MPI_Graph_get(3)

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.

SEE ALSO

MPI_Graph_create
MPI_Graphdims_get