NAME

MPI_Graph_get - Retrieves graph topology information associated with a communicator.

SYNTAX

C Syntax

#include <mpi.h>
int MPI_Graph_get(MPI_Comm comm, int maxindex, int maxedges,
	int index[], int edges[])

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_GRAPH_GET(COMM, MAXINDEX, MAXEDGES, INDEX, EDGES, IERROR)
	INTEGER	COMM, MAXINDEX, MAXEDGES, INDEX(*)
	INTEGER	EDGES(*), IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Graph_get(comm, maxindex, maxedges, index, edges, ierror)
	TYPE(MPI_Comm), INTENT(IN) :: comm
	INTEGER, INTENT(IN) :: maxindex, maxedges
	INTEGER, INTENT(OUT) :: index(maxindex), edges(maxedges)
	INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

#include <mpi.h>
void Graphcomm::Get_topo(int maxindex, int maxedges,
	int index[], int edges[]) const

INPUT PARAMETERS

comm: Communicator with graph structure (handle).
maxindex: Length of vector index in the calling program (integer).
maxedges: Length of vector edges in the calling program (integer).

OUTPUT PARAMETERS

index: Array of integers containing the graph structure (for details see the definition of MPI_Graph_create).
edges: Array of integers containing the graph structure.
IERROR: Fortran only: Error status (integer).

DESCRIPTION

Functions MPI_Graphdims_get and MPI_Graph_get retrieve the graph-topology information that was associated with a communicator by MPI_Graph_create.

The information provided by MPI_Graphdims_get can be used to dimension the vectors index and edges correctly for a call to MPI_Graph_get.

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.