1MPI_Graph_neighbors_count(3) LAM/MPI MPI_Graph_neighbors_count(3)
2
6 MPI_Graph_neighbors_count - Returns the number of neighbors of a node
7 associated with a graph topology
8
10 #include <mpi.h>
11 int MPI_Graph_neighbors_count(MPI_Comm comm, int rank,
12 int *pnbr)
13
15 comm - communicator with graph topology (handle)
16 rank - rank of process in group of comm (integer)
17
20 pnbr - number of neighbors of specified process (integer)
21
24 All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
25 an additional argument ierr at the end of the argument list. ierr is
26 an integer and has the same meaning as the return value of the routine
27 in C. In Fortran, MPI routines are subroutines, and are invoked with
28 the call statement.
29 All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
31 Fortran.
32
35 If an error occurs in an MPI function, the current MPI error handler is
36 called to handle it. By default, this error handler aborts the MPI
37 job. The error handler may be changed with MPI_Errhandler_set ; the
38 predefined error handler MPI_ERRORS_RETURN may be used to cause error
39 values to be returned (in C and Fortran; this error handler is less
40 useful in with the C++ MPI bindings. The predefined error handler
41 MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
42 needs to be recovered). Note that MPI does not guarantee that an MPI
43 program can continue past an error.
44 All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
46 value; C routines as the value of the function and Fortran routines in
47 the last argument. The C++ bindings for MPI do not return error val‐
48 ues; instead, error values are communicated by throwing exceptions of
49 type MPI::Exception (but not by default). Exceptions are only thrown
50 if the error value is not MPI::SUCCESS .
51 Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
54 functions will return upon an error, there will be no way to recover
55 what the actual error value was.
56 MPI_SUCCESS
57 - No error; MPI routine completed successfully.
58 MPI_ERR_TOPOLOGY
59 - Invalid topology. Either there is no topology associated with
60 this communicator, or it is not the correct type (e.g., MPI_CART
61 when expecting MPI_GRAPH ).
62 MPI_ERR_COMM
63 - Invalid communicator. A common error is to use a null commu‐
64 nicator in a call (not even allowed in MPI_Comm_rank ).
65 MPI_ERR_ARG
66 - Invalid argument. Some argument is invalid and is not identi‐
67 fied by a specific error class. This is typically a NULL
68 pointer or other such error.
69 MPI_ERR_RANK
70 - Invalid source or destination rank. Ranks must be between
71 zero and the size of the communicator minus one; ranks in a
72 receive ( MPI_Recv , MPI_Irecv , MPI_Sendrecv , etc.) may also
73 be MPI_ANY_SOURCE .
74
78 For more information, please see the official MPI Forum web site, which
79 contains the text of both the MPI-1 and MPI-2 standards. These docu‐
80 ments contain detailed information about each MPI function (most of
81 which is not duplicated in these man pages).
82 http://www.mpi-forum.org/
84
88 The LAM Team would like the thank the MPICH Team for the handy program
89 to generate man pages ("doctext" from ftp://ftp.mcs.anl.gov/pub/sow‐
90 ing/sowing.tar.gz ), the initial formatting, and some initial text for
91 most of the MPI-1 man pages.
92
94 graphnbrcount.c
95LAM/MPI 7.1.2 2/23/2006 MPI_Graph_neighbors_count(3)