NAME

MPI_Dist_graph_neighbors - Returns the neighbors of the calling process in a distributed graph topology.

SYNTAX

C Syntax

#include <mpi.h>
int MPI_Dist_graph_neighbors(MPI_Comm comm, int maxindegree, int sources[], int sourceweights[],


                             int maxoutdegree, int destinations[], int destweights[])

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_DIST_GRAPH_NEIGHBORS(COMM, MAXINDEGREE, SOURCES, SOURCEWEIGHTS,


        MAXOUTDEGREE, DESTINATIONS, DESTWEIGHTS, IERROR)


        INTEGER COMM, MAXINDEGREE, SOURCES(*), SOURCEWEIGHTS(*), MAXOUTDEGREE,


                DESTINATIONS(*), DESTWEIGHTS(*), IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Dist_Graph_neighbors(comm, maxindegree, sources, sourceweights,
		maxoutdegree, destinations, destweights, ierror)
	TYPE(MPI_Comm), INTENT(IN) :: comm
	INTEGER, INTENT(IN) :: maxindegree, maxoutdegree
	INTEGER, INTENT(OUT) :: sources(maxindegree), destinations(maxoutdegree)
	INTEGER :: sourceweights(*), destweights(*)
	INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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).
IERROR: Fortran only: Error status (integer).

DESCRIPTION

MPI_Dist_graph_neighbors returns the source and destination ranks in a distributed graph topology for the calling process. This call will return up to maxindegree source ranks in the sources array and up to maxoutdegree destination ranks in the destinations array. If weights were specified at the time of the communicator's creation then the associated weights are returned in the sourceweights and destweights arrays. If the communicator was created with MPI_Dist_graph_create_adjacent then the order of the values in sources and destinations is identical to the input that was used by the process with the same rank in comm_old in the creation call.

ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is 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.