The functions in this section provide information about the structure of the graph topology. All calls are local.
MPI_Graph_neighbors_count(MPI_Comm comm, int rank, int *nneighbors)
MPI_GRAPH_NEIGHBORS_COUNT(COMM, RANK, NNEIGHBORS, IERROR)INTEGER COMM, RANK, NNEIGHBORS, IERROR
MPI_GRAPH_NEIGHBORS_COUNT returns the number of neighbors for the process signified by rank. It can be used by MPI_GRAPH_NEIGHBORS to give an array of correct size for neighbors. Using Example with rank = 3 would give nneighbors = 2.
MPI_Graph_neighbors(MPI_Comm comm, int rank, int maxneighbors, int *neighbors)
MPI_GRAPH_NEIGHBORS(COMM, RANK, MAXNEIGHBORS, NEIGHBORS, IERROR)INTEGER COMM, RANK, MAXNEIGHBORS, NEIGHBORS(*), IERROR
MPI_GRAPH_NEIGHBORS returns the part of the edges array associated with process rank. Using Example , rank = 3 would return neighbors = 0, 2. Another use is given in Example .