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_rank 3 "Dec 08, 2009" "1.4" "Open MPI" |
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4 | .SH NAME |
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5 | \fBMPI_Comm_rank\fP \- Determines the rank of the calling process in the 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_rank(MPI_Comm \fIcomm\fP, int\fI *rank\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_RANK(\fICOMM, RANK, IERROR\fP) |
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18 | INTEGER \fICOMM, RANK, 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 | int Comm::Get_rank() const |
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24 | |
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25 | .SH INPUT PARAMETERS |
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26 | .ft R |
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27 | .TP 1i |
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28 | comm |
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29 | Communicator (handle). |
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30 | |
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31 | .SH OUTPUT PARAMETERS |
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32 | .ft R |
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33 | .TP 1i |
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34 | rank |
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35 | Rank of the calling process in group of comm (integer). |
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36 | .ft R |
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37 | .TP 1i |
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38 | IERROR |
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39 | Fortran only: Error status (integer). |
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40 | |
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41 | .SH DESCRIPTION |
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42 | .ft R |
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43 | This function gives the rank of the process in the |
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44 | particular communicator's group. It is equivalent to accessing the |
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45 | communicator's group with MPI_Comm_group, computing the rank using MPI_Group_rank, and then freeing the temporary group via MPI_Group_free. |
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46 | .sp |
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47 | Many programs will be written with the master-slave model, where one process (such as the rank-zero process) will play a supervisory role, and the other processes will serve as compute nodes. In this framework, MPI_Comm_size and MPI_Comm_rank are useful for determining the roles of the various processes of a communicator. |
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48 | |
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49 | .SH ERRORS |
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50 | 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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51 | .sp |
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52 | Before the error value is returned, the current MPI error handler is |
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53 | 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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54 | |
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55 | .SH SEE ALSO |
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56 | .ft R |
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57 | .sp |
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58 | .nf |
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59 | MPI_Comm_group |
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60 | MPI_Comm_size |
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61 | MPI_Comm_compare |
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62 | |
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