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**NAME**

MPI_Dist_graph_neighbors - Provides adjacency information for a distributed graph topology.

**SYNOPSIS**

int MPI_Dist_graph_neighbors(MPI_Comm comm, int maxindegree, int sources[], int sourceweights[], int maxoutdegree, int destinations[], int destweights[])

**INPUT** **PARAMETERS**

comm- communicator with distributed graph topology (handle)maxindegree- size of sources and sourceweights arrays (non-negative integer)maxoutdegree- size of destinations and destweights arrays (non-negative integer)

**OUTPUT** **PARAMETERS**

sources- processes for which the calling process is a destination (array of non-negative integers)sourceweights- weights of the edges into the calling process (array of non-negative integers)destinations- processes for which the calling process is a source (array of non-negative integers)destweights- weights of the edges out of the calling process (array of non-negative integers)

**THREAD** **AND** **INTERRUPT** **SAFETY**

This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such asmallocor other non-MPICH runtime routines that are themselves not interrupt-safe.

**NOTES** **FOR** **FORTRAN**

All MPI routines in Fortran (except forMPI_WTIMEandMPI_WTICK) have an additional argumentierrat the end of the argument list.ierris 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 thecallstatement. All MPI objects (e.g.,MPI_Datatype,MPI_Comm) are of typeINTEGERin Fortran.

**ERRORS**

All MPI routines (exceptMPI_WtimeandMPI_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 withMPI_Comm_set_errhandler(for communicators),MPI_File_set_errhandler(for files), andMPI_Win_set_errhandler(for RMA windows). The MPI-1 routineMPI_Errhandler_setmay be used but its use is deprecated. The predefined error handlerMPI_ERRORS_RETURNmay be used to cause error values to be returned. Note that MPI doesnotguarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.MPI_SUCCESS- No error; MPI routine completed successfully. 11/9/2015 MPI_Dist_graph_neighbors(3)