MPI_Graph_neighbors(3)

NAME
MPI_Graph_neighbors - Returns the neighbors of a node associated with a graph topology

SYNOPSIS
#include "mpi.h"
int MPI_Graph_neighbors ( MPI_Comm comm, int rank, int maxneighbors,
                        int *neighbors )

INPUT PARAMETERS
comm
    - communicator with graph topology (handle)
rank
    - rank of process in group of comm (integer)
maxneighbors
    - size of array neighbors (integer)

OUTPUT PARAMETERS
neighbors
    - ranks of processes that are neighbors to specified process (array of integer)

NOTES FOR FORTRAN
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the end of the argument list. ierr is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement. All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS
All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set ; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error.
MPI_SUCCESS
    - No error; MPI routine completed successfully.
MPI_ERR_TOPOLOGY
    - Invalid topology. Either there is no topology associated with this communicator, or it is not the correct type (e.g., MPI_CART when expecting MPI_GRAPH ).
MPI_ERR_COMM
    - Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank ).
MPI_ERR_ARG
    - Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK ).
MPI_ERR_RANK
    - Invalid source or destination rank. Ranks must be between zero and the size of the communicator minus one; ranks in a receive ( MPI_Recv , MPI_Irecv , MPI_Sendrecv , etc.) may also be MPI_ANY_SOURCE .

LOCATION
graph_nbr.c