NAME

MPI_Graph_neighbors - Returns the ranks of the nodes connected to a given node in a graph communicator

SYNOPSIS

#include <mpi.h> 
int MPI_Graph_neighbors(MPI_Comm comm , int rank , int maxneighbors , int *neighbors ); 
#include <pmpi.h> 
int PMPI_Graph_neighbors(MPI_Comm comm , int rank , int maxneighbors , int *neighbors ); 

INPUT PARAMETERS

comm - graph communicator (handle)

rank - rank of the node to obtain edges of (integer)

maxneighbors - size of the neighbors array (integer)

OUTPUT PARAMETER

neighbors - ranks of the connected edges (array).

DESCRIPTION

The MPI_Graph_neighbors() function is used to obtain the edges connected to the node at rank , within the graph communicator comm . This is returned via the neighbors array of size maxneighbors . This size can be determined by using the MPI_Graph_neighbors_count() function.

The communicator must be a valid one (not MPI_COMM_NULL). PMPI_Graph_neighbors() is the profiling version of this function.

ERRORS

All MPI routines except for MPI_Wtime and MPI_Wtick return an error value. The the current MPI error handler is invoked if this return value is not MPI_SUCCESS. The default error handler aborts, but this may be changed with by using the MPI_Errhandler_set() function. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned instead. Note that MPI does not guarentee that an MPI program can continue past an error. In this implementation, all errors except MPI_ERR_INTERN or MPI_ERR_OTHER should always be recoverable.

MPI_SUCCESS - No error;

MPI_ERR_COMM - Invalid communicator;

MPI_ERR_TOPOLOGY - Not a graph communicator;

MPI_ERR_RANK - Invalid rank;

MPI_ERR_DIMS - Invalid output array.

SEE ALSO

MPI_Cart_get (3) MPI_Cartdim_get (3) MPI_Graph_create (3) MPI_Graphdims_get (3) MPI_Graph_get (3) MPI_Graph_neighbors_count (3)

• Lockless
• MPI Documentation
• MPI_Graph_neighbors