[97] | 1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
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| 2 | .\" Copyright (c) 1996 Thinking Machines Corporation |
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| 3 | .TH MPI_Comm_create 3 "Dec 08, 2009" "1.4" "Open MPI" |
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| 4 | .SH NAME |
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| 5 | \fBMPI_Comm_create\fP \- Creates a new communicator. |
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| 6 | |
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| 7 | .SH SYNTAX |
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| 8 | .ft R |
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| 9 | .SH C Syntax |
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| 10 | .nf |
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| 11 | #include <mpi.h> |
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| 12 | int MPI_Comm_create(MPI_Comm \fIcomm\fP, MPI_Group\fI group\fP, MPI_Comm\fI *newcomm\fP) |
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| 13 | |
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| 14 | .SH Fortran Syntax |
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| 15 | .nf |
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| 16 | INCLUDE 'mpif.h' |
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| 17 | MPI_COMM_CREATE(\fICOMM, GROUP, NEWCOMM, IERROR\fP) |
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| 18 | INTEGER \fICOMM, GROUP, NEW, IERROR\fP |
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| 19 | |
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| 20 | .SH C++ Syntax |
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| 21 | .nf |
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| 22 | #include <mpi.h> |
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| 23 | MPI::Intercomm MPI::Intercomm::Create(const Group& \fIgroup\fP) const |
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| 24 | |
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| 25 | MPI::Intracomm MPI::Intracomm::Create(const Group& \fIgroup\fP) const |
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| 26 | |
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| 27 | .SH INPUT PARAMETER |
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| 28 | .ft R |
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| 29 | .TP 1i |
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| 30 | comm |
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| 31 | Communicator (handle). |
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| 32 | .TP 1i |
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| 33 | group |
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| 34 | Group, which is a subset of the group of comm (handle). |
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| 35 | |
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| 36 | .SH OUTPUT PARAMETERS |
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| 37 | .ft R |
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| 38 | .TP 1i |
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| 39 | newcomm |
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| 40 | New communicator (handle). |
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| 41 | .ft R |
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| 42 | .TP 1i |
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| 43 | IERROR |
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| 44 | Fortran only: Error status (integer). |
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| 45 | |
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| 46 | .SH DESCRIPTION |
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| 47 | .ft R |
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| 48 | This function creates a new communicator newcomm with communication group |
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| 49 | defined by group and a new context. The function sets \fInewcomm\fR to a new communicator that spans all the processes that are in the group. It sets \fInewcomm\fR to MPI_COMM_NULL for processes that are not in the group. The call is erroneous if not all group arguments have the same value, or if group is not a subset of the group associated with comm. Note that the call must be executed by all processes in comm, even if they do not belong to the new group. |
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| 50 | .sp |
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| 51 | .LP |
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| 52 | |
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| 53 | .SH NOTES |
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| 54 | MPI_Comm_create 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, can be used in subsequent calls to MPI_Comm_create (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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| 55 | |
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| 56 | .SH ERRORS |
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| 57 | Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions 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. |
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| 58 | .sp |
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| 59 | Before the error value is returned, the current MPI error handler is |
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| 60 | 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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| 61 | |
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| 62 | .SH SEE ALSO |
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| 63 | .ft R |
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| 64 | .sp |
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| 65 | MPI_Comm_split |
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| 66 | .sp |
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| 67 | MPI_Intercomm_create |
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| 68 | |
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