NAME¶

MPI_Graph_neighbors_count - Returns the number of neighbors of a node associated with a graph topology.

SYNTAX¶

C Syntax¶

#include <mpi.h>
int MPI_Graph_neighbors_count(MPI_Comm comm, int rank,
	int *nneighbors)

Fortran Syntax¶

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_GRAPH_NEIGHBORS_COUNT(COMM, RANK, NNEIGHBORS, IERROR)
	INTEGER	COMM, RANK, NNEIGHBORS, IERROR

Fortran 2008 Syntax¶

USE mpi_f08
MPI_Graph_neighbors_count(comm, rank, nneighbors, ierror)
	TYPE(MPI_Comm), INTENT(IN) :: comm
	INTEGER, INTENT(IN) :: rank
	INTEGER, INTENT(OUT) :: nneighbors
	INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax¶

#include <mpi.h>
int Graphcomm::Get_neighbors_count(int rank) const

INPUT PARAMETERS¶

comm

Communicator with graph topology (handle).

rank

Rank of process in group of comm (integer).

OUTPUT PARAMETERS¶

nneighbors

Number of neighbors of specified process (integer).

IERROR

Fortran only: Error status (integer).

DESCRIPTION¶

MPI_Graph_neighbors_count and MPI_Graph_neighbors provide adjacency information for a general, graph topology. MPI_Graph_neighbors_count returns the number of neighbors for the process signified by rank.

ERRORS¶

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.

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.

SEE ALSO¶

MPI_Graph_neighbors