MPI_Graph_neighbors_count(3) 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

INCLUDE 'mpif.h'
MPI_GRAPH_NEIGHBORS_COUNT(COMM, RANK, NNEIGHBORS, IERROR)
        INTEGER COMM, RANK, NNEIGHBORS, 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.

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