Makes a new communicator to which topology information has been attached
int MPI_Graph_create ( comm_old, nnodes, index, edges, reorder, comm_graph )
- comm_old - input communicator without topology (handle)
- nnodes - number of nodes in graph (integer)
- index - array of integers describing node degrees (see below)
- edges - array of integers describing graph edges (see below)
- reorder - ranking may be reordered (true) or not (false) (logical)
- comm_graph - communicator with graph topology added (handle)
We ignore the reorder info currently.
Notes for Fortran
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have
an additional argument ierr at the end of the argument list. ierr
is an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with the
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER
All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value;
C routines as the value of the function and Fortran routines in the last
argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with MPI_Errhandler_set; the predefined error handler
MPI_ERRORS_RETURN may be used to cause error values to be returned.
Note that MPI does not guarentee that an MPI program can continue past
- MPI_SUCCESS - No error; MPI routine completed successfully.
- MPI_ERR_TOPOLOGY - Invalid topology. Either there is no topology
associated with this communicator, or it is not the correct type (e.g.,
MPI_CART when expecting MPI_GRAPH).
- MPI_ERR_COMM - Invalid communicator. A common error is to use a null
communicator in a call (not even allowed in MPI_Comm_rank).
- MPI_ERR_ARG - Invalid argument. Some argument is invalid and is not
identified by a specific error class (e.g., MPI_ERR_RANK).