separate MIMD computation, with separate communication space. \fInewcomm\fR, which is created by MPI_Comm_create_group, can be used in subsequent calls to MPI_Comm_create_group (or other communicator constructors) to further subdivide a computation into parallel sub-computations. A more general service is provided by MPI_Comm_split.
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.SH ERRORS
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Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.
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.sp
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Before the error value is returned, the current MPI error handler is
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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.
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.SH SEE ALSO
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.ft R
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MPI_Comm_create
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