1MPI_Comm_split(3) LAM/MPI MPI_Comm_split(3)
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6 MPI_Comm_split - Creates new communicators based on colors and keys
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9 #include <mpi.h>
10 int MPI_Comm_split(MPI_Comm comm, int colour, int key,
11 MPI_Comm *newcomm)
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14 comm - communicator (handle)
15 colour - control of subset assignment (nonnegative integer)
16 key - control of rank assigment (integer)
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20 newcomm
21 - new communicator (handle)
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25 The colour must be non-negative or MPI_UNDEFINED . This is a collec‐
26 tive call over all ranks in comm .
27 When a communicator is no longer being used, it should be freed with
30 MPI_Comm_free .
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35 All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
36 an additional argument ierr at the end of the argument list. ierr is
37 an integer and has the same meaning as the return value of the routine
38 in C. In Fortran, MPI routines are subroutines, and are invoked with
39 the call statement.
40 All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
42 Fortran.
43
46 If an error occurs in an MPI function, the current MPI error handler is
47 called to handle it. By default, this error handler aborts the MPI
48 job. The error handler may be changed with MPI_Errhandler_set ; the
49 predefined error handler MPI_ERRORS_RETURN may be used to cause error
50 values to be returned (in C and Fortran; this error handler is less
51 useful in with the C++ MPI bindings. The predefined error handler
52 MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
53 needs to be recovered). Note that MPI does not guarantee that an MPI
54 program can continue past an error.
55 All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
57 value; C routines as the value of the function and Fortran routines in
58 the last argument. The C++ bindings for MPI do not return error val‐
59 ues; instead, error values are communicated by throwing exceptions of
60 type MPI::Exception (but not by default). Exceptions are only thrown
61 if the error value is not MPI::SUCCESS .
62 Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
65 functions will return upon an error, there will be no way to recover
66 what the actual error value was.
67 MPI_SUCCESS
68 - No error; MPI routine completed successfully.
69 MPI_ERR_COMM
70 - Invalid communicator. A common error is to use a null commu‐
71 nicator in a call (not even allowed in MPI_Comm_rank ).
72 MPI_ERR_ARG
73 - Invalid argument. Some argument is invalid and is not identi‐
74 fied by a specific error class. This is typically a NULL
75 pointer or other such error.
76 MPI_ERR_INTERN
77 - An internal error has been detected. This is fatal. Please
78 send a bug report to the LAM mailing list (see http://www.lam-
79 mpi.org/contact.php ).
80 MPI_ERR_OTHER
81 - This error is returned when some part of the LAM/MPI implemen‐
82 tation is unable to acquire memory.
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86 MPI_Comm_free
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90 For more information, please see the official MPI Forum web site, which
91 contains the text of both the MPI-1 and MPI-2 standards. These docu‐
92 ments contain detailed information about each MPI function (most of
93 which is not duplicated in these man pages).
94 http://www.mpi-forum.org/
96
100 The LAM Team would like the thank the MPICH Team for the handy program
101 to generate man pages ("doctext" from ftp://ftp.mcs.anl.gov/pub/sow‐
102 ing/sowing.tar.gz ), the initial formatting, and some initial text for
103 most of the MPI-1 man pages.
104
106 csplit.c
107LAM/MPI 7.1.2 2/23/2006 MPI_Comm_split(3)